Spinning without pendulum

[ruste...@prototribe.net]

A small milestone in the tinkering i've been doing. The entire geartrain is spinning smoothly with a 1693 gram (3.73lbs) weight which happens to look a lot like a pipe wrench. I'm not entirely happy with how much weight its taking to spin as compared to the original demo (770 grams), but the gear between the hour and minute gears isn't mounted ideally and can wobble a bit, so i'm hopefull some tweaking there can decrease the weight requirement (or alternately increase power applied to the escapement.)

With the current setup and length of line, once ticking should be able to run for nearly 48 hours. As it stands now it takes almost 4-5 minutes to run out with a free-wheeling escapement gear.

I think one of the keys things that makes this work as well as it does without bearings is rigid and perpendicular axles and tight tolerances of the gears against the axles.

Here's the video:
http://www.prototribe.net/vidplay/prototypeclock2_demo1.html

This is that part count so far. The precise lengths of the screws were limited to what I had on-hand and aren't always the perfect length.
Case
22 printed parts (so far, might change)
2 mounting screws
2 washers
2 40mm M3 screws
2 M3 nyloc nuts
`
Geartrain
6 printed parts drum to escapement wheel
9 washers
5 M3 nylock nuts
2 40mm M3 screws
2 25mm M3 screws
1 20mm low profile M3 screw



So what remains?

• Ticking! - making the escapement work and figuring out the pendulum length
• What time is it? - Adding visual indicators of the time (hours and minutes) I'll probably stick with numbers on the gears and a fixed window for the currently selected hour/minute.
• Refinements - adjustments to make the screws fit better, tweaks to the case, possibly making the gear spokes fancier, etc...
  

If anyone wants the files for this now, let me know. I'm holding back on releasing everything on Thingiverse until I have a chance to try the escapement in case I needed to change a number of the parts. (Which could be a lot) But I have no problems if someone really wants to get started early. When I upload i'll probably also have a different separate set of parts for the case to be printed on a Replicator as I think that can be done in 3-5 pieces instead of the current 21 on my TOM.

Let me know if anyone has any pointers or questions.

Thanks,
Rustedrobot!

[Mathieu Glachant]

That is just gorgeous, congrats! :-)

If the escapement is a little reluctant to start, we can probably help diagnose if you post some close up video of it. I wouldn't mind having a working thirty tooth escapement, would come in handy for a four gear clock.

[ruste...@prototribe.net]

Thanks!

I ended up trying to get it ticking last night and sort of succeeded.
Takes about 10-12 lbs to get it to tick mostly reliably (inaccuracies in
the escapement wheel catch it sometimes). And at that point the upper
case starts twisting due to the weight, but impressively it still ticks.
I need to add a good bit of reinforcing for the top two gears and move
the weight off to the side so it doesn't interfere with the pendulum.
I'll try and post video this evening. Is there any technical reason why
we can't try a 30 tooth club foot escapement wheel?

Also, apologies on the size of the pic in my last post. For some reason
it pasted as png instead of jpg!

[Mathieu Glachant]

Since I was able to add an extra factor of two in the gearing of the
clock, and I didn't want to mess with an escapement that did work, we
stuck to the fifteen teeth for the Clockathon versions. The club feet
require the teeth to be much more sharply raked back to that the
escapement arm doesn't it their stem, and on the small size of
escapement wheel in the current design, there just isn't room.

I think we can probably increase the size of the escapement wheel,
make the club feet much smaller, lose some of the raking and get back
to thirty teeth. It will just take a little tweaking to dial it in, so
I won't even attempt it until we do another Clockathon or I get my
printer back from the buddy I loaned it to.

With a thirty tooth escapement and keeping the extra gear ratio, we
could go to a 25cm pendulum instead of 1 meter one, i.e. from a
grandfather clock to a mantelpiece clock... which will have much less
drop for a drive weight and perhaps require a spring drive? A spring
drive strong enough to replace several pounds of weight is going to be
scary, tho.