Photo of the escapement.  The LH pallet is about to release the tooth on the escape wheel, but the RH pallet is not clear of the corresponding tooth so cannot move into the gap between teeth.  I see no reason why the pallets shouldn't be a bit narrower.  The drive period would be reduced slightly but that's secondary, I think.

Slimmed down pallets.

On 26/01/2021 at 13:50, Gina said:

It's printed well and seems fine - vast improvement!  Didn't realise stale filament could be so troublesome!!!

When I have moved I will get a food drier to use as a filament drier.

Fitted the new anchor and it nearly works.  The corner of the RH pallet Is just catching.  I think I can just take a file to the print and remove a small amount.

That didn't do it and the separation of the pallet lock surfaces are a whole 3mm too far apart as compared with the escape wheel teeth.  I just don't know how this large error could have arisen!!.

That error is too big to be anything other than a calculation or CAD error on my part!!!  I shall go through the design again very carefully, checking every step!

That is wrong.  I think I have a clue what I did wrong due to a brain malfunction!!!

Yep!!  Found it!!!  Try counting the teeth in the escape wheel below.  From lots of coding with binary numbers there are 32 teeth rather than 30!!  DOH!!!

Here's the escape wheel error - 32 rather than 30

Changing that was easy.  Replaced the 32 with 30 and got this new CAD model.  The anchor will be slightly less easy.

Designing the deadbeat anchor.  Green circle defines the locking surfaces.  Black is the tooth point circle.

Clock parts printed.  Made up a test rig with a 3mm hole in a piece of wood and a mark at the escape wheel tooth points.  Then turned the wheel to see any errors in the teeth.  Found a difference of just under a mm so got a file and and filed the high ones down to near the low ones.  Reckon the teeth are now within 2 or 3 tenths of a mm.

Put the clock back together ready for testing again.  Meanwhile, I've been looking on the web for deadbeat escapement design and there seem to be many variations.  Don't suppose there's anyone here who knows anything about this is there???

Been testing and no joy!  The anchor seem about right but now it's as if there's too much friction in the gearing!!!  Yet I haven;t changed anything except the escapement.

After fiddling with the anchor position and the clock angle I got it running in fits and starts.  ie. as before tick tock tick tock where the teeth were a bit higher and skipping where lower.

Looking closely at the anchor, it still isn't right. 

LH Pallet shows the tooth just coming off the locking side of the pallet. 

RH Pallet.  The locking surface on the left should be half way between teeth and the RHS should clear the teeth.  This pallet is wrong.

Pallet should be here - shown in black.

Redesigned the anchor, moving the RH pallet a couple of mm inwards and printed.

Swapped anchors on my clock and the new one is much better.  The clock actually ran for a minute or so.  I think it just needs a bit more drive force now.  Heavier weight for instance.

Maybe I could move the drive (white timing pulley and spur gear) from the blue centre wheel to the next in the train (red) but though the gear ratio between these is 8:1 the red gear is 75t rather than 80t so not actually 8x.  This means a re-calculation of the motor speed and ratios needed to obtain a sensible stepping rate.

Drive calculations :-

• If I drive the red gear, it's the same as driving the pinion on the escape wheel (except for the direction). 
• The escape wheel rotates once a minute and the pinion has 10 teeth.
• A 50t gear on the large timing pulley would rotate with a period on 5x60=300s
• Stepper motor takes 200 steps per rev.
• Stepper motor takes 200s at pulse rate of 1Hz
• A timing pulley ratio of 3:1 gives 100s
• 90t and 60t would give 200s for motor rotation and one step per second.  Ideal!

Practical considerations showed 50t gear would be too big so going for 25t and stepping at 2 per second.

1. Printed new 25t gear and attached to 90-t timing pulley. 
2. New drive system installed in clock and clock installed in case ready for testing.
3. Have been testing clock and still no joy - still same problem of running and skipping.

I seem to spend all my time stripping and reassembling my clock, interspersed with thinking, designing and printing new parts.  All the time it's the escapement that's the trouble!!  I guess that's telling me to change the type of escapement...  I dunno...

One thing I've noticed while testing is that the pendulum swing decays very rapidly as if there's a lot of friction.  It seems to be worse than it used to be and I can't think why though I did shorten the suspension spring.  Maybe a different sort of suspension would be better.  eg. knife edge or even tiny ball bearing as in the anchor bearings.

Of course it could be the anchor axle bearings or something else associated with anchor of crutch.  Maybe I'll try the pendulum on its own without the crutch etc.

I had another thought about how a pendulum clock could be driven, as opposed to a weight and chain or belt.  The idea is to allow for the intermittent motion produced by the escapement, and that's a spring.  OK been done before but I don't just mean a mainspring wound by hand but with auto-winding.  As with the weight system and auto-winding the spring could be shortened right down.  The escape wheel could have another wheel on the same axis and drive the escape wheel with a spring.  This wheel would be driven by a stepper motor.  From here the rest of the clock could be driven by spur gears where the pinion drives the larger gear and very high ratios are possible or another arrangement like epicyclic gears or even worm drive.

<Stub is thinking>.......