Philip Woodward , Gearless Clock, Horology

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Building Dr Woodwards Gearless Clock – (Plans by J. Wilding) by C.Raynerd Introduction: Back in 2003/04 at the age of 20 y/o the professor and my tutor at Uni was hugely into Patek Philippe watches. I had a bit of interest and because Patek make hand made watches they after show images of their production shops and this brought out my hidden engineering interests. Knowing I couldn`t buy a Patek, I purchased some old pocket watches off ebay to take apart (Smiths). It must have been total luck, but I managed to fix one and suddenly thought I was a clock maker. I decided to buy a Unimat 3 lathe off ebay that I somehow won it at a fantastic price. I made a few posts on NAWCC forum and a chap over in Yorkshire invited me around to see his Unimat 3, clock builds and repairs. In his home we discussed the current ME article showing John Wilding who had just finished writing his plans for Dr Woodward’s Gearless Clock and was posting them in Model Engineer mag. Being a fool, I ordered all the materials and purchased a copy of ME (just the first edition of the build). I asked my dad for some help and one Saturday morning we drilled 3 mounting holes for the brass back plate and failed when it came to soft soldering 3 washers on the back!!! I realised very quickly that I didn`t have the skills to make a clock and so all the materials and lathe were sold. So now in 2011, with a couple of years experience behind me, I`m going to give this another go. I recently ordered all the brass plate and received this a couple of weeks ago and I`m just waiting on the remaining materials, mainly imperial bar stock to arrive from College Engineering Supplies. I`ve also taken delivery of a length of nylon cord and some 0.006” spring steel. Last week while on holiday, I appreciatively took delivery of some 1/8” ID bearings from Clive off Madmodder! This is the clock built by John Wilding:

Dr Woodward originally wrote about the design in his book – My Own Right Time but sadly I can`t find it in the library. I have of course purchased John Wildings lovely write up of the plans and build process. He mainly cuts the clock using a Unimat, I`ll be following his methods unless I can utilize my small mill. I should state right away that this build log has be written already by the notorious GadgetBuilder who details fantastically his build of this clock. He has made some excellent modifications of Wiliding’s design, especially the automatic maintaining works. Unfortunately I`m not confident, intelligent or daring enough to deviate from the plans other than a couple of fasteners where I`ll be using metric instead of the specific BA series.I would also

or daring enough to deviate from the plans other than a couple of fasteners where I`ll be using metric instead of the specific BA series.I would also like to thank John, Gadget builder for all the help he has given me through this journey of building my first clock! Without his advice and insight, I would have struggled to complete the clock. The clock uses a really unique method to run. A series of colliding pawls, hooks and rods give the pendulum an impulse, with the energy provided by the large weight. There are two main stages to the clock, the going motion which regulated time and provides an impulse to the pendulum and the daisy motion. I`m going to start back-to-front and talk about the daisy motion first. Basically, the mechanism rotates a main central arbor once each hour – the minute hand is connected to this. The daisy motion is used to convert that single hour rotation into a 1/12 of a turn for the hour hand. Here is a youtube video I made of my daisy wheel plus a link to a much better video by gadget builder: httpv://

As you can probably tell it works off a cam action. This is a really neat and novel idea allowing you to generate the hour movement from the minute movement – remember, without gears! The smart thing is, a taper pin is removed from the centre arbour and the entire daisy motion mechanics can be removed! This is why I mentioned this first, that just leaves us with the rest of the motion works. This clock only receives an impulse to the pendulum once every 60 seconds! This means everything involved with the count wheel must be very low on friction. Look at the pendulum and you will find two brackets. The upper one catches a tooth on the count wheel (the top wheel that looks like an escape wheel, NOT the pin wheel) and the pendulum is of such a length that in 60 seconds the count wheel goes around once. I`m wondering if a minute hand could be attached to the countwheel?? You probably can`t see in the photo, but one tooth on the count wheel is slightly deeper than the rest. When the pawl on the pendulum drops into this tooth, it pulls a lever down at the rear of the wheel. This lever has two section a bit like this “ > “ so as the top lever is pulled down anticlockwise, the bottom lever also moves down. This bottom section pushes down on the bottom “impulse pawl” of the pendulum (the pawl connected to the bottom bracket of the pendulum rod). This actually pulls the count wheel (the pin wheel) anti-clockwise for a second but at this point the weight which is wrapped around the count wheel to pull it clockwise, pulling the wheel back clockwise again. Now however, the levers are not bearing down on the impulse pawl (the count wheel pawl is back in a normal small tooth) and it is free to lift up out of the pin it is holding (the pin wheel also moves through a gate and moves forward by one pin, i.e one minute!!!!) but now the pendulum is at a higher position again – i.e the pendulum has been given an impulse! The pin wheel moves on by one pin every minute and therefore with 60 pins, the pin wheel does one revolution every hour – the minute hand! Add the daisy motion to this and you have your minute and hours! I`m not going to rush this but to be honest, with no gears the parts don`t look overly complex so I expect to make good progress. I expect like I have experienced with my Webster IC engine, most of the time will be in the troubleshooting, getting it to run! Materials:This is the brass sheet required for the construction along with Wildings build book, some spring steel and the nylon chord.

Just some proof of the validity of my story about the 2″ dia steel bar coming from my original purchase of these materials. I don`t know why I never sold this piece and equally don`t know why I didn`t order this piece when I re-ordered the materials last week. Freaky…. notice the news paper it is wrapped in – 2004!

Here is a piece of paxalon rod and Invar. .

The rest of the materials – lots of imperial bar stock is on order still from College Engineering Supplies. It has been a week now but I`m guessing the order is quite fiddly with lots of different sizes in small quantities. Hopefully it`ll arrive this coming week. So I made a start. The first job is to simply prepare the back plate which was £22 of brass! The plate is 9″ x 6″ but the material is 13-14″ x 6.1″ as the excess is used for something else. First job was to cut off the excess. I prefer to spend time setting it up on my mill and cut it that way as it leaves a good finish and I prefer it to sawing., besides my saw wouldn`t cut all the way so I`d need to meet from either side which would be doomed to failure. This worked really well using the brass square section to clamp it onto a pair of parallels.

I filed the edges square which took a while but worked really well, nice and square. The file is slowly becoming my friend!

The next job was to drill three 5/32″ mounting screw holes, 2 at the bottom and 1 at the top and then soft solder some 1/16″ thich washers to the back of the plate to lift it away from the mounting board when screwed down. I didn`t have any 1/16″ washers and although it isn`t critical, I decided to make some. Here it is soft soldered and quickly tidied up. Needs a little more work to remove a little excess solder but has turned out well so far.

Pendulum Mounting Bracket: Got a little more done this past few hours. With the back plate now ready to hold some new parts, the first one is the pendulum bracket. I cut a couple of pieces of 1/8″ brass sheet and used double sided tape to secure them together. Machined them square and started profiling them

Still together I drilled the support holes and filed the top suspension “V”, finally separating them:

I then machined up the centre piece and now I`m left here:

Wilding now says to clamp these side piece together to the centre to drill through and tap so they can be secured.

I then aligned it square:

And now it sits nice and square in the top corner – the first part mounted on the backing plate!

And now it sits nice and square in the top corner – the first part mounted on the backing plate!

Next onto the pendulum suspension…. I managed to make the lower pendulum clamping bracket this evening which was a really nice combination of milling and turning. The part will hang off the bracket I made earlier with the pendulum rod screwed into the bottom. I started with a rough cut 1. 1/2″ length of .5″ square brass and milled a 1/4″ slot at the end.

I then rought cut a 1/4″ piece of guage plate, milled one side flat, butted it upto the edge of the groove I`d just cut, clamped together and bolted it through:

Tidied each side up in turn, stopping just short of the brass width:

I then transfered the work to the 4 jaw and centred it. I drilled the end 2.BA for the pendulum rod and turned down the square to round (I think this is just for looks)

Finally finished with a countersink on the clamping steel and used a nice 4BA screw. Here is the part finished:

The spring still is clamped between the brass and steel sections. The other end connects to the pendulum rod. Tomorrow I`ll try and get some done on the spring steel and top clamp… Pendulum Suspension: I was reading about cutting the spring steel this morning and apparently you punch it out. As per Wildings instructions, I folded over a strip of brass, marked out on both the template and the spring steel:

I made this punch but stupidly have rounded the edges so I`ve not ended up with a good clean cut. It worked really well and I did get a disk, but it has pressed the edge a little.

I then went on to make the top clamping bracket: The whole lot suspends from the bracket I made in my last post. The plans call for 2BA studing but I just cut down a long bolt, turned down the ends and rounded them:

Cutting off two 7/8″ brass disks 1/16″ in thickness. I then went on to mill a flat on the top and tap one 10BA and the other drilled clearence

Both John Wilding and GadgetBuilder stress the importance of the spring steel being square to the brackets. Wilding suggests this method to lock it

Both John Wilding and GadgetBuilder stress the importance of the spring steel being square to the brackets. Wilding suggests this method to lock it all down square:

And the final setup:

and now fitted with the invar pendulum rod.

Pendulum: Got the pendulum up and, well, swinging tonight! Hacked off a piece 4″ (just over) length of 2″ dia silver steel:

Drilled it through 6.5 mm to make an oversize hole for the pendulum rod

I re-drilled the top 8mm to a depth of 10mm and then I turned up some bushes out of brass for the ends with a 6mm bore to accept the pendulum rod

The hole pendulum unit was assembled:

And then a picture for those of you that don`t know what a pendulum swinging looks like go.. in action:

Hey, I had to include it!! Photo is rubish but here you

I`m going to need a quick stand so I can easily remove the brass back plate from the wall and then place it back on to test. I don`t know if there is any way of doing this without the faff of unscrewing it each time. So a bit of time tidying out my workshop tomorrow and then I`ll make a start on the count wheel. Then I`ll move back to the pendulum pawl brackets and then hopefully I should be able to get a minute timed out by the pendulum dragging the count wheel forward….obviously at that stage the clock will stop after a few mins because it`ll get no impulse but I`ll be able to check the general mechanism is working! Count Wheel: I`ve spent a little while finishing this count wheel but managed it last night! The count wheel has these ratchet like teeth so that as the pendulum swings, the gathering pawl/wire slides up one of the slopes and drops behind a notch pulling the count wheel around one place. I started with two rough cut pieces of 18g CZ120:

Made an arbor and chucked them both up:

Turned them down to 1.5″ diameter:

I then made my profiling tool to cut the teeth, a 60 deg cutting tool but I needed a flat parallel to the mill bed when mounted:

I then unscrewed the chuck and mounted it on my rotary table on the mill. It managed to get out of true when I did this in my previous efforts so I set up a DTI just to check it was running OK – which it was this time! I must have knocked it last time, but my arbor was also longer in my other efforts which may not have held as well. Also, it sounds stupid, but I think there was some vibration last time and the chuck wasn`t tight on the rotary table that is why it didn`t cut properly.

