How I Learned to Check the Simple Things First
It was a Tuesday morning in late February, and I was feeling confident. We had a batch of fifty 4140 steel shafts to get through, each requiring a 12mm hole drilled 400mm deep. The machine was a TBT ML-800, which normally runs like a Swiss watch. I had set the job up the day before, everything was dialed in, and I was ready to make chips. First hole of the day came out at 0.15mm off position. Not terrible, but not within our tolerance of 0.08mm. I tweaked the alignment, ran another part. This one was 0.12mm off. Then the third hole was 0.18mm off at the bottom. Something was wrong. ...