Re: [ATM] grinding and polishing machine

["Dave McCarter" <dmccarter@sympatico.ca>]

> If you want to get fancy with motors, there are DC input motors
> that will give a huge range of speeds just fron the controller
> alone.  The provblem tho with doing it this way is that the
> torque is constant (or even going down at lower speeds) which is
> contrary to what is really desired which is larger mirrors want
> to go slower as they need more torque than a smaller mirror to be
> ground and polished.  The DC motor trick doesnt' give you the
> gearing torque multiplication that a pulley system will give you.

Bob, I hate to disagree, but I've been using a gearhead DC motor for quite
some time now, and they have loads of torque. The motor I use is made by
Bodine, runs on 130 volt max at 0.7 of an Amp, and this will give 15 RPM at
166 pound inches of torque. On the table I run a 2 inch pulley to a 15 inch
pulley with V belt for slow rotation and use another motor with direct drive
to the over arm. It will complain when the lap gets dry, but it does not
stop. For the DC I use a variable transformer into a high voltage bridge
rectifier and capacitor bank, out of a computer switch mode supply.

Dave
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