I then centred the wheel – made sure by making a whitness mark, moving to the other side and checking it was at the same height – you can just make this out on the photo

I started cutting the teeth!

Wheel teeth cutting complete and worked just fine!! :ddb:

I was then in two minds – remember I cut two wheels at once since it is thin 18g brass, the two together provided support for one another. I didn`t want to cross them out together as I risked spoiling them both if I failed. So I opted to remove one (as shown above) and remount the other on the chuck arbor and mount it under the rotary table. My Dad then kindly helped me with some nice math calculations so I could calculate how many degrees I needed to rotate the rotab with the cutter down and then lift the cutter for so many degrees and then back down etc to cross the wheel out..

Then it was time to file it all square. I appreciate I could have got much more accuracy using the rotary table for all the crossing out but I decided to saw the little pieces out and file to size as described in the plans. This is the setup I`ve seen people use – a long wooden board, a groove cut and you sit on the board with the work nicely on platform infront of you …worked very well

And after 20 minutes of rough filing I`ve got it coming to shape.

OK OK – it needs a lot more filing to make it look neat and quite a bit more work on burnishing the teeth but I`m nearly there…. I cut the deeper tooth and made the mounting arbour this evening. Tapping the 12BA was a little hairy and I just managed to get the distance right so that the screw heads didn`t foul the wheel mounting post :ddb: Still needs more sanding and burnishing the top of the wheel but I think I`ll do that in a few evenings.

I must admit, I`m pretty please with it!! :ddb: Count Wheel Pillar and Bridge: I started working on the clock again this week, didn`t get very far but here is an update on the bridge plate and pillars: Marked out the plate:

And roughed to shape with a file:

I then went a made a depth stop for my lathe as described by John (Bogstandard) in his “backstop” thread on madmodder.

With the backstop, it was easy to get two the same length solving all previous issues when I`ve tried this!

I then drilled a tommy bar hole in the end to ensure we can tighten these onto the back plate:

The bottom end of the pillar is threaded M3 but I had concerns that I couldn`t thread it all the way using a die, I always end up with an untreaded stub so consequently it won`t screw down to the shoulder. I normally just nick this with a parting tool but with only 1/8″ of thread, I wanted as much thread as possible. So instead of threading, I drilled and tapped and using loctite, glued in two M3 screws, letting the glue dry and then cutting the thread to size:

As suggested in the plans, to profile the pillar I screwed it into a piece of scrap barstock threaded in the lathe and could then work on the entire length.

And the two finished:

And the pillars and bridge mounted on the backplate:

Next thing is to drill the pivot holes and so it is suggested I remove the pillars and drill through the bridge and packplate together to ensure they are aligned!

Back Stop: I managed to get some snaps and make a little more progress :ddb:, although a step back at the same time :palm: Here is the wheel mounted on the clock:

I then started the count wheel arbor:

I didn`t get any photos of burnishing the pivots on the wheel, so here is my simple setup I used. This was actually on the count wheel pawl pivots

Here is the count pawl and pivot

…and then with the bracket, please bear in mind it all needs polishing. Notce that the side frames are also pinned to keep the pivot holes aligned.

….. I did say some bad news, that being that my deep tooth is too deep and the angle of the tooth too steep so that the pawl gets stuck when it drops into it. I`m a bit dissapointed but things look like they are going to work OK ! I continued making the back stop and got to a stage where I could properly test the count wheel: httpv:// I don`t often divert off the plans that often but I was having real problems with back stop and I figured it was all down to its position. The plans call for the backstop to be mounted alongside the count wheel on the bridge piece as I originally built it:

However the angle at which the backstop engages when in this position is not at all ideal as it bears down heavily on the wheel and it also doesn`t slide over the teeth as easily as it would if it was more horizontal or more parallel with the tooth flats, similar to the position of the opposite gathering pawl. I therefore made a new mounting bracket fitted from the bridge screwing point and the screw at the back is a counter balance, the nut allows more fine adjustment of this. This really reduces friction on the count wheel. I made this modification much earlier on with an ugly temporary backstop that you may have seen in the videos of the running clock. I would certainly recommend this modification:

Pin Wheel: I next went on to make the pin wheel over the last couple of nights. Still not finished but getting there, just needs pinning. Ok here goes:

Before drilling, I needed to check the drill size was ok for pinning all 60 x 1/32″ pins without the need for glue. I used a 0.75mm drill in a piece of test material and it worked really well. I used the drill as a press

Then setup the wheel on the CNC rotab and drilled the holes

Took a bit of a risk as I feel I can make a better job of the crossing out on the mill rather than by hand. However, the arbour wasn`t strong enough so risked moving it to another bigger chuck. I managed to centre it and of course checked it before I started any cutting but it worked out well.

Now all the front face and crossing out needs fully cleaning up. Problem is that when it is pinned you can`t really get at it all so the wheel needs totally finishing before being pinned.

Finally after hours of trialing various methods I managed to get a method to cut the pins down to about 20 seconds a pin. Knocked up this little punch. Both parts are silver steel and hardened. The small bit is obviously the punch and the large part has a matching hole of dia 0.22″ (iirc) which is the length of the pin required. The large section is also cross drilled 0.8mm

Just got given a set of letter stamps so thoughts I`d try and use some for the first time putting my initials on the new tool

I milled two flats on the bottom of the large section so it can be held in the vice. Setup like shown below with the red box to collect the pins:

I milled two flats on the bottom of the large section so it can be held in the vice. Setup like shown below with the red box to collect the pins:

To pin the wheel I took a small piece of steel bar, drilled 0.8mm ensuring that with the pin pushed in fully, a small length was sticking out to push all the way through the brass of the wheel. I put a few tiny magnets on the pin holding guide to hold the pin in place which was just coping how “Gadget Builder” did when he built this clock.

Complete pinned wheel !!

Next to make the arbour and supporting frames and get it mounted on the clock. Then back to remake the count wheel !! Made the pin wheel arbour tonight which also doubles up as the drive pully. There is a few issues with this related to the type of line I ultimately use. Basically, the drive wheel obtains it rotation from the falling weight, simply by the friction of the line pulling over the pully. As you can imagine, this is tricky as if the angle is too sharp in the V groove of the drive pully, the line can bind and if too narrow, the line will slip. I chose to follow more advice by John (Gadget Builder) who has suggested to me I try 45 deg as Dr Woodward did and use monofillament line. I can always open up this angle and try builders line if I want to, but couldn`t go the other way unless I remade the pully. Set about cutting a 45deg V form tool and cutting the pully V:

Collet and arbour complete:

And complete wheel on arbour with a bearing with 1/8″ ID stuck on the end just to check they fit

And complete wheel on arbour with a bearing with 1/8″ ID stuck on the end just to check they fit

Plates next and then get the wheel mounted. Here is the bridge for the pinwheel: Both wheels mounted and some pleasing filing on the arc!

I also decided to make the impulse pawl and then all pendulum parts are complete.

And mounted on the pendulum…

Gated Detent: I completed the “gated detent” earlier today. This is a critical part, it allows a single pin on the pin wheel to slide through the gate but catches and holds the next pin until the next impulse. The paddles were made from 0.02″ steel shim but I couldn`t find anything suitable, so I butchered one of my very cheap shim gauges. The price of the gauge was no more than I would have been willing to pay for a suitable piece of stock. It was a pain because it was hardened or stainless? I could only cut it with a dremel grinding disk which worked quite well.

When an impulse occurs, the paddle tips down and a pin slides along the top of the top blade and falls throught the gate where it catches on the lip sticking out on the bottom (the bottom paddle). As the deten tips, it tips off the pin from the bottom paddle/detent which then accepts and catches the new pin. It was very small, the bottom paddle sticks out only 1/32″ but can be adjusted by the bottom screw. Next onto the mountain brackets. Here is the adjustable bracket that holds the gated detent in position:

..and mounted;

Now I`ve moved onto the deflector piece: Roughed out:

and then filed to shape with pawls attached:

Hopefully get this piece mounted in the next few days… Initial Run: I`d made all the parts required to test the mechanism and I must have spent near 10 hours just tweeking the setup to get it to run. Finally, just as I was giving up again for the evening, I had a brain wave based on the advice and suggestions given to me by John/Gadgetbuilder; I made some changes and off it went! I`ve many corrections to make to the working mechanism and you will spot a huge error in the working of the backstop – notice when the backstop engages the large tooth,it jumps/catches on the count wheel. I think this is just the position of the backstop pawl but I wanted to leave it and let it have some time running. It didn`t effect the physical mechanism but it will cause errors in the time, so it will need correcting. I have a much much better idea now of how this all fits together so I`m now very confident I can get it working more smoothly! Here goes, I just did my best to video it in bad light at this time of night. httpv:// 1. The pendulum swings 40 periods each minute, gathering a tooth on the 40 tooth count wheel. The count wheel therefore rotates once every minute and so the seconds hand could be placed on this wheel but it would turn in reverse. Consequently, Wilding didn`t have any seconds indication but Woodward placed numbers on his count wheel to approximate the seconds. 2. The count wheel has a single deeper tooth than the rest. When the count wheel pawl (the top wire on the pendulum) drops into this deep tooth, it engages the vertical wire on the deflector piece. At 56 seconds in the video, you can see the count wheel pawl going over the top of the deflector and imagine how it interacts when it hits the deep tooth. 3. The deflector therefore tips anticlockwise and this causes the diagonal piece of the deflector piece to obviously tip down as well. You can see the deflector mounted on the backplate below (the other bit you can see at the bottom of the deflector is a stop to stop it tipping all the way back at rest). 4. This bottom piece of the deflector bears down on the lower wire from the pendulum (the impulse pawl) which engages a tooth on the pin wheel. 5. You can`t see this on the video but there is a small weight (a large allan key!) hooked directly onto a tooth (at about 3 oclock position) on the pin wheel. The tooth on the pin wheel is engaged with the bottom lip of the deflector piece. When the impulse pawl pulls the pin wheel back by a fraction, this releases the pin from the detent and the weight on the pin wheel, which in future will be a proper weight and chord, pulls the pendulum back to the right and gives it the impulse! 6. There are 60 pins on the pin wheel and so this rotates once an hour giving you the arbor for the minute hand. A fancy “daisy motion works” will then need building to gearlessly reduce down this motion to 1 turn per 12 revolution of the minute hand/pin wheel arbour. Hope that in some way explains how it runs! Some more pictures for you of bits I`ve taken as I did a quick polish ready for this test assembly. Back plate.

