[ATM] Mirror Grinding Machine

[James P Crombie]

Shailesh
   I don' know if you can get enough torque out of stepper motors to 
drive a machine at speed.  My grinder uses a 1/2hp electric motor 
running at 1800rpm,  and reduced to between 30-60(variable transmission) 
Thats a 30-60 times increase in torque from the motor, less 25% for 
frictional losses in the drive line.  The one spec I could find on motor 
torque gave a figure of 12ft/lbs at 50% usage.  Multiply that by 20-40 
and you have a lot of torque.  I don't think it needs all of that and 
through most of the grinding process there is not a lot of resistance, 
but as you get down to the fine grits ans especially at polishing there 
will be increasing torque requirements.  I think a stepper motor may be 
alright for the overarm but a small AC motor properly geared down would 
work better.

James Crombie
Mirror Grinder Page
http://www.jamescrombie.com/pics/

On 31/03/2010 5:47 PM, Shailesh Dalvi wrote:
> Dear All,
>
> I want to make machine to grind and polish 5" flats and 7" f/4 mirror.
> machine is based on waineo design. I am planning to use two stepper motor, one for
> spindle and other for overarm. Few questions...
> 1) What torque is needed for spindle motor to polish 7" mirror.
> 2) What force is needed to drive overarm?
> 3) Dose the torque and force are directly proportional to area?
>
> Regards
>
> Shailesh
>
>
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