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Test Jig #3 - Hours & Minutes Clock

by syvwlch, published

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Test Jig #3 - Hours & Minutes Clock by syvwlch May 19, 2011

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Description

This is the current release candidate for the Printable Clock Project. Many thanks to the many Thingiversians who have contributed over the last few weeks!

It is a work in progress and probably will need tweaking to even tick, let alone keep time. It currently has breakage issues in PLA, ABS is recommended.

Test Jig #2 was a major milestone, passing all four tests, featuring in the first video of a ticking printed escapement for this project ( prototribe.net/vidplay/testjig2.html )and serving as a development base for improvements from multiple Makers. If you want to print something that ticks, print Test Jig #2 with all the latest parts.

Test Jig #3 is intended to regroup all that progress into a new base camp for what we hope is the final push: an actual printed clock that keeps time. If you want to spend plastic and time in support of that goal, print Test Jig #3 and share with us what went right and what went wrong.

This current design is based on feedback from early adopters ssd, rustedrobot and TheRuttMeister, and in particular a very clever rustedrobot design for a ratcheting drum that rewinds the clock: thingiverse.com/thing:8555 Special thanks to Renosis for rendering gears 02 thru 07 on his machine last night when mine was not up to the challenge!

I've uploaded a snapshot of the code which generated these parts to this page, but the best place to find the latest and greatest is on github:
github.com/syvwlch/Printable-Clock-Project

Major improvements include: the ratcheting drum, countersunk holes for the frame, a snap-fit extendable pendulum, and an escapement design which should tick as printed (little or no hand-finishing required).

I tried to go for a four gear clock, but getting a 60:1 ratio in two gears is just not practical... the pinions get too small. I also went ahead and added hour and minute hands. I can make alternate parts for a hand-less version if the concentric shafts are too much of a problem.

Recent Comments

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Awesome! Can't wait to see you at the not cave later today. That is a strong foundation to build on. :)

I been printing this out over the last week or so in hopes of making it to the clockathon. Syvwlch, this thing is awesome. Reallly nice work and it gets me super excited about learning openSCAD.

I have a lot of thoughts which I'll share in person later today.
Mostly, I agree with TheRuttmeister about geartrain resistance. I noticed that the resistance seemed manageable from the perspective of the minute hand and could be powered from that gear.

As a test I hung a weight (about 500g) fro
m the minute hand gear and it ticked!! You can view it here: http://www.welovephotobooths.c.... Obviously the pendulum length + weight needs to be adjusted.

I'm very confident that if we attach the drum to the minute hand gear we can get this baby to keep time (but only for a few h
ours before winding the weights). I have many other thoughts as well which I'll share later today.

Thanks!!! This rocks.

Just nobody beat me to a ticking clock!

Grrrrr!!!
&
amp;gt;:o

Makes

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Instructions

Print one of each STL, keeping track of which gear is which. Since this is a six gear clock, it does not have parts 08 and parts 09. Use four M3 bolts, two to hold the frame, and two to serve as shafts.

The gears are numbered from front to back, starting with the drum (01A and 01B) and finishing with the escapement wheel (07). Gears alternate on either shaft, and the pinions (the smaller gear attached to the center of the larger one) face forward.

The pendulum and the escapement are combined in a single print and snap-fit together (a design idea from Aubenc).

Attach a string by the middle to one of the side holes on the drum, with both lengths wrapped around the drum in the same direction. That way, when one length unwinds as the clock runs, the other gets wound up. Attach a weight (100g, perhaps?) to the length which locks the ratchet against the stops (clockwise from front), and a smaller weight (20g?) to the length which unlocks the ratchet in the opposite direction.

Comments

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bfraser on Jan 22, 2012 said:

I been printing this out over the last week or so in hopes of making it to the clockathon. Syvwlch, this thing is awesome. Reallly nice work and it gets me super excited about learning openSCAD.

I have a lot of thoughts which I'll share in person later today.
Mostly, I agree with TheRuttmeister about geartrain resistance. I noticed that the resistance seemed manageable from the perspective of the minute hand and could be powered from that gear.

As a test I hung a weight (about 500g) fro
m the minute hand gear and it ticked!! You can view it here: http://www.welovephotobooths.c.... Obviously the pendulum length + weight needs to be adjusted.