All the bits ready for a quick polish. This isn`t a final polish, I just needed everything clean to get it to run.

Count wheel

Back stop

I made another count wheel with shallower teeth a few days ago but managed to get the original one working so didn`t bother using it yet. I might try this one as I expect that the back stop is jumping because the tooth is overly deep on my initial wheel I`m using.

Pin wheel and deflector piece:

same as above, with the gated detent:

Well I can now go to bed much more positive than I have been doing for the last few weeks! Pulleys: I got the weight pulley system together which took a lot longer than I expected! These little things were tricky to make! They each run on a tiny bearing;

Because they are only about 3mm wide, I found it really tricky to have a blind hole to a press fit. It was too tight and I ended up killing the little bearing trying to press it into the housing, or it slipped into place. Consequently I had to loctite the bearing into the housing:

Then I made some small shaft for them to sit on:

I managed to get it all hooked up. I then needed a way of checking the weight required in the both the master and jockey weight before cutting any 2″ dia steel to size! Both Woodward and Wilding explain that the jockey weight and master weight are dependent on the line used and pulley setup. Woodward used nylon fishing line but this seems to offer no resistence. A kind chap from the NAWCC forum sent me a length of nylon line but like Wilding and Gadget builder, I couldn`t get enough friction and the line just slipped. I am currently using builders braded line and it is working well. I`ve used a coffee jar full off steel offcuts as the master weight which allows me to adjust the weight. I`ve still not got this quite right. I think my jockey weight it too heavy at present. I had the clock running for about 45mins but the pendulum slowly slowly slowly dropped, indicating the master weight on the centre wheel isn`t heavy enough. Woodward did use a much heavier weight than Wilding, and I`m currently using the smaller weight recommended by Wilding. Tomorrow I`ll adjust this, but the clock is running with the pulley…I just need to get the weight and jockey weight sorted and then I can move to the dreaded daisy motion!!!

In a desperate attempt to get the clock running, I`d used a hoop on the coffee jar lid which wasn`t allowing the line to slip correctly and if you look at my picture above, it was pulling the line down off the pin wheel at an angle. I made a very rough pulley based on Wildings plans. I will need to shape and finish this to make it look more elegant, but it will transfer to the master weight when I`m happy with everything.

Once this was on the clock, I found most of my problems went away but I still struggled with pendulum losing momentum. Woodward suggested 1400g master weight with the jockey weight being 60% of this when used with nylon monofilament line to stop slippage. Wilding used only a 700g master weight and although he explained Woodwards ideas, he admittedly used a far smaller jockey weight than the 60% suggestion. I was using about 850-900g in my master weight (because I was trying to get the pendulum to have a bigger impulse) and about 200g in my jockey weight. Wilding did mention you could use less “if you could get away with it” and because the braided builders line has much more “grip” than any monofilament fishing line, I experiments to see what the minimum I could use was. Using too little jockey mass and the line would slip and the master weight would slowly fall, however using a small M10 bolt and adding nuts as extras weights, I got to about 50g for the jockey weight. This made all the difference and my problems with impulse had gone! The clock was running… but that lead to another problem…!!! With the bigger impulse, the backstop pawl started jumping again! This is something John (gadget builder) and I have been discussing for a while but no amount of bending of the wire could stop it. The position Wilding suggestions will clearly work but even if you don`t get the jumping I was experiencing, this low position of the backstop is not ideal. Really the backstop should be acting in a more horizontal position like the count pawl is acting in on the pendulum rod. This will allow it to easily lift and drop off each tooth, especially the deeper one I was having problems with. John suggested a better position for the bridge would actually be at a 30 deg angle! This wouldn`t look great in my opinion, but the higher position of the backstop would at least reduce the force on the count wheel. This was irrelevant anyway as it was installed on the clock! The other option would be to take a bracket off the right bridge pillar and mount the backstop on there! So that it was free to move I used a small bearings. To reduce friction even more, I intentionally increased the length of the backstop wire and hooked the back end so that I could add small washers as weights to counter-balance the backstop. This made a MASSIVE difference, both the position and the counter balance. The position stopped it from jumping all together and by adding the small weights, you could tell friction was reduced because the back stop became silent in action! :ddb: Now, I made this as a quick job and haven`t shaped it or polished it and clearly I`m not going to use washers to counterbalance the system on the final thing!!! I just stuck it on to see if it would work, but once I`ve made this look OK it will be installed. The bracket needs rounding at both ends and making much narrower:

and making much narrower:

It has been running since 10am this morning which is about 10 hours 30 mins of running time. Fingers crossed it is still going tomorrow morning!!

This will later be modified to a doubled pulley line to get less drop of the weight per day… Double Pulley Modification: It has been over 2 weeks since I updated and I can honestly say I`ve been working none stop on the clock with very little to show. The pin wheel had been damaged and some of the pins needed removing and resecuring in place which took a few evenings. I also have been doing a bit of work on the daisy wheel but nothing to show yet. However, I have made more progress on the weight setup shown below. I`m doubling over the weights to give me a shorted pendulum drop per day. This requires two more pulleys making (shown in the second to last picture) and also a new jockey weight with a pully. Here goes, sorry, too many photos really but I took them so may as well post them… I took this piece of brass someone kindly donated to me a few weeks ago and turned it to a good finish.

I then cut a groove in the end:

I then took a piece of brass bar to make the end cap. I always always struggle making something a friction fit, I`m always either just too big or just too small. So this time I turned a little lip at the end and turned it down until the bar would “just” fit with a bit of pushing into the groove. I then backed out 2 thou and parted off a disk:

Used a bit of loctite and hammered it in place. Popped it back in the late and faced the end flush. You can`t see the joint!

I then made a screw on lid so that I can add lead weights as needed:

The hole in the lid is for a lever bar to screw the lid on and off, which is why the drill is in there… a good way to snap drills

I then made the pulley for on the top.

Made a screw for the pulley axle:

Then I made the pulley holder which I decided was too big, so the black mark is where I decided to chop it in half!

Looks much better now without the top piece but it needed a hook to tie the central line. I did a little more, decided to make a hook to fix my “issue”. Looks ok imo and I think I prefer it to the solid body. Maybe the hook could be a little smaller?

Here is the new pulley layout:

I`m going to have to make my weight narrower than I thought. Adding the extra loop in the pulley setup has thrown the chords nearer so they will clash if I make the master weight much wider than the dia of the master weight pulley. The clock is running now, so once I have the weight that works, I`ll make it from brass solid.

It has been running now for another 24 hours and there must be more friction with this new pulley setup so I could have a much heavier weight which moved nicely to give the pendulum a “good” impulse. Daisy Wheel: I made a massive step this evening. The daisy wheel has been a source of problems for weeks. Infact, the truth is my first attempt was simply to prove that the principle worked but I`ve added a bearing, changed some dimensions to fit my clock and it has never really be right, often skipping hours or jamming up. So I went about planning cutting a new wheel. I`ve been buying lots of sheet brass for my project and it is causing a dent in my wallet. With my new found “parting” skills – I stumbled across a 2 3/4″ brass bar at the scrap yard, 5″ long. Even with enough to hold in the chuck jaws and the waste removed with parting. It is going to be much cheaper parting off brass blanks from this rather than cutting disks from sheet brass. Anyway, I cut myself a blank and then decided the ID must be 34mm to allow the pin wheel to go to full depth in the wheel and the outside diameter 40mm to give enough wall to each “V” to allow the pin to bounce/drive properly. I`ve cut the other two attempts using a form tool in a fly cutter as I would when trying to cut a gear but this wheel is really thick at 2.5mm!! and there is just too much vibration and material. The plans say to cut by hand anyway so I decided to mark out and cut the notches. I had to work out my angles and then used my CNC divider to mark the points, joining them up with a ruler:

I cut each one by hand:

I then checked all the markings and filed to size which took a good few hours. The pin wheel was binding and I thought all was lost but then realised that the 75deg angle I had used, hadn`t taken into account the radius on the “full” daisy wheel plans – I`m cutting my daisy petals short on purpose as they serve no use other than providing an opportunity for the pins to bind! So I rounded the corners. It looks more like a daisy now but the plans call for accurate radius on each petal as though the pin is following the tips of the petals. I`ve just rounded mine up to look nice, the important bit is the 75deg notch along with the slight radius of the edge leading into the notch. [img][/img] I then speeded up the process of checking the daisy motion by putting it into the lathe and it seemed to work just fine! I`ve installed it on the clock and it has been running for 3 hours with no problem, which is longer than my previous two attempts! I`ve got a half decent feeling about this one… :ddb:

Just the master weight now….although a clockmaker who has given me a lot of advice doesn`t like my jockey weight and pulley so it looks like I`ll have to remake it! The I`m on to working with the brown woody stuff!! Glass Face: I`m terrible at design and getting things in proportion, so for the face, I mocked it up in CAD and then made it out of a card template just to see what it looked like:

(the bar code is a nice part of the design

Happy with the size and mounting positions and also getting the nod approval from a few of the forums I visit, I went ahead and ordered a piece of glass to be water jet cut. I had to take the glass to them, just normal picture frame float glass. Being so cheap, I actually took them 3 pieces “just incase”. I was very pleased the next day when they rang me to tell me all three had been cut for the price I thought I was paying for one. At least this now gives me one totally spare and then two to try different designs of numbering and marking. In my opinion, the glass looks amazing in person…pictures do it no justice. It looks plastic on the photos but is clearly glass and has a green edge in the light! I couldn`t be more pleased.

Perhaps a little over the top, but I made a little video as sometimes the video function on this cheap camera gives a more life like shot that the still photos…gives you an idea! httpv://

I need to find a dial painter now! Case and Initial Assembly: You`ll notice, hopefully, that it has all been gold plated. I`m never very pleased with my work and I must say this looks smashing and it is so difficult to get a good picture of it! The gold is so well polished and reflective that I just get glare but then with such dull winter days, I still need a flash! Anyway, I think you`ll get the idea. Here goes…hope you like it. Clock mounted on the wall without weights and pulleys

I`ve just finished making two brass countersunk washers to replace the large ugly steel washers but I took the picture earlier today:

I think this shows off the gold plating the best! I`m very please with it and a good skill to have learnt and the kit wasn`t much more than I`d have paid

I think this shows off the gold plating the best! I`m very please with it and a good skill to have learnt and the kit wasn`t much more than I`d have paid to have it plated by someone else.

