Subject:
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Re: 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 22:25:54 GMT
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Viewed:
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3930 times
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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, that the axle (almost) butts up against. It does allow a
bit of length-wise motion, but reduces the friction.
ROSCO
Amnon Silverstein <amnon@best.com> wrote in message
news:G526GG.IKB@lugnet.com...
> 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 1 Reply:
 | | Re: Gear train friction?
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| (...) The length of one axle is normally slightly shorter than a corresponding beam, ie. an axle #4 is slightly shorter than a 4 stud beam. So this is probably why you achieve some slack when putting bricks on either side of the axle to support it. (...) (24 years ago, 5-Dec-00, to lugnet.technic)
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Message is in Reply To:
| | Gear train friction?
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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 (...) (24 years ago, 4-Dec-00, to lugnet.technic)
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