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In lugnet.technic, Brian Davis wrote:
> OK, after struggling with precision in a lead-screw assembly for quite some time
> now, I've just got to ask because I don't know the answer and it's bothering
> me...
>
> Can ANYBODY give me a possible good reason for the length of the worm gear? why
> oh why couldn't LEGO have made it exactly 2 units long, instead of
> 1-point-almost-two-units long?!? That slight slop can really complicate things.
>
> Yes, I know about pre-loading things, gearing down, etc. - I'm just wondering if
> there is a fundamental mechanical reason why they couldn't have increased the
> pitch very very slightly and extended the worm gear very very slightly. Wouldn't
> that have worked?
Hi Brian,
If you're struggling with worm gaps for your leadscrew, this pic of my crane
worm gearbox might help:
http://www.brickshelf.com/cgi-bin/gallery.cgi?i=2840361
The worm is two worms long, plus two pairs of old type (crennellated) half
bushes (small pulleys) and an old type 14-tooth bevel gear, making 6 studs
length in total.
I also found that 5 worms and a 14-tooth bevel gear fits on a 12-stud axle with
axle extenders at either end. I gripped the worm with 3 8-tooth cogs to make a
leadscrew: http://www.brickshelf.com/gallery/mbellis/Technic/leadscrew.jpg
Some of the old, discontinued parts provide odd measurements that are very
useful when we do precision engineering!
Mark
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Message has 1 Reply:
 | | Re: Worm gear... whence the length?
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| (...) Thanks Mark - those are nice designs. In my case I needed the precision, but I also needed a very compact implementation *and* it had to mount to an NXT motor: (URL) pretty happy with the design, but the slop really needed to be compensated (...) (18 years ago, 22-Jul-08, to lugnet.robotics)
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Message is in Reply To:
| | Worm gear... whence the length?
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| OK, after struggling with precision in a lead-screw assembly for quite some time now, I've just got to ask because I don't know the answer and it's bothering me... Can ANYBODY give me a possible good reason for the length of the worm gear? why oh (...) (18 years ago, 19-Jul-08, to lugnet.technic)
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