So things to do/finish: 1. Fit the new brass washers. 2. Blue some of the screws and find some M4 screws that can be blued! 3. Make new pulleys for the weights – started this a few days ago and spoilt them both!! 4. Get the new dial numbered. Feels good to have it on the wall and running!





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Gearless Clock

Home Overview Pendulum

* *         Last Modified   07/03/52037 18:00:08

Building Woodward's Gearless Clock Click to Enlarge

Rate Adjustment Count Wheel Escape Pin Wheel Daisy Wheel Maintaining Work Weights and Drive String Builder Notes Setting Up Further Adventures Clock Case Time Keeping

Escapement Video Loop Daisy Wheel Video[25.01.2020 21:44:25]

Gearless Clock

After reading Dr. Philip Woodward's "My Own Right Time", I was inspired to build a copy of his gearless clock. John Wilding's construction book for this clock provides details that simplify construction although (as usual) I made some "improvements". The minimal number of parts and their unusual construction made this a delightful project, enhanced by the fact that this clock obviously wanted to run. The picture above left (with yellow string replacing the stylish pink drive string) was taken during a trial of the weight/drive system. The temporary dial is paper, just taped in place for evaluation. The pictures above show a practice case made from poplar, done to improve my (nonexistent) woodworking skill and the purchased chapter ring. Morning sunlight reflects off a tiled table in our living room and through the clock producing an interesting shadow on the wall. This shadow occurs for a couple weeks around spring solstice - leaves are still on the trees at fall solstice so no shadow then. This clock may never be complete... but it is getting closer, always a few little details left.

Overview[25.01.2020 21:44:25]

Gearless Clock

Dr. Woodward's gearless clock design is novel in many ways. It is a modular design where the various functions are easily recognized and connect to other functions in a way that is ingenious but clear on careful inspection, leaving the observer with a "wish I'd thought of that" feeling as each facet of its operation is understood. Some of the connections between functions are made up of wires with counterbalance weights so gravity returns them to their default position - a most unusual implementation method in a clock. This design strips away the mechanical complexity of a typical clock, leaving the essential details implemented in an unconventional but very functional way; it's entertaining to watch it work and a challenge to understand the operating details. The pendulum in this clock connects directly to a ratchet wheel via a pawl which indexes this count wheel for each swing of the pendulum; a backstop pawl ensures the wheel indexes in the correct direction at each swing. There are 48 teeth on this count wheel, one of which is deeper than the others; this deep tooth causes the pawl to move a deflector lever connecting to the minute module. The minute module has a hook connected to the pendulum, where the deflector lever noted above depresses this impulse hook to engage a pin on the minute wheel. The timing is such that the hook first pulls the minute pin wheel backward a half minute, releasing the escape. This allows the pin wheel to then impulse the pendulum as the pin wheel moves forward by 1.5 minutes, limited by the escapement; pendulum inertia carries the hook a little farther, releasing the hook. This hook and the lever which originated the pendulum impulse are both counterbalanced so they assume their disconnect position until the count wheel completes another turn. This gearless clock is unusual in that it impulses the pendulum only once a minute; the interaction of the impulse hook and the escapement is most ingenious, producing a sound similar to that from a common pendulum clock arming to strike. The escapement remained a bit of a puzzle to me until I built it and saw it operate. Each minute the pin wheel is pulled backward slightly; this releases the pin captured by a lip on the counterbalanced escape so the escape pops upward, landing against the next pin; this pin then slides along the shelf as the pin wheel rotates until it drops through the slot and[25.01.2020 21:44:25]

Gearless Clock

is captured by the lip, completing the cycle. The escape is shown in a picture below but it is best to see Dr. Woodward's book for a good explanation - or just build one... The YouTube video of the escapement's action shows a few seconds before and after an impulse to help understand how the escape works. The ticks heard in the background are from two other clocks in the room but the impulse sound from the gearless escape can be heard clearly. The string has a black thread running through it allowing the (small) movement of the weight at impulse to be seen at the right edge of the picture. Power to drive the clock is supplied by a weight attached to a string wrapped around a pulley on the minute arbor. This clock isn't "wound" in the strict sense - the drive weight is simply lifted and the resulting slack in the string is taken up by a second (jockey)weight. This second weight is a fraction of the weight of the drive weight, causing the string to bind in the pulley, much as a bollard is used to amplify friction when controlling a ship at a pier. Pulleys are used to direct the drive string path. While winding by lifting the weight is quick and easy, lifting the weight too rapidly can pick the string off the pulley so one must proceed gently while "winding". The daisy wheel motion work module is driven by the minute shaft and is easily removable by taking out the retaining taper pin on the minute shaft. I'm still working on minor details. The biggest thing left is to build a walnut case for it. This clock is a work in progress; some pictures and text follow, more may be added later.

Pendulum As with many of my projects, this clock was made mostly from scrap plus a few bits of purchased material. I had a nice 4" long piece of 1.25" polished stainless tube so I filled it with chopped up lead; weight was 2 pounds - I used this initially as the pendulum (shown in some test pictures) even though it was only half the weight specified by John[25.01.2020 21:44:25]

Gearless Clock

Wilding. In many clocks pendulum weight isn't critical but here it is because this clock uses larger, less frequent impulses to keep the pendulum moving. With this lighter pendulum storing and dispensing this energy, the single impulse each minute causes a larger than acceptable change in pendulum swing. When the swing is too large the pawl gathers two teeth on the count wheel for a couple cycles after the impulse causing the clock to gain time. Reducing the impulse enough to eliminate this makes the clock unreliable. So, I found a piece of 2" steel round and made a pendulum to John Wilding's plan - makes operation reliable and tolerant of reasonable variation in drive weight. With the original light pendulum the decay in pendulum swing between impulses was easily seen but it isn't obvious with the heavier pendulum. The initial pendulum rod was fiberglass composite with the glass fibers parallel to the length; this was eventually replaced with a carbon fiber rod for reduced temperature coefficient. Carbon fiber, according to what I found on the net, can have a positive/zero/negative temperature coefficient dependent on how the fibers are laid up - the rod I purchased from the hobby store seems to have near zero coefficient. The parts holding the count and impulse pawls were from aluminum except the counterbalance for the impulse hook is brass - my notion was to minimize the weight above the pendulum which the fiber rod and aluminum parts help accomplish. The aluminum pawl holders didn't look good on the pendulum rod so eventually I replaced them with brass holders. In replacing the count wheel pawl I used 0.025 music wire and added a partial counterbalance to minimize the sound as the pawl drops.

    Temperature Compensation - An Obvious Problem with No Obvious Solution A threaded section with a rating nut supporting the pendulum, as suggested by Wilding's plans, would add additional temperature sensitive metal lengthening the pendulum rod. My thought was that this would make temperature compensation more difficult so I opted for the method below where the main item requiring temperature compensation is the suspension spring - the carbon fiber rod has near zero temperature coefficient. A rating nut works well for accuracy of a minute or so per week but I wanted to attempt better accuracy than this - which requires much more fussing.[25.01.2020 21:44:25]

Gearless Clock

My assumption was the pendulum period would lengthen with increasing temperature so I drilled the top half of the pendulum to just pass the rod and drilled the bottom half larger so a thin aluminum tube surrounding the rod could be installed. A pin through the pendulum rod 2" below the pendulum supports the aluminum tube; by supporting the pendulum at its center, expansion of the pendulum itself with temperature should be neutralized so the aluminum's expansion need only cancel the suspension spring and pendulum rod expansion (it says right here :-) The thin aluminum tube was filed to length (1 thou = 2.8 seconds) to set the rate a few seconds a day slow; washer-like shims below the aluminum tube are then used to coarsely adjust rate. Adding small weights on top of the pendulum will raise the pendulum's CG and speed it up slightly - easier and more precise than a rating nut. Similar to the way Big Ben is adjusted... This is a nice theory that compensates for part of what occurs in practice. Slow changes in temperature are handled reasonably well by this but my clock is mounted on an outside wall that faces west (heated by afternoon sun and cooled by winter winds) plus we use setback thermostats so the room temperature can vary by 20F within a couple hours in winter; further, we have hot water heat so a radiator happens to extend directly under the clock, further confounding the issue. In summer, temperature swings are slower but can be larger, perhaps 35F in a day. Transient temperature response of the pendulum system is difficult to evaluate in situ. The upper end of the pendulum rod, including the suspension spring, is enclosed in the case - reducing the rate that ambient temperature affects it. The lower end of the pendulum rod, including the pendulum and the aluminum temperature compensator, is outside the case exposed to ambient room temperature and also moving which aids heat transfer. In addition, the aluminum temperature compensator is partially within the pendulum so its temperature response to ambient is further muddled. A better location or a full size case with temperature control aren't going to happen so approximate compensation for slow temperature changes plus setting the rate so it averages out on a weekly-to-monthly basis seems like the best approach.[25.01.2020 21:44:25]

Gearless Clock

    Rate Adjustment Rate adjustment is a successive approximation process. The first approximation puts the center of the pendulum about 15.5" below the top of the pendulum mounting bracket. A cross pin is positioned about 2" below the bottom of the pendulum; this pin supports the pendulum via the temperature compensation tube. Coarse rate adjustment was done by filing the aluminum temperature compensation tube to length (as noted above). A steel washer with a recess to prevent the cross pin from moving supports the tube. It's easy to go a little too far when filing the tube to length. To raise the pendulum a bit one adds a washer-like shim under the tube. These shims are trickier than they first appear. Initially, I would calculate the required thickness, make an aluminum washer about that thick, then rub it on fine sandpaper to fine tune the thickness. Unfortunately, the thickness wasn't uniform so it wasn't clear exactly how much it raised the pendulum - this became more of an issue as the rate error decreased, of course. I accumulated a fair number of shims pursuing this method and always seemed to need one more. Eventually, I filed more off the tube so the shim thickness needed was about 0.060" -- this allowed using two shims in the 25-35 thou range to make up the needed thickness. A small pot chuck was made to simplify making shims. This chuck grips 0.350" diameter items for a depth of 0.020" so shims are now cut from the washer stock to be about 0.040 and then their thickness is adjusted in the pot chuck. The pot chuck is also used to grip the shims while polishing on a piece of fine sandpaper laid on a flat. There is still some variation in thickness but it is now only a couple tenths, where 1 thou = 2.8 seconds per day. With the rate set a second or two per day slow, rate can be increased in tiny increments by adding small weights on top of the pendulum. These can be dropped on with tweezers or swept off with an artist's brush for minimal disturbance to the pendulum.[25.01.2020 21:44:25]

