Dark Lady Clock

[Neil WyattModerator @neilwyatt]

Sorry muddling radial and tangential

Neil

[Russell EberhardtParticipant @russelleberhardt48058]

Posted by Neil Wyatt on 27/10/2016 19:33:10:

Sorry muddling radial and tangential

Neil

I do things like that but put it down to age. What's your excuse

Russell.

[John silverParticipant @johnsilver78232]

Interesting contributions chaps

It looks to me that my pallet is incorrect. Although I did cut it as per Brian's dimensions (shown in blue). As I said, I have overlaid what I believe is Brian's pallet taken from a photo.

What I started with, is shown in magenta ie using the dimensions shown in blue – there's quite a difference between the two. There's no way you can get the red pallet from the blue dimensions

BTW the pallet is mild steel and not hardened

[Russell EberhardtParticipant @russelleberhardt48058]

I think your pallet should look more like this:

The angle between the faces is 90°. The radius should be as per the original. Yours was too big and there was more rubbing than necessary. Make it from gauge plate, harden it, polish it, and fix it to a bush with Loctite high strength retainer.

Russell.

[John silverParticipant @johnsilver78232]

OK ..time to start again with both variants The 122deg Brian pallet and Russell's suggested 90deg pallet

[Russell EberhardtParticipant @russelleberhardt48058]

Bon chance!

Russell

[John silverParticipant @johnsilver78232]

Well initial results with Russell’s suggested pallet look promising – certainly a lot easier to make.I noticed that my escapment wheels are not exactly perpendicular to the pallet rest. So i have shimmed the pallet base cross bar at one end i think i will now round and polish the escapement spokes and pallet to reduce any friction

[John silverParticipant @johnsilver78232]

Time for an update

I can't get reliable operation of the clock and found that when it stopped, you could pull the Foliot up and the gear train was stuck!

Investigations found a few issues:-

(1) Main wheel brass bearings were very tight?? I'm sure I reamed these out but had to ream some more.

(2) I looked at the pinions and found that one of the pins was wonky making the spacing to the next pin too large.

Now I had a look through John Wildings Alarm clock which the Dark Lady clock seems to be based on. Interestingly, there is a very detailed diagram explaining who to shape the pallet.

What was also interesting is that although John uses 'bird cage' pinions he did in fact use a commercial involute gear cutter for the main gears.

Checking my first pinion to the main wheel showed that they could be very closely meshed. However on the escape pinion, the wonky pin meant that I had to widen the spacing between the gears leading to excessive backlash – which I believe and hope is the reason why the gear train locks up periodically.

So I am going to machine new pinions and then I will have to re-make and drill the bushes.

When the clock was running it was running quite smoothly and evenly after I rounded all the escape wheel teeth (And polished them) and also ensured that the pallet shape was evenly shaped and polished.

I'm sure I'll get it running but at least I know I don't have to re-make the gear train and Involute gear pattern is fine with 'bird-cage' pinions

Edited By John silver on 08/12/2016 10:22:45

[john carruthersParticipant @johncarruthers46255]

I found a tapered reamer at a boot fair which was perfect for the bearings. I cut them quite slack as the frame moves noticeably when loaded and running.
This week the clock started 'running away' and had to be adjusted by 10minutes in 24 hours.

[John silverParticipant @johnsilver78232]

Well after all my mods ie new pinions, polishing the escapment teeth etc, it will run for a time and then stop. Friction seems to be the issue although lifting the pallet causes the drive train to run freely. So I think the drive train is OK but i might make the bush holes slightly larger. I still think my problem lies with the pallet and escape wheels. I did notice the John Wildings design offered an alternative escape wheel using pivot steel pegs. I think this would work better and eliminate teeth shape and or finish issues?

[Russell EberhardtParticipant @russelleberhardt48058]

Friction is your problem. In an earlier post you said that the pallet is unhardened mild steel – not good for low friction. You could case harden it before polishing but personally I would use gauge plate and fully harden it without tempering. It would then have to be glued to the bush. The working surfaces should be polished to a mirror finish.

Oil – just use the barest amount on each pivot and just a drop from the end of a fine needle on the pallet face. Preferably clock oil but, for that clock, I would think a thin sewing machine oil would do. Don't oil the gear teeth.

Russell.

[Mark BusParticipant @markbus97330]

Hi ,

Look at my thread that I started 1/11/2014 in the the clock forum. I haven't read all of yours just saw the stopping clock video but it looks familiar to my problems.

Mark

[john carruthersParticipant @johncarruthers46255]

You could try increasing the drive weight to get it running then gradually decrease it as things loosen up?

