If the drill is still in good condition, then I would not expect that the occasional bit of carbide is getting embedded in the bottom of the hole and taking the bar out.
Is there a possibility of a chip adhering to the hole? Maybe you need a fraction of a second of dwell at the bottom of the hole just to ensure that the hole gets cleaned at full depth. At 2200 rpm, the in and out might be so fast that the depth is inexact, particularly if the part has some flex.
Have you tried pecking to create the flat at the bottom? I personally hate facing holes flat in the lathe, its always an aggravation.
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(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management) |