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Longcase (Grandfather) clock with 3D printed gears etc.


Gina

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Decided to have another go at the deadbeat escapement and see how it goes.

I've printed the deadbeat anchor and the escape wheel and now reassembling the clock, having stripped it down to try the gravity escapement.

681417314_Screenshotfrom2021-01-1819-16-22.thumb.png.66264d8f01ece21eba794ba889b68cc8.png1604862921_Screenshotfrom2021-01-1820-01-00.thumb.png.af63e72d91d1c835620d94a45dc35b4a.png
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  • 2 weeks later...

It's a pretty complicated project to actually get working. I think it relies heavily on the accuracy of your printer, I know you've had problems with the anchor. 

Fingers crossed you get things sorted. ? 

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You're right there Mark 😄  And yes, printer accuracy is a major point!!

 

I have abandoned the standard deadbeat escapement and going for a modified gravity escapement with 30 "legs".  I'm basing my escapement on this 30-legged gravity escapement.

 

Unlike the standard gravity escapement which has a escape wheel which rotates in 6s the 30-legged version takes 60s like most pendulum clocks you might see indoors.  This simplifies the design considerably, saving lots of gears yet the escape mechanism is not really any more complicated.

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A difference from my earlier design with deadbeat escapement is that the escape wheel is in the centre of the clock face.  This means the seconds arbour (horological name for shaft or axle) is concentric with the minutes and hours so will need sleeves.

 

This shows the seconds and minutes arbours as a 5mm SS shaft inside a 3D printed PLA sleeve.  The hour arbour will go on top of the minutes.

1699736164_Screenshotfrom2021-01-3120-46-35.png.e69a9526c92a06fced4c4b401432c6b6.png

 

This results in this assembly.

904439809_Screenshotfrom2021-02-0111-37-28.png.f11aa8f9a97db34d3440098df0384f86.png

Edited by Gina
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Now to the detailed design.  Locking pallets added to arms.  (I don't know if "arms" is the right term, but it makes sense to me 😁).

1248238169_Screenshotfrom2021-02-0110-50-14.png.c70bbddb2e72813926ac64d72e17479e.png

 

Assembly.  This shows the teeth on the escape wheel latching on the pallets.

289579092_Screenshotfrom2021-02-0115-10-10.png.6947eaaed599424edcbf5f7e51c56696.png

 

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Now to the "push pins" and pushing the arms outwards.  A lug on the arm will be pushed outwards when the pendulum swings to the left sufficiently to release the left-hand locking pallet allowing the escape wheel to rotate.

772408689_Screenshotfrom2021-02-0116-06-30.png.ea393b4b101ee0e20c6b100c2f267a6e.png

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That is the escapement I am trying to copy.  In PLA rather than metal.  Tried to put text with the video but couldn't.  Don't know why.

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Rather than adding extra gears I decided to drive the escape wheel directly with the timing belt so added a printed 72t timing pulley to the wheel rather than a spur gear.

40622163_Screenshotfrom2021-02-0211-55-39.png.f135e216570cd38066b8bcc85288e0b9.png

 

646517250_Screenshotfrom2021-02-0211-52-27.thumb.png.176bced44530cff14d68aa585283c7f6.png

 

The spacer moves the belt away from the push pins.

27949217_Screenshotfrom2021-02-0211-54-42.thumb.png.b2ae0679b7ed995f433066f64acb5bec.png

Edited by Gina
Added pic.
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Before going much further with the design I decided to check how the arms would fit on my print bed.  Not a lot of spare space but will fit if rotated.  Design of arms is not finished but sufficient for this check.

 

891901623_Screenshotfrom2021-02-0213-38-29.png.95335349236fcc850ba25d6f4007ac37.png

 

846703050_Screenshotfrom2021-02-0213-39-29.png.fd8fb22424c08f1b43364a56c89ffef4.png

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Had some problems with the centre hole not being perpendicular to the XY plane.  Been doing numerous tests to try to find where the problem is.

 

Firstly my standard orthogonality check on the printer with this test print.  !00mm legs of 10mm x 10mm cross-section.

1536839068_Screenshotfrom2021-02-0310-05-45.png.f35d3e75b42b730d4c242b4675875824.png

 

That proved perfect so problem is not that.