[John silverParticipant @johnsilver78232]

Ok it's been too long but this is where I am at…

At one point I had everything together and the clock would run for a bit and then stop. I found I'd you lifted the pallet, the gear train was stuck and giving the main wheel a jolt caused the weight to fall and the gear train to spin wildly.

I frustration i contacted Brian who was adamant that the problem lay with the teeth style. As a result I bought a cyclical clock tooth cutter and remade the gear train gears.

I was quite disappointed to find there didn't seem much difference only the the gear train seemed to have less rattle. Again I rebuilt the clock (less all the motion works) and again the same problem!! The gear train kept sticking

Now I did notice that one of my pinions didn't have perfect 45degree spacing of the pinion wires and this did cause a slight resistance when turning the wheel and so re-machined it (took a couple of goes to get it near perfect).

So back to the depthing gauge .. First off the main wheel and second wheel pinion. I could get free spinning with the teeth only engaged to a depth of the pinion wire. I have always thought that the pinion wire in a tooth gap should end up about half way. Adjusting the gap between the gears eventually causes the gears to bind/jam and increasing the gap does cause the gears to spin but there is quite a lot of play.

Again, I re-depthed the second wheel to the escape pinion and drilled the bushes to suit. To my utter dismay, I found the Gear train would easily bind and taking account of John C's experience elongated the Bush holes for the escape arbor to allow the bushes and arbor to be moved before bonding with super glue.

Now this time the gears turn really smoothly with hardly any effort on the main wheel and so yet again, fitted everything else. The result exactly as before random no ding of the gear train. What I did notice was that the escape wheel could be turned ever so slightly with the second wheel so I have concluded that the main wheel is binding with the second wheel pinion only when the load of the weight is added..

So where I am now is that I think that the main wheel to second wheel pinion is not meshed enough, it appears that I can reduce the spacing of the wheels by about 0.8 to 1mmm.

The trouble is I'm not sure what the optimum meshing should be I can only increase the meshing on the first two wheels and see if that improves the binding. When the clock was working the pallet/escapment seemed fairly regular so i think that part is OK.

I'm also debating (now i have remade the opinions) whether to go back to the invite gears i made (I noticed the teeth width using the cycloidal cutter is not very even compared to the involute which are spot on.

As i said Brian was adamant about the tooth shape but email communication appears to have stopped?

I am absolutely determined to get this working but there have been quite a few times where i was tempted to give up but i have invested a lot of time and money getting tools and materials and this clock is just a stepping stone for other peojects, so if i can't sort this out then there's little point trying to build anything else

[john carruthersParticipant @johncarruthers46255]

Mine 'stuck' occasionally on one tooth at first but I left it running with a slow drill, (without the escapement) for an hour or so to bed everything in, seems ok now.

Don't get disheartened, leave it for a while, mull it over and come back to it.

Last week I had a completely different problem to yours John; on mine a wheel and pinion was loose on the axle allowing it to creep along, then bind on the wheel below and slow things down. Then it would work along the other way and loosen up, speeding it up. I'd been trying to adjust it for weeks ;-/
Got the little monkey in the end.

Another source of friction was the middle verge support.
When the weight was hung it distorted  the frame slightly and tightened up on the verge. I'd made the upper and middle bearing holes too tight. A tapered broach eased it up enough to run.

I must get a new cord this week too, they soon fray on the spiked wheel.

Edited By john carruthers on 24/04/2017 08:49:20

[John silverParticipant @johnsilver78232]

I like the idea of using a drill what’s frustrating is that the gears turn perfectly with no weight. But as soon as you add the weight it binds after a while. I need to see if its in the same place in the main wheel. I might even try my involute tooth main wheel as the teeth spacing look perfect. For some reason the width of the teeth using the cycloidal cutter are are not very even??

Edited By John silver on 24/04/2017 15:49:09

[john carruthersParticipant @johncarruthers46255]

See if the frame distorts slightly when the weight is hung.It's surprising how rough the teeth can be and still work.

Does it run freely with a no escapement and just a very light weight?

[Martin KyteParticipant @martinkyte99762]

Hi John.

Your problem could well be depthing. You spoke about deeper engagement ? The action should be that the contact between wheel and pinion takes place after the line of centres not before. If to deeply engaged the action tends to be changed to before the line of centres and friction will cause a wedging action where the teeth are driven into closer mesh thereby increasing the friction and so on. Action after the line of centres causes the teeth to disengage and therefor wedging cannot take place. If you suspect you have a locking up issue aim to depth the train less deeply and the problem may well disappear.

regards Martin

[John silverParticipant @johnsilver78232]

Thanks John & Martin for yor thoughts.

In the short term I'm going to re-make my main gear as for some reason the teeth are not even. I think that my home made dividing tool is a bit stiff at certain points and this might cause a bit of slippage?