Gearless Clock

Count Wheel and Deflector Initially I built the count wheel and deflector per John Wilding's book, other than revising the deflector stop for simplicity. As time went on (pun) I realized that the design of these parts made set up and tuning of the clock more difficult than necessary. The count wheel was changed to have small notches rather than fully formed teeth only one tooth was fully formed (to catch the deflector once a minute). This made it far easier to adjust the count pawl for proper operation. The picture at right shows the revised count wheel with ink near the deep tooth to improve contrast. I added hints on setting the clock up based on my experiences and as part of that described the operation of the deflector in detail. The description makes it clear that once the hook contacts a pin then the hook cannot easily deflect further so the force from the count pawl on the deflector rises sharply - this caused a groove to be worn in the area of the deflector wire that contacts the hook. I added a coil spring section to the deflector wire the count pawl contacts to limit the force applied to the hook - see the picture at left. This makes the clock more efficient (pendulum arc increased), easier to adjust, and the impulse action is slightly quieter. Eventually I changed the design of the backstop pawl to make it more symmetrical with the count pawl and easier to adjust (also linked above). Builders considering construction of this clock would do well to consider all three of these changes - they make it far easier to achieve reliable operation. At the very least, include the deflector spring.[25.01.2020 21:44:25]

Gearless Clock

Escape Pin Wheel The escape pin wheel is the most difficult part to build in this clock. Fortunately, my mill's DRO has a "bolt circle" function which made it straight forward, if tedious. Here, the 60 holes (one for each minute) are being spotted using a shop made 0.022 spotting drill, spade type. This was followed by drilling with a 0.029 twist drill. Click to Enlarge

The escape wheel was pinned using a shop made tool having a hole 2 thou larger than the 0.031 pin. The magnet on the side of this tool holds the pin in the tool until it is set. When the pins were pressed through the wheel, the steel block stopped them at a uniform point so cleanup of the back per Wilding's book wasn't needed. I cut all the piano wire pins to length in the "whack-bang wire cutter" from my prior clock project, then held them in a pin vise mounted in the 7x12 chuck, filed the ends flat and chamfered them, (the insert end more than the other) with a diamond file.[25.01.2020 21:44:25]

Gearless Clock

The completed escape pin wheel, OD= 3.125".

Escapement test - the escape is gravity operated so moving the pin wheel by hand cycles the escape. The count wheel/backstop and pendulum connection were tested previously (no picture) where the pendulum will operate the count wheel for a little less than 2 minutes.[25.01.2020 21:44:25]

Gearless Clock

A test driven with weight hung from pin wheel, runs for 15 minutes - until the weight hits the bottom support. This simple arrangement (a nut, washer and bent paper clip) allowed adjusting the basic operation of the clock without the complexity of the weight drive system. This test weight is also a convenience while threading the drive string through the works, keeps the escape from jiggling around - but isn't needed once the sprag is added.[25.01.2020 21:44:25]

Gearless Clock

Ran the drive section for a couple days without the motion work, then added it as shown below. Surprisingly, the motion work didn't seem to affect operation - pendulum swing didn't diminish due to the added load, as I thought it might. The weight drive required some tinkering to get it right although the weights per Wilding's book provide a good starting point. I used 1.5 pounds for the drive weight and 120gm for the jockey weight. The nylon string slowly slipped on the pulley so I increased the jockey weight but it needed about 1/3 the drive weight to stop slippage. Winches on sailboats often have roughened surfaces in their scaled up application of this principle so I roughened the sides of the "V" drive pulley to improve traction, which worked well. This was done by mounting the pulley loosely on a small round then rolling the pulley on this shaft using pressure on a needle file in the "V"; this left an imprint of the file teeth on the sides of the "V", not deep but enough to improve grip. Fine carbide paper was then used to ensure there weren't any sharp snags left by this operation. The clock takes some time to stabilize operation after start-up. Initially, one deflects the pendulum so the impulse hook is moved one escape wheel pin space from rest and releases it. It then takes several impulses (minutes) for the pendulum swing to reach equilibrium. Generally, after 3 or 4 impulses one can tell from watching the count wheel pawl and[25.01.2020 21:44:25]

Gearless Clock

backstop pawl vs the teeth whether the impulse is correct - this from several hours experience watching how it works, of course.

Daisy Wheel Motion Work

This picture shows the daisy wheel motion work assembled with the temporary hands in place. This emphasizes the modular nature of this motion work, where taking out one taper pin allows it to be removed as a unit. A video of the daisy wheel motion work. Below is the daisy wheel motion work partially disassembled. On the left,[25.01.2020 21:44:25]

Gearless Clock

the minute collet with the cam and spacer; I lightly press fit the cam rather than using a setscrew. Next is the daisy wheel - the stem was soft soldered in place. The hour collet with the pin wheel, again pressed on. The hour hand collet and finally the nut for the minute hand. The aluminum hands for testing just press in place so they're not really secure. I added a spacer to take up slack between the hour collet and the minute nut, slack caused by mis-reading Wilding's dimensions for the hour collet. Never having seen a daisy wheel motion work previously, it was an education watching this one operate. While it looks simple and there aren't many pieces, I made 5 cams to get the throw right before filing the daisy petals to fit... as the world's slowest machinist, it took over a day to make these few parts. Again, the DRO's bolt circle function was a big help.

A nice feature of the daisy wheel is that time can be set forward or back simply by turning the minute hand, unlike some clocks where time must always be adjusted forward. Little force is needed to drive the daisy wheel so the light clutch friction to the minute shaft is easily overcome while setting. Initially there was an issue with the daisy wheel binding occasionally so I filed as required to eliminate these binds when they occurred; there were 4 stoppages over 2 days. When turned by hand the daisy wheel never bound up so this seemed the simplest way to find and eliminate the[25.01.2020 21:44:25]

Gearless Clock

binding. I had visions of months of intermittent problems but it has now run for over 2 months without stopping unexpectedly so it seems to be settled (I have stopped it for short periods to work on it during this time, of course). Update: The daisy locked up again on 1 October 2010. Close examination found a burnished area on one daisy petal from a pin rubbing; I filed this area down a few thou and we're off and running, again. This brought to mind a picture of a daisy wheel with abbreviated petals sent by Anthony Adams in 2007. Clearly, he found that the petals weren't necessary (just the "V's") and the petals have been the main issue with my daisy wheel. Having fully formed petals makes it easy to point out the daisy wheel to visitors but slightly smaller petals might have simplified debugging. It was difficult to figure out whether the petal or the "V" was the problem when filing to shape initially so I enlarged the "V's" a bit and this causes the hour hand movement to vary slightly - not obvious unless you're looking for it but check the video above for this effect. The pins that hold the daisy stem vertical while allowing it to move up and down were set slightly too far apart. This allows the escape release to wiggle the hour hand more than necessary so I Loctited 1/16" brass tubing over these pins to take up the excess space - not obvious that it is a patch and it reduces the wiggle considerably.

Maintaining Work A maintaining work is used to ensure a clock operates normally while being wound, where winding removes the driving force temporarily. The escapement used here, like Harrison's Grasshopper, will malfunction if drive is removed while winding. This maintaining work can provide one impulse so winding can proceed without regard to the impulse time; it will provide a second (smaller) impulse but this isn't sufficient so the count wheel will stall about 45 seconds later. Initially, my maintaining work wasn't reliable, stopping the clock after an hour or two. I added a ball bearing but it didn't help so I changed the spring from 0.040 to 0.032 music wire. (The ink drawing of the spring is because I installed it backwards... more than once.) This worked longer -the sprag clutch scheme activated and released[25.01.2020 21:44:25]

Gearless Clock

as expected but stopped within a day. The underlying problem was the pulley slowly migrated on the shaft until the sprag wheel contacted the sprag holder, adding friction; a spacer between the drive pulley and pin wheel resolved this. Unlike most clocks where the maintaining work activates only when winding, this clock also activates it once a minute (each time the pendulum is impulsed) so it really gets a workout. Dr. Woodward used some of John Harrison's concepts while designing this clock but used a different, more complex, maintaining work. My design is closer to Harrison's maintaining work, consisting of this spring plus a sprag clutch (in place of Harrison's ratchet and pawl) that prevents the drive pulley from turning backwards as the clock is "wound". This required separating the drive pulley from the escape wheel on the shaft to drive the main shaft through the spring shown. The large diameter section is the bearing surface for the single sprag which is held by a short steel pillar with a flat on the side (see pictures below); the sprag is the small cylinder which rolls between the two. The flat angles toward the large diameter section so the small cylinder sits between them; when the arbor rotates clockwise it lifts the sprag upward slightly so it rotates in place with little drag. When the arbor attempts to rotate counterclockwise the sprag wedges between the flat and the large diameter section, preventing reverse movement and allowing winding. (Both the sprag and the large diameter section were rolled on a fine file to add a little texture for improved traction.) A ratchet and pawl used in this type of application is often called a click; this sprag clutch is... a clickless click ;-) I added a retaining clip (not shown) over the sprag because it falls out when the clock is laid flat to work on it. Update: The sprag became unreliable after 5 months, occasionally failing to prevent indexing of the escape during winding. Examination showed the roughness from rolling the mild steel sprag on a file had worn away. I turned a new sprag from drill rod, knurled with a fine straight knurl, and hardened. If this wears then the steel pillar holding the sprag will be replaced with a brass pillar.[25.01.2020 21:44:25]

Gearless Clock

My design hides the maintaining spring, unlike Dr. Woodward's where all of his works, including the maintaining works, are visible. John Wilding used a manually activated maintaining work while I prefer automatic. My notion is that this maintaining work fits well with the simplicity of Dr. Woodward's clock... this from an engineer who got a D in Art Appreciation :-) In retrospect, a maintaining work is a complication to the elegant simplicity of this clock. Impulse occurs only once per minute so it is possible, via observation of the count wheel, to see when the impulse will occur and avoid winding during that time. It is easy to hold the pin wheel against the escape with a finger while winding. Winding takes about 35 seconds with my clock for a run of 5.5+ days. Update2: (January 2014), I found that my maintaining work can cause the clock rate to vary several seconds per day so I removed the sprag and simply hold the pin wheel while winding the clock.[25.01.2020 21:44:25]

Gearless Clock

Update3: (April 2014), Replaced the maintaining work with a "winding aid" . This winding aid prevents the escape from activating while winding, as it would when the weight is lifted. The winding aid requires the user avoid lifting the drive weight when the impulse is about to occur - this is easily judged by noting the position of the deep notch in the count wheel. The winding aid applies pressure to the pin wheel when the string goes slack as the drive weight is lifted. Unfortunately, the winding aid adds some visual clutter to the simplicity of the works. It is less intrusive than it appears in the picture at right because it is partly hidden behind the dial and the case (which were removed for the picture). There is a 3 turn torsion spring (0.017" wire) between the part that holds the arms and the knurled washer; the knurled washer is turned CCW until the arm nears the pin prior to the pin the arm will contact. Then the screw is tightened to lock the knurled washer in place.

