Subject:
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Gear train friction?
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Newsgroups:
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lugnet.technic
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Date:
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Mon, 4 Dec 2000 19:36:16 GMT
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Viewed:
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2242 times
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One of the tough problems in building a clock is to design a very low friction,
very tall gear ratio drive. I want the spool to turn around somewhat less
than once every half hour, and the escapement to turn once every six seconds,
so I need around 1:350 drive. I've been using:
8:24 -> 8:40 -> 8:40 -> 8:40 = 1:375
For every one turn of the spool, all of the axles in the drive train make a
total of:
1+3+15+75+375 = 469 axle turns worth of friction
Also, I can total up how many times a pair of teeth mesh each time the spool
turns:
24 + 120 + 600 + 3000 = 3744 geartooth meshings of friction
I would really like to reduce the friction. I am going to try to use the large
turntables fitted with plates to make axle holes. This could give a train like:
8:56 -> 8:56 -> 8:56 = 1:343
1+7+49+343 = 400 axle turns worth of friction
56 + 392 + 2744 = 3192 geartooth meshings of friction
So this drive train should have about 15% less friction.
If Lego provided a huge 2800 tooth gear, I could have a system that reduces the
friction another 13% or so:
8:2800 = 1:350
350 axle turns worth of friction
2800 gear tooth meshings worth of friction
Lubrication might help, but that is a sort of non-Legoy solution, and I am not
sure what to use. Maybe a dry lubricant like graphite or spray teflon would be
best.
Any suggestions for designing an efficient drive? Am I analyzing friction
correctly?
Reducing the friction and improving the energy transfer of the escapement would
lead to the most dramatic improvement, but this is really tricky.
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Message has 2 Replies:
 | | Re: Gear train friction?
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| Amnon, I've also found a not in-significant source of friction is the bushes against the beams (or whatever your axle goes through). I've reduced this a bit on occasion by not using bushes to hold axles in position, but having a brick at each end, (...) (24 years ago, 4-Dec-00, to lugnet.technic)
| | | Re: Gear train friction?
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| (...) Hello, I stumbled across your posting about the continuos loop chimer and it blew my mind. So I decided to join lugnut I'm also curently working on a weight driven pendulem clock and I'm going to try to build your device. I originaly tried to (...) (24 years ago, 6-Dec-00, to lugnet.technic)
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