Why Is Your CNC Machine Losing Position?

A machine that's always been a bit sloppy is one problem. A machine that USED to be spot-on and isn't anymore — that's drift, and it only gets worse from here. 

• Mechanical wear — worn ball screws and linear guides create play. The machine commands a position; the slide doesn't quite get there. 

• Feedback faults — encoders clogged with swarf, degrading, or wired wrong feed the controller bad position data. 

• Thermal expansion — cold machine, no warm-up cycle, and the whole frame grows as it heats. Drift that settles down by lunchtime is thermal, not mechanical. 

Nine times out of ten it's more than one of these stacking up at once. 

 

Clamp a DTI on the axis carriage, zero it, jog back and forth. Doesn't return to zero? That gap is your backlash. 

Compare it against the tolerance in your manual. Over spec? The ball screw needs attention. 

 

Backlash compensation in software buys you accuracy short-term. It doesn't fix worn steel underneath it. 

Sooner or later that's a ball screw service or replacement job — and we can carry out both.