Weights and Drive String The weights suggested by John Wilding are about right for my clock when adjusted for my pulley setup. I used 3 lines to the moving sheave to reduce the weight's travel to 1/3. All the pulleys have shielded ball bearings. The jockey weight is 1 pound so the force is 1/3 pound. The drive weight is 1.5 pounds (for force, subtract the jockey force) with a payout of about 19 inches per day or about 22.3 inch-pounds net per day, about normal for a regulator clock. The drive force is about 4.5 times the jockey force - the jockey weight might be decreased by experimenting but is acceptable as is and provides a margin for change over time. I tried several diameters of mono-filament fish[25.01.2020 21:44:25]

Gearless Clock

line as well as a braided fish line but the light line slipped through the drive pulley unless the ratio of jockey weight to drive weight was increased dramatically. Heavy mono-filament (60 pound test) didn't slip but held so well that it wasn't possible for the jockey weight to do its job. The pink nylon string is 62 thou diameter and far stronger than necessary. Braided or monofilament rather than twisted line is required because twisted line causes the three lines to the weights to twist together. I found #18 braided builders line by Starrett at Sears. It was available in bright yellow or garish pink; these colors are deliberately bright for visibility at job sites but the yellow goes reasonably well with brass, see picture at right. This line is flat rather than round but grips well in the drive pulley. The picture shows my classy test weight (would go well with the pink string :), a peanut butter jar containing 4.6 pounds of steel. Both the drive and jockey weights have a moving sheave with 3 lines; fall is about 6.5 inches per day. A drive weight has since been turned from the same steel round which supplied the pendulum. The pulley holders on the weights are 1/2" steel round; the pulleys are smaller than the more traditional ones used by John Wilding, closer to those used by Dr. Woodward. I didn't think through machining of my design very well: the slot to hold the pulley is 0.200 wide and 1.44 long. The only slitting saw I have with appropriate diameter is 3/64" thick so it took 4 passes at 10 minutes per to make each slot. I expected to use mono-filament for the drive line so didn't cut the pulleys very deep. The pulleys worked fine with mono-filament or the round (pink) string but the flat yellow string ran off the pulleys so I made a mandrel to hold them and re-cut them deeper. The blue tape above the pendulum holds a reflector for use with the Clock Watcher's optical sensor.[25.01.2020 21:44:25]

Gearless Clock

Clock Watcher I used the Clock Watcher's setup mode (displays pendulum period in microseconds) to quickly tweak the rate within a couple minutes per day using shims under the pendulum. The original Clock Watcher software was written for my earlier (unsuccessful) clock which had a 1 second pendulum. I took advantage of that one second pendulum to simplify the software and this came back to bite me -- I had to change it to handle this clock's 1.25 second pendulum. Fortunately, it was easy to revise the program so pendulum period is a parameter - the Watcher's display is affected in that it updates on each pendulum swing so every fourth swing it updates by two seconds. I synchronize the Watcher's display with the radio controlled clock, then the gearless clock's hands are set to the minute and the seconds are synchronized by lifting the count wheel backstop to stop the count wheel without affecting the pendulum. When everything is sync'ed I watch either the Watcher or radio clock's display and listen for the gearless escape to trigger on the minute, this sound makes it easy to get everything set properly. I've run this clock with the Watcher for a some time now and it seems reasonably stable, the rate rambles up to +/- 2 seconds per day. Not clear yet what the daily average will be since I'm still working on the clock. The pendulum isn't in final form (I'm still fiddling with temperature compensation) so this may be affecting stability. There is a 1+ second per day cyclical rate change superimposed where this variation occurs hourly and seems to be from a slight bind in the daisy mechanism; removing the daisy eliminates most of this cyclical variation. Here's an example Watcher chart; the big jump at 11pm is where I added an adjustment weight to the pendulum the day before. In a way, the Clock Watcher provides more information than I wanted to know. The pendulum seems to be disturbed considerably by the large, once per minute, impulse: the impulse cycle is about 70ms shorter and the immediately following cycle is about 12ms longer than the average. Following cycles alternate being longer and shorter than the average much of the time between impulses. It acts as if there is a sub-harmonic[25.01.2020 21:44:25]

Gearless Clock

superimposed on the pendulum's natural frequency, not an obvious operating mode. This is gleaned from observing the Watcher's display of raw data so perhaps it isn't an accurate conclusion and could be a problem in the Watcher software, although it didn't happen with my earlier clock which impulsed on each cycle. Note: my Clock Watcher is cobbled together from parts and a microcomputer board that are not readily available so it isn't easily possible to make a copy. Bryan Mumford produces a commercial clock timer. This might be a software alternative, although I haven't tried it.

Builder Notes Having read Dr. Woodward's "My Own Right Time", I tried to proceed along similar lines in construction, using John Wilding's book for basic information and measurements. This lead to several minor differences between my clock and John Wilding's interpretation of Dr. Woodward's clock. John Wilding has written a number of books on building traditional clocks using traditional techniques so Dr. Woodward's clock was a departure from his previous experience, as it would be for most. You can see this in the way he mounted stops for the counterbalances on sturdy arms. So my version differs from John Wilding's in minor details like this as well as the quite different maintaining work. Lucite was used for the count wheel per Dr. Woodward's original clock. This made it easy to cut the wheel plus it allows adding a seconds indication very simply: numbers on the side of the count wheel. I used a spin indexer with a fly cutter in the mill to make this wheel; since the spin indexer only indexes by degrees, my first count wheel has teeth at 7 and 8 degrees alternately - ratchet wheels are less fussy than gears in this respect (but this does make it more sensitive to maximum pendulum amplitude). There is a caution in Wilding's book about friction if Lucite is used for the count wheel. I did run into a friction issue several months after installing the clock when it became unreliable. I had used 0.025 wire and partially counterbalanced the count wheel pawl to minimize friction; occasionally the friction wasn't enough to move the count wheel backwards to contact the backstop pawl. So I made the backstop pawl wire longer and bent it toward the count wheel so the brass section[25.01.2020 21:44:25]

Gearless Clock

holding the backstop pawl is almost vertical. This reduced the friction of the backstop pawl enough that it ran reliably again. It is better to have the count pawl's weight/friction on the heavy side - when friction is slightly too low the clock can stop randomly (it can run for minutes to days between stops) and it takes a while to figure out what's causing it. I haven't seen any indication of excessive frictional losses from the Lucite count wheel, just this effect of relative friction between count and backstop pawls. An observation on my first count wheel was that the teeth were deeper than necessary. Making the notches only about 25 thou deep with one notch full depth (60 thou, rounded at the bottom) makes adjusting the pawl to catch the deflector much easier. Originally this adjustment had little margin for error. The new wheel looks much different, of course, with just small triangular notches and one large notch. I made a special pin for my spin indexer to handle 1/2 degree increments so this wheel has 7.5 degree spacing between notches. The revised count wheel is shown at right with ink added near the deep notch to emphasize the details. Shown in place here. The original count wheel, with deep notches, is visible in this picture. I press or friction fit most things in this clock. In particular, the arbors were knurled lightly as needed with a fine straight knurl so the 1/8" reamed collets fit but their position on the arbor could be adjusted; this was helpful in getting everything to line up nicely. Using Loctite would have made position adjustments far more difficult. Adjustments were necessary to accommodate my maintaining work - I didn't draw it first, just winged it as I went along. Loctite was used to secure the count pawl because setting the pickup of the deflector was touchy and it kept getting knocked out of kilter during testing; Loctite in this one spot made life easier. The mill's DRO was used to drill the holes in the pin wheel; fairly fast, very accurate and no doubt about the result. Watching it work, I'm glad[25.01.2020 21:44:25]

Gearless Clock

the wheel is accurately made because clearance with the escape in operation is not large. 0.031 music wire was used for the pins in the wheel and for wires on the counterbalanced parts. 0.025 music wire was used for the count and backstop pawls. 0.031 stainless safety wire was used for other wires where ease of forming was helpful; in particular, the stops for the escape and the deflector. These stops were mounted by drilling parallel #60=0.040 holes through the mounting pillars, then making a "staple" from safety wire with one side long to be formed as needed for the stop. These staples were pressed into the parallel holes where the slight misalignment inherent holds them firmly in place; the wire is bent as required for the stop. Note that the mounting pillars were first put in place and marked so the staple holes are approximately in line with the expected stop position; these stops are visible in this picture but are obvious only if you're looking for them. Adjusting these stops is done with finger pressure since this wire is fairly soft. Pillars were made from recycled line printer shafts; I didn't use brass or cut the tapers specified --this makes it easy to install and remove them using a drill chuck as a grip. The pillar for the pulley on the jockey weight side of the drive wheel is 0.2" longer and the pillar on the drive weight side is 0.1" shorter than called for in John Wilding's plans. This was done to reduce friction between the lines at the crossing point; not clear whether it is helpful but it seemed like a good idea at the time. I tried the line run so friction is increased and the clock stopped so this seems to help a bit. The mill's DRO also simplified making the daisy wheel. I programmed the DRO for 22 bolt holes and set the diameter for the bottom of the V between petals, then drilled the even numbered 11 bolt holes with a #56=0.046 bit. I then set the diameter for the center of the petals and spotted the odd numbered 11 holes. These spots were used when scribing the petals prior to nibbling and then filing the daisy to shape. The pin wheel center and 4 holes were also spotted and drilled with the DRO's bolt circle function and their accurate location was helpful in fitting the cam and then final fitting of the daisy. (I have since gotten a jewelers[25.01.2020 21:44:25]

Gearless Clock

saw which would have made things much easier.)

