Hello all. Have our Bridgeport R2C3 with a TNC145 making chips. Got everything working including using a Windows XP computer to store the programs and then transmit them back to the controller. Now have a new problem.

Last week was first one in limited production with it. Broke a couple of tools and figured it was just our bad programming, but now that we are doing larger runs of 20+ parts each it appears that the Z axis is not returning back to zero, rather it is loosing a bit in the negative direction on each pull up. After about 3 or 4 parts the lost distance is enough to require the knee to be dropped to compensate if you want to keep running. You can keep this up till you run out of z travel. We are using it like a large automated drill press so it's not critical, but have some parts to make where it will be (stepped milling).

Machine has the SEM servos and I don't think they loose steps. How do I trouble shoot this? Is it the servo, the encoder or the board or something else I should check?

As always, I really appreciate the help I have gotten off of this forum. Dennis