In any event I bought a new rotary table and the dividing plates i bought for my divider are designed for the rotary table anyway, so I should be able to make it properly this time (oddly all the other wheels appear to have nice even teeth spacing

I just tried gently turning the drive train and most of the time a very little movement on the main wheel cause a little movement on the escape pinion.But in one position moving the main wheel doesn't cause any movement of the escape wheel and there is quite a lot of play on the second wheel pinion. It's as thought the main wheel teeth are banging on the second wheel pinions instead of sliding past and as a result the main wheel wont turn.

I just think that the teeth spacing is an issue and I will need to re-make the main wheel before looking at anything else??

Cheers for now

John

[Martin KyteParticipant @martinkyte99762]

One other good wheeze is to mark the position of each tooth in contact with a fine marker pen when lock up occurs. If it happens consistently at the same position then the wheel in question is easily identified and the tooth can be closely examined.

You seem to have identified a possible issue anyway. However it may pay you to do the above whilst you are cutting your new wheel so you can improve your fault finding. If clocks run right from the start you don't tend to learn much so be encouraged and see this as a bonus.

regards Martin

[John silverParticipant @johnsilver78232]

OK, it's almost there !!

So I decided to ditch my home made dividing tools (using commercial divider plates) and instead use my new HV4 rotary table with the dividing plates I already had. Not wanting to waste any more 3mm blanks I drew out the gear 1:1 on AutoCAD and printed it out. I also checked against a commercial Steel 80T gear I bought (along with a 60T and 32T gear that I was going to make a simple gear replicating jig).

So the gear was cut and this time all teeth perfectly uniform. I still had to re-depth but at least there was more meshing. I re-assembled the gear chain, added the recommended weight and off it went. The clock kept going until the weight reached the floor. I repeated several times and each time the clock ran trouble free. I felt confident to re-fit the motion works and bell ringer.

Now I have noticed a potential meshing problem with the motion works gears. These were cut with the involute cutter but there is slight sticking point which I need to sort out – it's sometimes occurs. The clock will run fairly reliably but still stops every now and then. I have checked to see if the motion works is free to turn which it is, so it might just be the extra friction and I might need a tad more weight to overcome it.

But I feel I am really close to sorting this out. Like John I elongated the brass bearing holes to allow the arbors to be moved slight with respect to each other and then bond in position with superglue. This way I could be sure that the drive train was perfectly free to run

[john carruthersParticipant @johncarruthers46255]

Got it regulated yet John? It takes quite a while to bed in.

I found the large weights with a 0.5mm thread on the foliot too coarse an adjustment.
I got it close, then fitted a couple of extra small fancy nuts at the ends of the foliot for fine adjustment.

[John silverParticipant @johnsilver78232]

Posted by john carruthers on 12/05/2017 18:50:41:

Got it regulated yet John? It takes quite a while to bed in.

I found the large weights with a 0.5mm thread on the foliot too coarse an adjustment.
I got it close, then fitted a couple of extra small fancy nuts at the ends of the foliot for fine adjustment.

Hi John,

Getting there (I think) – I now have it running pretty reliably the clock only stopping when the weight reaches the floor. Although, a couple of times the clock has been running for hours (motion works are now fitted) and it stopped. I think a tiny more weight is needed. Alas both my Antique brass clock weights are 3.2kg (one is very slightly heavier than the other, so I have fitted that instead).

Hopefully, as you say when things bed in a bit all should be fine. Time keeping seems pretty good but I just need to get it running for a few days before there's any point adjusting anything.

So it would appear that the slightly non-uniform teeth on the main wheel was the problem. A commercial rotating table + dividing plates was the answer (I use a commercial MOD1 clock cutter).

I'm not convinced that using the cycloidal cutter made a difference as my motion works were cut using a involute cutter and they turn nice and cleanly

– but I wonder if one introduces more friction than the other??

Next project will be Woodwards gearless clock

All the best

John

[Russell EberhardtParticipant @russelleberhardt48058]

Well done John. It sounds as if you have sorted it

Posted by John silver on 15/05/2017 09:49:38:I'm not convinced that using the cycloidal cutter made a difference as my motion works were cut using a involute cutter and they turn nice and cleanly

– but I wonder if one introduces more friction than the other??

I suspect that the use of cycloidal gears in clocks has more to do with tradition than theory.

Russell

[John silverParticipant @johnsilver78232]

Well clock seems to run most of the day and then stops?? I have added another 450gms of weight to the current 3.2kg and see if that helps?

It may need running in, but I have to stop it each night ,as it annoys my Asperger's son.(luckily he is off to Durham University in October).

I'll refit the bell striker parts later today

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