I'm very confident that if we attach the drum to the minute hand gear we can get this baby to keep time (but only for a few h
ours before winding the weights). I have many other thoughts as well which I'll share later today.

Thanks!!! This rocks.

syvwlch on Jan 22, 2012 said:

Awesome! Can't wait to see you at the not cave later today. That is a strong foundation to build on. :)

TheRuttmeister on May 24, 2011 said:

Ok, feedback.

Does not tick. :'(

Way too much resistance from the geartrain. I've hung quite a lot of weight on it and tried to turn it by hand. I can't generate enough torque either way.

Clearances for shafts generally was a little generous. Was a little loose on M3 so I ran a 3.5mm drill through and used so
me 1/8" brass rod.

Clearances for the concentric shafts was perfect.

Detail generally was too fine. Details like the walls of the concentric shafts and the hands print as just walls, no infill. There are advantages, but it does mean that they are very fragile.

I'm also not sure about spacing betw
een the gears. There might be a better way to do it.

rustedrobot on May 24, 2011 said:

Aaarrrggghhhh!!!!

So close! Out of curiosity what were your skeinforge settings related to the width and thickess of the extrusion?

TheRuttmeister on May 24, 2011 said:

Maybe a huge drum would work, with scaled down gears (although I doubt they would be printable on a cupcake). Plus the drum would need to be way bigger than the cupcake build area.

Looks cool though.

TheRuttmeister on May 22, 2011 said:

Finally, ready to start on this. One question, can I reuse any of the bits from test jig #2?

TheRuttmeister on May 22, 2011 said:

I'm guessing no, unless the escapement is the same. Everything else looks different.

crsdfr on May 20, 2011 said:

Fantastic work syvwlch! I'm going to make this with SLS very shortly. I'll try a "pocketwatch" version also.

syvwlch - as as exercise in sheer lunacy, I was wondering whether you'd oblige a request; Ccould you please output these files positioned "as is" from the raw Openscad output? I'd love to attempt to make this clock as a "single part" assembled straight from the machine. I see no reason why it woul
dn't be possible and it would be a fascinating exercise in the limits of Rapid Prototyping.

Again, brilliant stuff, can't wait to see what you come up with next.

syvwlch on May 20, 2011 said:

Thank you :-)

I suppose I could make a variant that imports and positions the existing STLs, with slight mods to the frame and shafts... Trying to render the entire clock directly would probably take hours! It's also going to be a VERY big STL, I would imagine.

Lastly, how big is your printing area, and what k
inda mechanical clearance would you recommend for the gears and for the shafts? Right now, this is sized such that the largest parts barely exceed 80x80x80 mm, the clearance between a shaft and a cylinder able to rotate freely around it is 0.5 mm, and the clearance for a snug snap-fit is 0.25mm. The
clearances may need to be reduced if SLS is much more precise, no?

syvwlch on May 19, 2011 said:

Damn, looks like the dreaded bald gears struck on part # 04.

syvwlch on May 19, 2011 said:

The pinion (small gear) has no teeth, as sometimes happens with the latest version of OpenSCAD and the MCAD library.

Dirty socks and kitten farts, I hate it when that happens!

TheRuttmeister on May 19, 2011 said:

A. Woohoo!

B. Dangit, going to be busy all day today putting an old car back together, no printing till the evening!

C. How thick is the frame? Because its hard to find m3 bolts longer that 50-55mm.

D. Woohoo!

syvwlch on May 19, 2011 said:

A. woot!

B. sweet, sweet anticipation.

C. The frame is significantly thicker. I slimmed down the individual gears a smidge, but there are a lot more of them. See the JPEG below for a side-by-side, where red is Test Jig #3.

D. woot!

syvwlch on May 19, 2011 said:

This is quite a bit thicker than Test Jig #2, which only had the drum and the escapement wheel. The frame may not be rigid enough as is, and may need additional front-to-back bracing...

pipakin on May 19, 2011 said:

Very exciting. Now I've got more to print out. Initial test of the new ratchet in PLA seemed much better, still requires a bit more force to turn then I'd like but turns with no breakage.

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