Re: [CAD_CAM_EDM_DRO] Re: backlash testing

Hugh Currin wrote:

> Tauseef & all:
>
> As I understand backlash it is the slop or free-play between the lead screw
> and its nut. In moving right, stopping, then moving left some lead screw
> rotation is needed to take up the slop and thus doesn't move the
> table. This rotation without table motion is backlash?

Yes. It is also called "Lost Motion", as the change on the handwheel
dials does not correspond to actual table movement.

> The way I've tried to measure it is to move the table one direction (say
> right) until the dial at the lead screw handle reads zero. Then zero the
> DRO, or set up an indicator between the spindle and table to read zero,
> without touching the lead screw handle. Then move the table the other
> direction (left) using the handle very slowly while watching the DRO (or
> indicator). Once any motion is seen on the DRO (indicator) stop. The
> reading on the lead screw (difference from zero) is the backlash.

Yes, this is a fairly good way to measure it.

Jon