Newsgroups: comp.robotics
Path: brunix!cat.cis.Brown.EDU!agate!spool.mu.edu!uwm.edu!mixcom.com!jjwwjj.mixcom.com!user
From: clint.laskowski@mixcom.com (Clint Laskowski)
Subject: Motor Needed: 6VDC, High Torque
Message-ID: <clint.laskowski-110694133625@jjwwjj.mixcom.com>
Followup-To: comp.robotics
Sender: news@mixcom.mixcom.com (Net News Admin)
Organization: Milwaukee Internet eXchange (MIX)
Date: Sat, 11 Jun 1994 18:50:19 GMT
Lines: 35

Hello,

I'm looking for a pair of DC gearmotors to drive my latest mobile robot
design. Ideally, I need them to operate from 6VDC (although I might be able
to supply 7.2 or 8.4VDC). I need 70-100 RPM (I'll consider gearing down
from higher speeds if I must). The motors must be reversable and, ideally,
would not draw more than 2A each. I NEED AS MUCH TORQUE AS POSSIBLE! A real
luxury would be if they had quaderature HP shaft encoders installed(!)

Right now, I'm considering a surplus motor from C&H (800/325-9465) for
$27.50ea. It's the Pittman GM9413E657 wich requires 9.8VDC. It is
reversible and has the following specs:

RPM      TORQUE     DRAW
---      ------     ----
92       no-load    0.16A
63       90 Oz-In   1.00A

This motor is a little slower than I'd like, but otherwise, it seems very
nice.

I'm also considering using servo motors sold by TOWER Hobbies. I understand
they can be modified for full rotation and some of them can deliver up to
130 Oz.-In. of torque(!). However, I've heard using modified servos is a
real risk because they were never designed for full rotation and can be
stressed if used this way.

Size and shape do not matter at this point, but ideally the motors would be
the typical "can" shape rather than the "pancake" shape used by some
manufacturers (Brevel, etc.). 

Does anyone have any suggestions for suppliers and/or part numbers? I'm
open to (and maybe prefer) surplus vendors at this point.

I'll be glad to post a summary if there is enough interest.
