Homebrew PCBs

On Tue, 28 Jun 2005 08:36:23 +0200, mikegw20 <mikegw20@...> wrote:

> Now I have never built a CNC anything and I am not overly mechanical.
> Right that is my qualifications out of the way...
> I was thinking about high torque motors to drive a linear thread and I
> thought about those really cheap cordless drills.  That is idea pt1.
> Now of course you need some sort of feedback for the position, the
> normal way would be to put a shaft encoder on the drive.  My thinking
> is that if you used a linear encoder then you would get absoulte
> positioning thereby negating the need for backlash compensation.  Now a
> quick look around ebay reveals that linear encoders are not cheap.  So
> has anyone used optical mice for a linear encoder? (idea pt b)
> Here endith todays musings.
> Mike


cordless drills usually use a motor what the model-vehicle builders would  
call similar to a "speed 600".
Not a bad motor, and you can get replacements really cheap as well as  
better motors the same size.

I would try to find drills with metal gears for this purpose. I recently  
bought a very cheap one with plastic gears, it is still working, but i'm  
always expecting it to fail any time. It was cheaper than a replacement  
battery for a better drill.
There are often ebay lots of many drills.


As for linear encoder, there are those striped plastic strips in printers,  
but a much easier solution would be to use digital calipers and use the  
data-out, 'cause you would get absolute position not only relative.  
Probably more expensive than shaft encoders and certainly more expensive  
than steppers.


ST