Bearings, bushings, and printed sleeve extensions...
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Mathieu Glachant
Feb 7, 2012, 8:35:48 AM2/7/12
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I've heard the arguments for using bearings as a way to protect the printed gears from wear, and the goal of keeping the vitamin costs down by opting for skate bearings... But we really only need bearings for parts with higher radial loads, such as the drum, and skate bearings are hard to fit in gears with smaller pinions (ie they limit the gear ratio achievable per gear).
For parts that have low radial loads and really just need wear protection and perhaps some tighter tolerances vs the shaft they rest on... I think all we need are some bushings, ideally cheapily and easily sourced/made.
I'm still a huge fan of cutting some metal tubing to the thickness of each gear (inc. any sleeve extensions for concentric shafts), and I think it may be the ideal solution for most gears, with skate bearings used only for the drum.
Much as i love the specially made brass tubes from the hobby stores, it would make even more sense if we can find a combo of easily found hardware to provide the shaft, one size tubing that fits it snugly, and another that fits over that with enough room for a printed sleeve extension between the two. Something from a hardware store sold for pennies to the inch, and easily cut to size without crimping.
For parts that have low radial loads and really just need wear protection and perhaps some tighter tolerances vs the shaft they rest on... I think all we need are some bushings, ideally cheapily and easily sourced/made.
I'm still a huge fan of cutting some metal tubing to the thickness of each gear (inc. any sleeve extensions for concentric shafts), and I think it may be the ideal solution for most gears, with skate bearings used only for the drum.
Much as i love the specially made brass tubes from the hobby stores, it would make even more sense if we can find a combo of easily found hardware to provide the shaft, one size tubing that fits it snugly, and another that fits over that with enough room for a printed sleeve extension between the two. Something from a hardware store sold for pennies to the inch, and easily cut to size without crimping.
Matt Griffin
Feb 7, 2012, 8:55:14 AM2/7/12
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If folks do hardware store research and come up with somethings to try, I'll definitely purchase some options to have at the workshop for any and all to experiment with.
Thanks,
Matt
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Mathieu Glachant
Feb 7, 2012, 9:24:06 AM2/7/12
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I'm gonna see if I can find a hardware store around here. :-)
Benjamin Fraser
Feb 7, 2012, 9:26:38 AM2/7/12
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I've become a big fan of these 5mm bearings. They're more expensive than skate bearings but not outrageously more expensive. Right now the vitamin costs sit around $25-30 for the bearings and threaded rod. I think that's pretty reasonable. Also, you only have to source two parts which I think should be a big consideration.
5mm bearings ($1.49 ea.): http://www.vxb.com/page/bearings/PROD/5mm/Kit2029
Skate bearings ($.97 ea): http://www.vxb.com/page/bearings/PROD/SkateboardBearings/kit7602
Mathieu Glachant
Feb 7, 2012, 9:30:53 AM2/7/12
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Don't forget the $4 in pennies for the weight and pendulum! ;-)
We can always publish different versions of the clock for different vitamin kits.
We can always publish different versions of the clock for different vitamin kits.
MakerBlock
Feb 7, 2012, 11:23:59 AM2/7/12
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Copper piping is on the expensive side, but if you could find just a
little bit of it or could share the cost with others, it is pretty easy
to cut to size without crimping using a pipe cutter like this:
http://www.lowes.com/pd_249283-943-35012_0__?productId=3234401&Ntt
little bit of it or could share the cost with others, it is pretty easy
to cut to size without crimping using a pipe cutter like this:
http://www.lowes.com/pd_249283-943-35012_0__?productId=3234401&Ntt
MakerBlock
Mathieu Glachant
Feb 7, 2012, 11:27:13 AM2/7/12
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Alternatively, if we switched to smooth rod instead of threaded, wouldn't the wear on the gears' hubs get much better?
Che-Wei Wang
Feb 7, 2012, 2:56:56 PM2/7/12
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I would go with hi precision shafts, shaft collars and bushings for
the best fit ( so there's less wobble) and less wear.
the best fit ( so there's less wobble) and less wear.
Also, ideally each gear would be attached to it's own shaft so its
supported by two bushings or bearings on the walls (so the shaft and
gear spin together (less wobble and wear) ) rather than the bearings
mounted inside the gear that spin freely on the shaft.
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Mathieu Glachant
Feb 7, 2012, 3:04:15 PM2/7/12
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Ahhh... Good point, that's definitely how they do it in watches. Something to keep in mind for anyone trying to go smaller!
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