Re: [CAD_CAM_EDM_DRO] The specificatin of ballscews?

In a message dated 3/5/2003 2:09:24 PM Central Standard Time,
calkai@... writes:

> Could you give me some suggestion about the choice of ballscrews?
> I would lilke to build a 4'x 2' Z:10" router for woodworking.
>

Tom: I have built three "X-Y Tables", the largest by far now in England
since '86. For a 4'x2' area, I would use 1" dia. screw for the "Y" (the 2'
distance), and at probably 1.125 or even 1.25" dia. for the "X". Pitch?
Depends on the resolution you expect, and the quality of the linear bearings
you will be using, stffness of assembly, etc. But 0.5" linear move per
revolution would probably be about right. BUT... Wouldn't you prefer to be
working in METRIC???

Don't forget, a standard stepper-motor turns ONE turn for every 200 steps, so
you might want to figure the screw-pitch based on "200". For example, a BP
mill moves 0.2" per turn, so each step turning those screws would be 0.001".
So, for a woodworking machine with BALLscrews with 0.5" lead, you would have
400 steps per linear inch, assuming you USE Imperial measure. Or, perhaps if
you want to instead use METRIC, select a 20 mm/revolution screw. This would
be 20 steps/mm., or if you used x5 microstepping as is possible with Gecko
G210 drives, 100 µsteps/mm. That's pretty fine precision for woodworking,
LOL!

Jan Rowland


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