Re: backlash testing

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?

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.

At 02:00 AM 2/4/01 +0000, you wrote:

>hey guys
>I have some backlash compensation through CNCPro but have figured out
>that I really don't know what is the best way to figure it out. The
>way I did before was to out a dial indicator in the vise and that on
>the mill. I then put the point of the indicator against the spindle
>and moved my axis back and forth a few mm and then checked to see if
>it returned back to "0." Well while playing around last night I
>noticed that no matter what compensation I put into CNCPro the dial
>indicator for the most part comes right back to 0. For example I have
>tried .01 to 1 and what I have found out (using 1 as example) is that
>the machine initally compensates 1 then moves the few mm then
>compensates 1 again (this inturn makes it as no compensation was
>made) back to 0. I have tried running the axis back and forth 5 time
>and it returns back to 0 on the indicator. IS this right??? Do I need
>to test for backlash compensation by making a circle? Is it possible
>for the machine to have no backlash?? (Sherline 5410 mill). Kinda
>confused here. any help.
>thanks as always!

Hugh Currin
Klamath Falls, OR