[machining fool]

While running a program, the Z axis just starts going down in the negative, broke the mill bit. The servo has a rotary decoder and the readout on the screen stays at the last number, not representing the movement of the Z axis. Is it the drive or the decoder? Could something have come loose? When the Z axis starts drifting down, it still indicates no movement on the screen. Help please. The electronics is an Anilam 1100m. It started out with the problem with just not responding to the numerical output and now it just takes off fast.

[machining fool]

Well, I fixed the problem. The problem had nothing to do with electronics. The split lock nut that squeezes the two roller bearing together on the ballscrew had backed off allowing play between the quill and the ballscrew. That is why the dro did not indicate movement. What was happening when the cutter plunged for a cut, it would float rather than being forced down into the cut. By tightening the two opposing roller bearings, the problem will be solved. Robert Brown.