Setting Up and Getting it Running It's been more of a challenge to make this clock run well than I anticipated, partly because I'd like it to be somewhat temperature compensated. Initially it clearly wanted to run and when installed it ran well for quite a while... and then it stopped. I'm still learning but it's making more sense as time goes on. I made a number of changes to John Wilding's version but I don't think those changes have caused the issues I've run into. My initial changes were to eliminate fixing screws for wire parts and to minimize "clutter" from excess parts, mainly based on a different feel for how the clock should look. I've continued to fiddle with various aspects over time and added some minor refinements which seem to make it more reliable. In this section I'll cover some details that I think have improved the clock's ease of adjustment, reliability or time keeping. Plus some thoughts on how to adjust it. The adjustments interact so I may not have all the interactions covered... but I'm doing better than when I started ;-) . Two interacting systems form the oscillator: the count wheel and the hook+escapement; they connect via the deflector. I haven't adjusted the deflector other than its stop, i.e. the wires haven't been bent since construction. Update: added the deflector coil spring which was a MAJOR improvement. My approach is to set the impulse pawl up carefully so it takes little movement of the deflector to hook a pin. The pin it hooks must be positioned so that once hooked it releases the escape, the impulse is delivered to the pendulum, and the pawl releases from the pin. The deflector's timing is set by it's relation to the count pawl as the pawl drops into the deep tooth - which is set by the lengths of the count and backstop pawls. To get this all adjusted I work back from the impulse pawl to the count pawl. The impulse pawl (or hook as I often call it) is less critical to adjust if the tip is ground away so the tip is flattened on the outside of the curve. It should be positioned so its closest approach to a pin (as the pendulum swings) is about 5 thou. The pin wheel diameter could be slightly eccentric so look for the closest pin when setting this. Move it up or down[25.01.2020 21:44:25]

Gearless Clock

on the pendulum rod or bend the pawl wire to set the clearance. Then set the deflector stop so the deflector clears the impulse pawl by 5-10 thou. With the pendulum at rest, set the escape so the tip of the hook is about mid-way between pins or up to one wire diameter to the right. The tip of the deflector wire, which will be caught by the count pawl at the deep tooth, should be nearly above the count wheel arbor and about one wire diameter below the wheel's outside diameter (assuming a wheel with shallow notches as described above). Bend the wire as necessary to position the tip appropriately. This completes setting up the escape+deflector so the escape will activate properly when the count pawl pulls the deflector's "trigger". The hex nuts used to hold the clamping bracket for the pendulum spring were replaced with knurled brass nuts to make this easier to adjust. The gathering pawl was shaped differently to make its length easier to adjust - more on this below. The count wheel was replaced with one that has shallow notches rather than full depth teeth (covered above) except for one deep tooth. The backstop pawl was fit into its brass holder, secured by adding a slight bend - a crink - near the end to increase friction; this allows changing the length of the backstop pawl by sliding it in or out of its mounting hole. There are three requirements to the count wheel setup so there are three adjustments, two of which interact. The simple, non-interacting adjustment is the angle of the count pawl section which rests on the count wheel -- this must be set so the wire clears the tip of the deflector wire when it is in the shallow teeth and must catch the deflector wire to trigger the escapement when in the deep tooth. The revised count wheel makes this adjustment easy because the wire drops considerably at the deep tooth.[25.01.2020 21:44:25]

Gearless Clock

The other two adjustments are the length of the count pawl and the position of the backstop pawl. To adjust the length of the count pawl the wire is bent at the bend points, keeping the straight sections straight. This allows adjusting the distance between the pivot and the straight section that contacts the count wheel. The backstop pawl is set so that the count pawl, with the pendulum at rest, is at the center of the slanted part on the deep tooth. The trick here is that the count pawl must also catch the deflector as it slides down the deep tooth and pulls the tooth toward the pendulum. This typically requires adjusting the length of the count pawl to set its position relative to the deflector wire, then adjusting the backstop pawl's position so the count pawl is at the middle of the deep tooth with the wheel against the backstop pawl. It takes some time and multiple iterations to get this right but it is key to reliable operation. The revised backstop support simplifies positioning the backstop pawl. When set properly, as the pendulum is moved slowly left the escape will trigger at about the same distance from center that the hook will release when the pendulum is moved slowly to the right. While the pendulum's horizontal position adjustment can be used to make minor tweaks to the position of the count pawl vs the center of the deep tooth, realize this also affects the hook position vs the pins. Click on the thumbnail at right to see some details. Making the above adjustments can affect efficiency, causing the pendulum swing to increase. If this happens the drive weight must be decreased, either directly or (my choice) by increasing the jockey weight. This happened when I finally figured the above out - the pendulum rod would hit the case for a swing or two following an impulse. Adding a couple ounces to the jockey weight brought the swing back into the normal range. When bending wire, some residual stress is left in the wire. A relatively mild force in the direction that would restore the wire's former shape can[25.01.2020 21:44:25]

Gearless Clock

cause it to move part way back toward the former shape. When bending the count pawl to position it properly it is best to over bend slightly then press in the other direction moderately to get the desired shape and relieve the internal stresses.

Which brings up my concept of how this escape action works. When the count pawl triggers the escape, the action completes in about half a second - too fast for my eye to follow. In thinking about the action, it seems the deflector pushes the hook down and the hook then makes contact with a pin. At this point, friction between the pin and hook makes it difficult for the deflector to continue pushing the hook down. This increasing resistance of the deflector is passed to the count pawl; the pendulum resists this so the count pawl may flex slightly to allow the pendulum to complete its swing. This force from the count pawl curtails the pendulum swing slightly, affecting release of the escape. Of course, the hook is also slowing the pendulum simultaneously, so there's a lot going on in that half second. I added some coils to the upper deflector wire to limit the force it can transmit to the count pawl as well as limiting the force to the pendulum via the count pawl. The force required to move the count wheel is miniscule and the force to move the deflector is tiny too -- right up until the hook catches a pin... In December of 2013 I changed the deflector wire to include a coil spring as noted above, see the picture (click to enlarge). This makes setup much less fussy possibly because the pendulum swing vs hook engage need not be set as precisely. The spring is from 0.020" wire, 10 turns spaced about one wire diameter apart. The start and stop points are approximately aligned so the bottom projection (1/4" long) is in line with the top projection. Upper projection length is 0.9" on my spring. A 0.024" drill was used to make a hole next to the original hole. The bottom spring projection's end was chamfered on fine carbide paper, then a fine copper wire (0.010") was inserted in the hole and the spring's bottom end was forced in. The copper wire provides enough friction to retain the spring and allows it to[25.01.2020 21:44:25]

Gearless Clock

be rotated - the top and bottom projections don't align precisely so rotating allows fine adjustment of the tip's position (bend for coarse position). I made the spring slightly longer than needed and marked it with ink, then ground it to length. This required taking the clock's upper end apart a couple times to get the length within range to allow adjusting pickup by the count pawl via bending the pawl slightly. This spring in combination with the revised count wheel makes getting the clock to run much easier. I noted a groove worn in the deflector wire where it contacts the hook as well as wear on the top of the hook - this spring reduces the pressure applied considerably so further wear should be much reduced. In

January 2014 I replaced the backstop pawl. The new backstop support is an interference fit on the pillar to allow adjusting the backstop position by simply rotating the support slightly around the pillar; this simplifies setup considerably. Note that the backstop is longer so it rotates through a smaller angle when moving between count wheel teeth. This design makes it easier to remove and replace the bridge because only one shaft need be manipulated rather than two. With this design the backstop pawl can be flipped over out of the way when removing the bridge, something that was awkward with the original design.

In the past this clock would run for months and then stop; I'd putter around trying various things and it would run again - but I was seldom certain what change got it going (other than the issue in August 2012 with graphite). I suspect that some of the adjustments outlined here were near their limits and would occasionally drift enough to cause the clock to stop. I won't be certain for a year or so but have noted that it now[25.01.2020 21:44:25]

Gearless Clock

reliably starts after removal/replacement of the pendulum, something that used to sometimes require tinkering to get it going again.

A Case for My Gearless Clock

I built a practice case for the gearless clock from inexpensive poplar to see if I could do it... my first cabinet making project. It took longer to build the case than the clock because I am low on that learning curve plus I had to make jigs and learn how to make joints with a table saw and router. A friend gave me some walnut for the actual case, once I recover from building this case. My case design has a door to allow setting the time easily. Winding could be done by lifting the weight but I've found it easier to grip the string and use that to lift the weight - better control so the string doesn't get lifted off a pulley. The case bottom is split to allow the pendulum and strings through plus it allows easy removal of the case. There are two pins in the top of the case that engage the plywood back,[25.01.2020 21:44:25]

Gearless Clock

so the case simply lifts off. The sides of the case have windows to allow viewing since I expect the works will be of interest to visitors. The clock is mounted on an outside wall (not the best situation) so I used spacers to hold it 1/8" from the wall to reduce heat transfer.

Time Keeping The gearless clock is a novelty clock so time keeping wasn't expected to be precise; the accuracy achieved is surprising. It was not reliable or particularly accurate initially. Changing the pendulum rod from fiberglass to carbon fiber was a big help. It also took a while to understand how to adjust this clock to run reliably. Once it ran reliably and temperature sensitivity was reduced it became much easier to isolate other issues. Changing the deflector to include a spring in the wire in combination with revising the backstop made it much easier to adjust. Once this was done the rate was more stable and I became suspicious of the maintaining work -- removing the sprag improved rate stability considerably. In February 2014 time was accurate within 2 seconds all month - however, it varies when there are large temperature swings outside which can cause a change of up to 2 seconds in one day. It needs a little more work on temperature compensation, I suspect I was lucky that the temperature swings balanced but it now exceeds the accuracy I expected. However, it took me over 3 years of intermittent tweaking to get to this - I hope the info here helps others achieve accurate, reliable operation more quickly than I did.

