Originally Posted by
SCzEngrgGroup
The ONLY way the tap could possibly be "under compression and held in the hole" is if you don't unscrew it far enough to get it completely clear of the threads, and out of the hole. If makes NO difference whether its under tension or compression at that point - If you move the T/C head up, down or sideways, you WILL break the tap, and/or gouge the top of the part. The programming MUST turn the spindle enough turns, and raise the head high enough, to get the tap completely free, and above the top of the hole. If you don't, it doesn't make one bit of difference whether it was in tension or compression before getting free of the hole.
Regards,
Ray L.