We purchased a used 3 axis CNC Router (home built) running WinCNC with Anaheim Automation stepper motors and drivers.
All was well for a year or so, then we starting having problems with the Z axis dropping down and gouging the part. The PC display (WinCNC) shows the Z axis coordinates that should be cutting, but it keeps dropping lower and lower into the part.
It seems to be temperature related. It always starts out fine, but then as the transformers and driver boards start to heat up, the Z axis suddenly starts dropping down into the part. We thought that the Stepper Driver Boards may be overheating (Anaheim BLD 75) and sometimes a red light would turn on the Z axis board. We replaced the board and attempted to avoid overheating, but the problem is getting progressively worse. It runs shorter and shorter times before the Z axis starts dropping. We've also replaced some of the stepper motors.
Most recently, we cut with no load (moving but not cutting any material) fine for several minutes, but as soon as we start cutting and experience a load, the Z axis drops. In this test program, we're cutting a flat plate, so there the Z axis is not moving via the program at all. Most of the movement is on the Y axis with small stepover on the X axis after each pass. So the Y axis is doing most of the work, but the Z axis is what fails and drops down.
We're at a loss to find the problem. I've just ordered a replacement PCI 7200 board from WinCNC to see if that could be the problem.
Any suggestions of what might be causing this?
Thanks,
Greg