Re: [CAD_CAM_EDM_DRO] Positioning

>I have read on another forum that retrofitting ball screws to a
>convention mill, say a Bridgeport, reduces the power needed to move the
>table - both by the operator and by the cutter. One comment was to the
>effect that with ball screws, hand machining became quite difficult.
>What I am interested in is how does one determine the necessary holding
>torque of stepper motors (or other drivers) to avoid the table being
>moved by the cutter?
>
>Regards, John

I have ballscrews on my 10x50 retrofit. I would not say that they have made hand machining more difficult. As long as your chip load is correct the friction of the table and the inactive servo is more than sufficient to keep the table in place - if you're really concerned, you could put the table locks on in the direction(s) you're not using. However, I have had the table move in a crash. Of course, that particular crash also moved the head so I don't think that is really common. :D

A tap can pull the quill down/up when the servo is off. However, it has been my experience that it is more likely to pull out of the vise before it moves the quill...

Things might be different with a smaller machine.

--CS