Just got my little Boxford mill set-up to work  with Mach3, and excited to be cutting metal at last
Tried cutting a 20mm square in a piece of brass with a shallow cut and 0.080 cutter.
It cut the square ok so I increased the depth of cut and re-ran the program using the same zeroes.
This time it was slightly off from the original   cut. A third run showed similar errors.
I think it could be a backlash problem or dropping steps.

Anybody got a straight forward procedure for checking out these possibilities?

Thanks
TMSmith

Hi, TMSmith

The easiest way is with a dial indicator, Set it up on the table, Move into it some, Zero dial indicator, Move in more.   

Move the same amount opposite direction, Dose the dial indicator return to zero, If not there is backlash in your axis.

This is just checking backlash, Not steps per unit/Calaibration

Hope this Helps, Chip

You also could have a motor coupling that is slipping... and or electrical noise.

Thanks for the replies.
I found the info in the maual!!!    and carried out the checks with a dial indicator which suggested the axis were pretty close, within a couple of thou and reproducible.
Will carry out more checks on other things mentioned. But I am becoming suspicious that the plate could have crept under the cutter forces.

More trials needed

Thanks

TMSmith