More trouble - this time a failure of printed plastic.  Latest pic of escapement.  The anchor has suffered from "plastic creep"  and straightened out a bit.  The RH pallet is now catching again!!!  OK I can redesign the anchor with wider arms but not sure that will cure it.

I'm beginning to think I am fighting a lost cause in trying to 3D print a pendulum clock!!   Or at least with this sort of escapement.

The Gravity Escapement is beginning to look more attractive!!

Think I'll do some calculations :-

• escape "wheel" turns in 6s
• stepper motor - 200 steps per rev
• rotation time 200s, 100s, 50s, 25s etc. with various powers of 2
• escape pinion with 12t - gear 50t gives 25s
• or maybe 12:75 giving 37.5s
• timing pulleys of 90t and 60t gives 3:2 ratio which would give 25s at the motor - 8 steps/sec

Now to drive the centre wheel :-

• rotation time of first gear is 37.5s
• rotation time of centre wheel is 3600s giving an overall ratio of 96
• first gear is turning clockwise so a 2 stage spur gear reduction could be used
• or a single stage epicyclic gear set with 95 and 96 teeth.

That is only one aspect of it!!  How to arrange the parts for a gravity escapement is causing considerable headaches!!

I'm thinking of giving the deadbeat escapement yet another go.  The anchor could be reinforced with a backing plate.  Preferably a different colour so that the pallets show nicely.  I'm also considering different shaped teeth on the escape wheel with a flat top rather than a point. I don't think that would affect how it works but may make for a more accurate print.

Modified escape wheel.  Pointed teeth widened with flat ends.

Test anchor design.  Reinforcing plate built in just to see it the principle will work.

20 hours ago, Gina said:

More trouble - this time a failure of printed plastic.  Latest pic of escapement.  The anchor has suffered from "plastic creep"  and straightened out a bit.  The RH pallet is now catching again!!!  OK I can redesign the anchor with wider arms but not sure that will cure it.

I would try filleting the inside sharp corners at either side and make the top part larger for increased stability.

Just seen reinforcing plate idea...

Yes, I think that could be one problem solved but I have another - the escape wheel.

Measuring the new escape wheel.  This shows a clear mm difference in the radius of the teeth!!!  I'm at a loss at to how this can happen.

Been doing a lot of testing trying to find out where this error is coming from and I thing it's poorly defined centre hole.  I'm trying a 5mm hole rather than 3mm to see if this helps.  A disc printed with a 5mm hole measures up as correct!

Failing that I have come across a different form of gravity escapement with 30 "legs" instead of 3 :-
https://mb.nawcc.org/threads/30-legged-gravity-escape-clock.148968/

This uses the gravity escape principle without the extra 10:1 gearing needed for the 3 legged version.  I quite like the idea of a sweep seconds hand of his design but whether I would go for that I don't know.

Been doing some testing on my clock.  With the pendulum on its own without the crutch and anchor system attached it will continue swinging for something like 10m before the swing is down to half.  There is far too much friction in the anchor bearings even though these are ball bearings.  With the anchor system attached it halves in about 10s!!   The gravity escapement has a free swinging pendulum over most of its swing rather than being driven all the time.

Another difference of this 30 legged version is that the pendulum support of well above the escape wheel.  This would suit my clock.

With the pendulum free swinging, I was able to time 60 swings against the sweep seconds hand on my giant wall clock.  I got 56s so 4s in 60s too fast.  Distance from suspension to centre of bob is 105cm.  I guess the rod is making the CofG higher.  Maybe I want a heavier bob.  As it is I would want to increase the rod length by 4x105/60 = 7cm.

I think I shall do some experiments with the 30-legged gravity escapement.  The first will have to be CAD based.  I think there could be a problem with the number of "levels" involved but have to see.

The escape wheel, legs and pendulum rod could occupy the same space if this were deep enough.  This means the escape wheel would be behind the back plate.  Currently the gap between the back plate and the case is 35mm but could be increased and I think it would need to be.

The next point is that it looks like the escape wheel would have to be situated in the centre of the clock rather than offset and this is what the author of the article has done.  This changes how I could arrange the gears.  I think the escape wheel would have to be on a concentric arbour system as he has used.  The pinion for the escape wheel could be attached to it as now, increasing the space required even more.  It does mean the intermediate gears can go off-centre though.

The gear that mates with the escape pinion would have to be behind the back plate and connect with its pinion by a shaft through the back plate.  This latter pinion would mesh with the center wheel (minute wheel).  The rest of the going train could be similar to the present design.

Drive from the weight and timing belt could be applied to the seconds to minutes intermediate gear as now but would probably need a shaft through the back plate.

I have used 3 concentric arbours before - in my Moon Dial Clock.

I think this is beginning to look feasible.  For testing a working model, when I get that far I think I shall use a simple weight with a string on a drum.

The escape wheel will look similar to the deadbeat wheel except that the locking side would be radial rather than at an angle and there will also be pins that will drive the legs outwards.

One version of the escape wheel.  The pins would have to be on a separate part.

Alternatively, the pinion could be separate - indeed even on the other side of the panel.

The arbours, one inside another could look like this for the seconds and minutes with the hours on the outside of the minutes tube.  The seconds arbour/shaft being stainless steel and the minutes being printed PLA.

Alternative escape wheel with built-in pinion.

This is assembled onto the arbour.

This is how the escape wheel without pinion would go on the minutes arbour with separate pinion other side of panel (not shown), but this would rely on being able to fix escape wheel and pinion tightly onto the arbour/axle.  Tricky!!

The gearing between escape wheel pinion and centre wheel can't just be the same as before as the distances are wrong.  One gear pair used 80:10 and the other 75:10 with different spacing of the axles.  Now the spacing has to be the same as the arbours are concentric.  This means using a different modulus on one pair.

Gradually designing and adding bits.

Now working on the design of the pallets etc. on the arms (Don't know if this is the right name for these parts but...)

This is the result.

Aarrgghh - got things back to front.  Not to worry - easily fixed!

Error fixed though pallet sizes may not be final.

Changed the arms to take ball bearings and adjusted the dimensions.  Pivots are 150mm above centre of escape wheel (and clock generally).

I think I should start a new Blog for the gravity escapement version of the clock.

@Gina, I have been watching your heroic efforts but do wonder if the physical properties of your material is suitable for a clock escapement. I don't know what they are but I suspect they are quite different from traditional  material (brass ?).

I would worry about Youngs modulus , creep, coefficient  of restitution and coefficient of friction for a start!

Nevertheless I hope you succeed. 

Regards Andrew 

Yes, the material is plastic - PLA in fact.  But I have built two working clocks with this material that have proved very successful.  This current clock is more demanding and I have found the limitations of the material.  This is why I have abandoned the traditional type of escapement for longcase clocks and gone for a much more tolerant type.

One "push pallet" added.