[mowbot] cordless crewdrivers and duty cycle

Monta Elkins (Monta nospam at vt.edu)
Mon, 30 Sep 1996 09:07:09 -0400

Ron Woodward wrote:
> >> Regarding motors. My first thought is to get a couple cheap
> >> cordless screwdrivers.
> A while back I came across a great deal on these. Its the Black & Decker
> power screw driver (I can't remember the model) But it had 40 inch lb of
> torque and cost only $14 regular price.

I think the assumed duty cycle would make these unusable.
Cordless screwdrivers are in use for several minutes at a time;
Mowbot will be moving for several HOURS at a time.

Even the larger motors can overheat. My son's battery
powered car is an example; designed for 6 or 12 v
(high and low speed), I installed a large 12v battery.

Pulling him 60lbs. 'flying across the yard' (I'd guess
5 Mile per hour); they started overheating in about 15 minutes.

For mowbot the battery powered car (BigFoot) would be Pulse Width
modulated to travel MUCH slower, keeping the heat under control,
and still plenty of power for hills and lotsa' weight.

-Monta Elkins

| "All that is necessary for evil to triumph is |
| for good men to do nothing." -- Edmund Burke |
| Monta nospam at bev.net ----------------- http://www.bev.net |
| System Administrator - Blacksburg Electronic Village |