Alt-BEAM Archive

Message #05016



To: beam@sgiblab.sgi.com
From: Bruce Robinson Bruce_Robinson@bc.sympatico.ca
Date: Sat, 03 Jul 1999 22:31:48 -0700
Subject: [alt-beam] Re: gearmotors


"Travis D." wrote:
>
> Speaking of gear motors, BGMicro's "new products" page
> features this:
>
> Robot builders, start your motors! These Mabuchi motors and Molon
> gearboxes were removed from working equipment.

Yep, got one right here, hooked up to 3 C-cells (4.5 V total), and
churning quietly away at just under 6 RPM. Some comments for those of
you interested:

1) the attached wheel (BIG) is made from a plastic composite. It is
pressed on -- the output shaft has a flat machined on it, and a set of
splines as well. I couldn't remove it with hand pressure but it took
hardly any pressure from my arbor press. From this, I infer that it
takes only slightly more pressure to remove the wheel then I could exert
with my fingers.

2)That gearbox is also big. And ugly. I plan to remove the cover plate
and see if I can rebuild the gearbox in a different configuration.
However, the four mounting holes are actually threaded sleeves that act
as rivets to hold the cover on. Not the trivial task I expected. The
motor is held in place with 2 screws and can be removed easily.

3) The literature says you can't stop it with your fingers. At 4.5
volts, I can't stop the SHAFT with my fingers -- and those splines give
a good grip. However, it was trivial to stop the mounted wheel with
finger pressure.

4) The literature implies otherwise, but mine came with a large O-ring
mounted on the wheel -- a little more resiliant and "grippy" than a
typical neoprene O-ring. The diameter of the cross-section is 0.20
inches! Anyone looking for "tracks" for a tracked vehicle?

If anyone wants more specific information, mail be privately and I'll
poke around with mine a little more.

Take care,
Bruce

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