Subject:
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Re: Mechanical pneumatic piston
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Newsgroups:
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lugnet.robotics
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Date:
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Fri, 10 Oct 2003 04:24:07 GMT
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Original-From:
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Steve Baker <sjbaker1@airmail.net+spamcake+>
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Viewed:
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1771 times
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Mike Thorn wrote:
> At 11:38 AM 10/9/2003, you wrote:
>
> > >
> > > Nope. Worm gears are not an integral number of studs long. They • are about 1/4
> > > of a stud short. Not enough for a small pulley (1/2 bushing).
> >
> > I'd be very interested to know the reason why LEGO chose to make the
> > worm gear
> > so short :-(
>
>
> Yes, it seems rather odd. It really wouldn't have affected the design of
> the gear at all. Just extend the spiral another fraction of an inch.
> Simple, really.
>
> If it's right that they're about 1/4 or 1/8 stud short, you ought to be
> able to line up 4 of them and stick in a half bush.
The end of the helix on one worm gear lines up exactly with the start
of the helix on a second worm gear. If the gears were a quarter stud
longer, they wouldn't have this useful property unless Lego also changed
the pitch of the helix.
However, if they did that, then either:
a) The teeth would have to be a bit wider apart - and it wouldn't mesh
properly with other Lego gears.
b) They'd have to change the slope of the helix which would mean that
one revolution of the worm gear wouldn't be an exact sub-multiple
of the number of teeth on the gear it's meshing to - and it would
be very hard to calculate nice exact gear ratios. Also, the slope of
the gear's helix is fairly critical to it functioning as a worm gear,
you don't have much 'wiggle room' here.
They had to compromise on one of those properties - and the exact length
of the gear was obviously the thing they decided to give up on.
---------------------------- Steve Baker -------------------------
HomeEmail: <sjbaker1@airmail.net> WorkEmail: <sjbaker@link.com>
HomePage : http://www.sjbaker.org
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Message has 2 Replies:
 | | Re: Mechanical pneumatic piston
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| (...) If you look at the 1x4 rack (or any of the other sizes, for that matter) you'll see that actually there is more slop available than you'd think. The gears mesh with them fine, The worm gear similarly could have been stretched just a tiny bit, (...) (21 years ago, 10-Oct-03, to lugnet.robotics)
| | | Re: Mechanical pneumatic piston
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| (...) I'm not sure I agree with that. It seems to me that if you made these worms from one great long string, all you need to do is cut them wherever you want a new one. The helii (is that a word?) would still line up. I don't see why they couldn't (...) (21 years ago, 10-Oct-03, to lugnet.robotics)
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Message is in Reply To:
| | Re: Mechanical pneumatic piston
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| (...) Yes, it seems rather odd. It really wouldn't have affected the design of the gear at all. Just extend the spiral another fraction of an inch. Simple, really. If it's right that they're about 1/4 or 1/8 stud short, you ought to be able to line (...) (21 years ago, 9-Oct-03, to lugnet.robotics)
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