Further Adventures In building this clock, I set the pendulum horizontal position to the center of its adjustment range and adjusted the drive weight and escape timing so the hook moved the distance between two pins plus 1/2 this distance on either side of the two pins per Wilding's instruction. I set the deflector wire that the count pawl catches very close to directly above the count wheel shaft so it would move as far as possible when it drops into the deep tooth. The backstop pawl length was tweaked so the count pawl was at mid-tooth when the pendulum was still. There are 8 teeth between my count and backstop pawls vs 10 teeth in Wilding's picture. My clock ran[25.01.2020 21:44:25]

Gearless Clock

fine with these default settings so things were left this way without experimenting with pendulum position and its effect on operation. The gearless clock in its practice case was installed on 29 June 2010 and ran reasonably well but slowly accelerated with the rate increasing 1 or 2 seconds per day each week, where this effect was slowly getting smaller as weeks went by. On 20 September 2010 the clock stopped unexpectedly and refused to run for more than a few hours at a time. I puttered around with it improving minor items with the hope it would come back to life but the only thing that helped was adding 4 ounces to the drive weight. Eventually I tried moving the pendulum horizontal position slightly and found this has a large effect on impulse efficiency as judged by pendulum swing. It took some back and forth between the pendulum position, escape timing, and deflector vs count pawl but I was able to get the clock running nicely again. I had set the drive weight with the original setup and now found I could increase or decrease the impulse delivered to the pendulum considerably by fiddling with these adjustments - not what I expected, I thought it was set for maximum efficiency initially. Escape timing also affects efficiency but is not as sensitive as pendulum position. I included a hole threaded 10-32 in the bottom of the drive and jockey weights to allow adding weight for testing and these were helpful in evaluating this issue. The end of the pendulum hook is brightly polished from contact with the pins in the wheel. The clock is back to running with the original drive weight and I'm back to adjusting the rate. Setting the rate with little weights on top of the pendulum has turned out to be an excellent way to make small rate adjustments. With a little luck the slow rate acceleration I observed is gone thanks to this slightly different setup of the basic adjustments. Update: the rate seems much more stable although the clock stopped when the daisy locked up on 1 October 2010. It isn't convenient to attach the Watcher since mounting the clock in our living room so it takes a while to tweak the rate. I am currently chasing a second or so per day -it may be much more accurate than I expected, assuming it doesn't start accelerating again ;-)[25.01.2020 21:44:25]

Gearless Clock

Week ending 17 October 2010: Clock gained 1 second this week. However, it seems to gain or lose up to a second per day - hard to say exactly. No sign of the earlier acceleration, at least so far. March 2011: The yellow line began slipping through the drive pulley causing the weight to descend in a few hours. The yellow #18 drive line was replaced with a thicker #24 braided white line containing one black strand. This doesn't slip but winding makes me dizzy with all the black spots whizzing by :-) I also tried twisted (not braided) line but this spins the weights, winding the 3 lines into one. The hardware store people didn't know what the size numbers mean but #18 is, by eye, smaller than #24. June 2011: Lengthened the backstop pawl to reduce its contact friction with the count wheel. This fixed an intermittent reliability problem. More info here. Rate is within 1 second per day. June 2012: Temperature swings this summer made it obvious the pendulum was under-compensated for temperature. The original compensation was via aluminum tubing extending upward from a stop on the pendulum rod to the center of the pendulum. Length of the aluminum tube was a wild guess. The temperature excursions and resulting rate excursions allowed refining that guess and as luck would have it, the extra length of pendulum rod I left below the stop was enough to allow the extra length of aluminum tube to improve compensation. I added a bit over an inch of tube and tweaked the length (2.8 seconds per thou) to tune it so the clock ran slow by about 4 seconds per day, then added weights on the top of the pendulum to speed it up. This is a surprisingly precise way to adjust rate, much better than a rating nut since rate can be adjusted without stopping the clock and it allows very fine adjustments. I'd been chasing the rate around for over a year and it always seemed to be off by a second or two per day, probably because of the temperature sensitivity. Temperature has continued varying by up to 20F daily but the clock is within a second over the last 5 days which is better than I've managed previously - with luck it will remain stable over extended periods now. August 2012: The clock stopped in a new way - the escape was against a[25.01.2020 21:44:25]

Gearless Clock

pin, so it had not re-cocked itself. I hadn't seen this previously and didn't immediately deduce the cause so I restarted it and it ran for less than a day and stopped again. This time I noticed that the hook on the pendulum was sticking such that it didn't pop all the way up. I had used graphite on the shaft and this had packed itself into a lump in the pivot hole. I cleaned this out with a toothpick and normal running was restored. However, a couple days later the clock began gaining a minute randomly several times per day. This was traced to the deflector sticking, similar to the hook. Again, cleaning a lump of graphite out of the pivot hole restored operation. Best guess is that the exceptional humidity this August caused the graphite to clump up. While some graphite remains, it hasn't caused further problems. Oil isn't generally used in areas which pivot through small angles so I figured graphite would avoid the problem of oil drying up and preventing normal movement. Perhaps I used too much, it is difficult to control application of graphite from the squeeze bottle used to put it on automotive speedometer cables. Rate is back within a second per day. December 2012: Replaced the fiberglass pendulum rod with a carbon fiber rod from the hobby shop. Carbon fiber's temperature coefficient can be set by adjusting the way the fibers are laid up so it was unclear whether this will be an improvement over the fiberglass rod. The aluminum tube used for temperature compensation helped a lot on daily rate variation but the change in temperature due to seasons causes a rate change of over 4 seconds per day. As part of this exercise I changed the hex nuts which set pendulum horizontal position to knurled brass nuts; makes it easier to adjust and looks better too. The sprag in the maintaining work has made marks on the large diameter section, one for each minute since it activates at each impulse. January 2013: Made a new count wheel with smaller notches (described above), reduced the counter-balance weight on the pendulum pawl to make the CW movement due to friction more positive, and enlarged the holes for the backstop pawl's pivots to reduce friction. Coupled with adjusting the pendulum horizontal position this made the clock more efficient. I removed the extra drive weight added some time ago for testing but the pendulum swing was still too large, causing the rod to strike the case - so, I added 2 ounces to the jockey weight to get the[25.01.2020 21:44:25]

Gearless Clock

swing angle back to what it was originally. The carbon fiber pendulum rod has improved temperature stability such that there is no measurable change over night when our setback thermostat reduces temperature. Rate seems more stable than it was, now < 1 second per day and more predictable than it had been previously. When the seasons change I'll get a better feel for temperature stability. February 2013: The clock gained 2 seconds between 13 and 24 February, then between 24-26 February it lost 1 second (likely due to a warm spell). The rate seems more stable than it was with the fiberglass pendulum rod. Apparently even with the carbon fiber pendulum rod it has a positive temperature coefficient, so I'll remove the steel tip I put on the pendulum rod and pin it in the brass pendulum mounting block. Promotes real respect for John Harrison temperature compensating his clocks - I doubt I'd have the patience without the radio controlled clock to provide feedback. March 2013: Removed the steel tip from the top of the pendulum rod and used a pin to capture the upper end of the carbon fiber rod in the brass piece. Shimmed the pendulum for this new setup so it runs about 1 second per day slow and added weights on top of the pendulum to set the rate more precisely. It is now easy to get the rate within 2 seconds per week which is in the range of variations due to atmospheric pressure. Of course, the dial and case remain to be completed but the works are about done, finally. December 2013: The string began slipping again. Rather than replace it I rubbed a small amount of pitch from a white spruce tree along the length of string with the idea it would increase friction (like rosin). This dried in a day or so, is invisible and eliminated slippage. Don't know how long it will last, of course. While dealing with this I noted a small, slightly rusty looking area on the top of the hook where the deflector contacts. A groove is worn in the deflector at the contact point so I added a spring to the deflector. January 2014: Revised the backstop pawl and its support to simplify setup. March 2014: In mid January I noted the pendulum swing varied causing[25.01.2020 21:44:25]

Gearless Clock

circular error. I tried removing the sprag since the maintaining work is activated at each impulse so any difference in how the sprag locked would affect the impulse. This reduced the rate variation considerably. I adjusted the pendulum shim and added weights on top of the pendulum to fine tune the rate; on 1 February the time was 2 seconds slow. I made no further changes during February and on February 28 the time was exact according to the radio clock. While the time varied during the month, it remained within 2 seconds of the radio clock throughout. It is affected by outside air temperature because room temperature varies at night when our setback thermostat allows temperature to drop as low as 55F (depending on outside temperature). Hard to say whether this stability is just luck but it is far and away the best the clock has done up to this time. I suspect temperature is not well compensated but need warmer weather to be certain. Note: I found a problem with my La Crosse radio clock - fortunately, it has only a minor effect on the gearless clock's calibration, about 1/2 second per week. August 2014: I set the clock in mid June and as of mid August it is 9 seconds fast, i.e. it gained about 1 second per week during this period. The weather has been cooler and more stable than usual this summer so the rate change between spring and summer was clear - the clock is over compensated for temperature so I need to remove some of the aluminum compensating tube supporting the pendulum. October 2014: I set the clock in mid June and as of mid October it was 1 minute and 4 seconds fast. A warm spell in late August and early September seemed to cause this, again the over compensation of temperature. The heat is on occasionally now so rate varies randomly again, as it did last winter. June 2015: Over the winter I purchased (eBay) and installed a chapter ring. The chapter ring is supported by springs so bumping it accidentally won't damage it or the clock; it is easily removed by loosening one thumbscrew. The clock stopped mysteriously and this was traced to a spot on the drive string that had too much pitch on it causing it to stick as it passed the drive pulley. Bending the line back and forth at this spot a few times cured the problem (the dried pitch came out as powder). While[25.01.2020 21:44:25]

Gearless Clock

the furnace was on the clock ran slow by varying amounts, 10 to 15 seconds per week; a small weight on top of the pendulum removed much of this. Now that summer is starting the weight has been removed and it is 2 to 4 seconds slow per week, so it remains slightly sensitive to temperature (mainly due to lack of ambition on my part). February 2017: The string began slipping again, requiring winding every 3 days. A little resin rubbed on the string fixed this, just like in December 2013. So it looks like this is needed every 3 years or so. March 2017: The clock began losing up to 5 minutes per day. I noted that the count wheel didn't always move backwards to contact the backstop pawl and that this would sometimes cause it to miss advancing by a second. This apparently happened many times per day. I added a tiny weight to the count pawl to increase its friction with the count wheel to overcome the minute friction of the backstop pawl resting on the count wheel to cure the problem. It gained 1 second over the following week so it's back to normal. January 2018: The clock stopped - which wasn't really a surprise. I had noted in December that the escapement sound had changed such that the release didn't make a positive click although the click as it locked was normal. It seems I had used graphite on the escape pivot and it apparently clumped up similar to the August 2012 incident with the hook pivot. Cleaning the graphite off of things restored normal operation. February 2019: The string began slipping again so I rubbed a little resin on it to correct the problem. Apparently, winding this clock - done by gripping the string to lift the drive weight - slowly removes the resin so this will be needed every couple years. Currently gaining about 4 seconds per week. If you have a comment on my site or its contents, click here scroll down and click again.

This page was last modified 07/03/52037 18:00:09[25.01.2020 21:44:25]

Gearless Clock[25.01.2020 21:44:25]