Mach has been pretty stable for me for the last year. However, after I replaced the hard disk of the controller because the original one broke, and started using Mach in metric mode, it hasn't been very stable anymore. Not sure if the new hard disk or the metric mode have anything to do with it.

Today, I was milling the large outside chamfer with a ball endmill (don't have a holder for my large chafer tool at the moment, so this was just a work around). The x/y zero is in the center of the part. All of the sudden, in the middle of the operation, half way through the chamfer, the ball mill starts moving into the part! By the time I stopped it, it already destroyed the part as you can see.

Trying to trace down the issue, I quickly realized that x/y zero is no longer in the middle of the part. It moved by about one inch. In other words, if I moved the head to the position where the DRO in Mach would read X 0, Y 0, I was by about one inch of the center of the part. Therefore, the tool path just went right into the actual piece.

After setting the zero again in the middle of the part, I just hit program reset and ran the same code again with no issues. I can therefore definitively say that there is no problem with the actual code. Mach just randomly lost the x/y zero.

Any clue what the issue could have been? Anybody with a similar experience?
This is super scary. I sometimes leave the mill running unattended for hours.
(time to take a closer look at path pilot)

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