 

Then tried various simplified versions of the escape wheel.

 

Simplest, just a vertical tube with base extensions so I knew which was X and which was Y.

450364703_Screenshotfrom2021-02-0309-53-19.png.52798c9f70901fce9bcd1d21aa2b3cd8.png

 

Then solid wheel with one tooth to show orientation.

1032426304_Screenshotfrom2021-02-0315-56-40.png.fd19b475fb1e9ffd737b16480d736d78.png

 

Finally, the escape wheel without the bulk of the timing pulley.

1458965596_Screenshotfrom2021-02-0318-52-17.png.a38a4107d3cc961847b57304a3d8ce41.png

 

These were alright.  So decided to print the timing pulley as a separate part with suitable sized hole in the centre.  This will then be attached to the escape wheel.

2016695250_Screenshotfrom2021-02-0318-57-32.thumb.png.dd6379da5c7c5902e0d78859413fa967.png

Edited by Gina
Added pic.
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Having had success printing a worm drive for my imaging rig I thought it would be nice to see if I could use one in the clock, reducing the number of gears and producing a neater result.  (But mainly for fun!).

 

To go from seconds to minutes means a ratio of 60:1 so a single start worm and a 60t worm gear is what's wanted.  (Assuming the worm is driven at the same rate as the escape wheel.)

 

To save gears in the vicinity of the escapement and cluttering it up I decided to drive the worm from the timing belt.  Another printed 72t timing pulley running on the timing belt will rotate at the right rate.  So far so good, but the worm shaft will be at right-angles to the shaft of the pulley unless the belt is twisted instead.  This proved impractical so I shall print a pair of bevel gears.

 

321281359_Screenshotfrom2021-02-0421-15-47.thumb.png.9c6c9e72e542f0793b47936368bec08b.png

 

1034874410_Screenshotfrom2021-02-0421-17-18.thumb.png.85f341546bc287c9c7d4f885f929cbad.png

 

 

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The timing belt will go from the timing pulley on the escape wheel down and to the left and over the second 72t timing pulley before going downwards to the pulley attached to a weight.  As with the previous version, the belt will then go back up and over the auto-winding pulley on a stepper motor.  The down again in another loop with pulley and weight to tension the belt and keep it engaged with the timing pulleys.

 

Similar to this test rig but with smaller weights.

Testing03.thumb.JPG.6b7f929af72524cce1b9a97ef50f9b7f.JPG

 

In this new design the timing belt goes over a timing pulley in the centre of the clock face then to the left and down over the second 72t timing pulley.  Then the drive goes through a shaft, a pair of bevel gears and another shaft to the worm.

 

Screenshot from 2021-02-04 22-34-35.png

 

Screenshot from 2021-02-04 22-38-20.png

Edited by Gina
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This shows the run of the timing belt added but I think I might add an idler pulley to increase the wrap round the pulleys, particularly the left-hand one.

 

1172453490_Screenshotfrom2021-02-0423-20-41.thumb.png.fdad998228a869e837bae715ad276d35.png

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Getting close to being able to test the escapement.  Not sure the arms are right but won't know until I try them with the escape wheel.  A couple more parts to design - adjustable stops for the arms.  Will probably need to add weights to the arms too.

 

1801322763_Screenshotfrom2021-02-0520-52-33.thumb.png.50d2fb5a76d443b0f7fa48d7d9ee7d90.png

 

606243790_Screenshotfrom2021-02-0520-50-22.thumb.png.06e3bf7487f0da9904a06ab8b68d1d99.png

Edited by Gina
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14 minutes ago, Stub Mandrel said:

I love this Gina, you break every single rule in the clock book 🙂

 

Rule breaking is what I do best 🤣

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I like to be different.  As one of my friends locally says - I'm "Mad as a box of frogs".  Love that.   Love the "mad professor" hat . 🤣

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Just finished printing the arms and they look alright.  Printed well.  Lots more to design and print before I can test it. 

 

I need a new pendulum suspension bracket as the pendulum is now further from the back mounting plate.  In fact I think I'll attach it to the case to make the pendulum easier to attach when mounting the clock on the case.  Also, have variable stops for the arms to design and print.  Oh yes, plenty to do yet!!

Edited by Gina
Typos
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