Re: [mowbot] Basic platform: worm gear motor

byron nospam at
Thu May 14 00:31:56 EDT 1998

> At 02:50 PM 13-05-98 -0700, you wrote:
> >---Dave Everett <deverett nospam at> wrote:
> >> I chose motors used for car electric windows, they came from
> >>
> >> and cost $14.97 each and outputs 40RPM, the part number is DCM-64. All
> >> Electronics have other motors that may be suitable, and specifically
> >> another electic window motor with an output speed of 120RPM.
> >
> >These motors (power window & locks) are designed for intermittent duty
> >cycle, so running them at full power for longer time should
> >theoretically damage them. What is your experience with them?
> >==
> Someone else (Robin I think) mentioned that way back when I first talked
> about getting them. The first thing I did when the platform was built, was
> run the platform up and down the lawn measuring the current for about 1hr.
> The motors were quite warm after that but not hot.
> If they do experience problems down the line at least I can replace them
> cheaply or even select another motor, but I needed to get started and the
> choice of motor was stopping me from progressing at all.

Dave, as I'm sure you well know All electronics offers a wide variety
of surplus items. Let's say for the sake of argument, your motors failed
today and you needed to replace them. Wisely you consult the latest All
electronics motor catalog pages on the Web (which incidentally were just
updated today) and for find the following contestants:

12 - 120 VDC WORM GEAR
CCL Motor # DE-25L
This very unusual motor
has been prepped with
a full wave bridge
ectifier for use with 120 Vac.
If you bypass the bridge rectifier it works very nice-
ly on any DC power from 12 volts on up. The final
drive is a 0.8" long worm gear that turns a 0.8"
diameter plastic gear at 120 RPM nospam at 12 Vdc (no
oad). Replaceable brushes. Motor body is 1.41"
diameter x 2.75" long.
CAT # DCM-96 $5.50 each * 10 for $50.00

[ BAJ comment: I think this was the one Dave was referring to above ]

24 VDC, 56 RPM
Buehler # 127E4520
Small, powerful gear
motor. Will operate at 12-24 Vdc
(32 RPM nospam at 12 Vdc). Motor is 1.18" diameter x
1.7" long. Gearbox is 1.38" diameter x 1" long.
0.2" diameter flatted shaft is 0.4" long. Gearbox
has three threaded mounting holes. 3.75" long
eads. CAT # DCM-93 $ 15.00 each

Pittman # GM8714F560
Permanent magnet,
reversible motor. Gearbox
ratio 10:1. No-load speed
899 RPM nospam at 24 Vdc, 0.25
amps. 400 RPM nospam at 12 Vdc. Ball bearings on
motor, sleeve bearings in gearbox. 3/16" dia.
shaft X 3/8" long. 1/16" diameter through hole
and snap ring groove located near end of shaft.
Front face of gearbox has three tapped 4-40
mounting holes. 1.37" dia. X 3.38" long excluding
shaft. CAT# DCM-101 $15.00 each

Toshiba # DGM-208-2A
23 Vdc permanent magnet,
reversible motor with
sleeve bearings. No-load
speed is 475 RPM. No-load current: 0.15 Amps.
With a 2.8 kg-cm lead the speed is 275 RPM. At
12 Vdc the no-load speed is 200 RPM. Shaft is
0.24" (6 mm) diameter x 0.85" long, flatted on one
side. Motor has three 3mm tapped mounting
holes on the front face of gearbox. Dimensions:
1.58" diameter x 3.38" long (excluding shaft).
CAT # DCM-99 $15.00 each

Would any of these fill in as a replacement? Why?

And if you get a chance can you tell us a bit more about the interface
between the motors and the drive wheels? I know you said you had axles
lathed but I'm particularly interested in how you interfaced the motor
axel and wheel. I didn't see a close up or drawing on the website.

Lastly, you laughed heartily at keeping the platform in the $300/$400 US
ballpark, but you never followed up. Presuming that any of the motors
above could actually be used, I fail to see where the cost comes from.
The motors are less than $50, the batteries should be no more than $100,
even a custom made aluminum frame shouldn't be $250, could it?

BTW I plan to prototype with wood. It's heavier and less sturdy than
metal, but it's cheap and plentiful and infinitely sawable, drillable, etc.

You guys just don't know how glad I am to see this list alive again.