How much deeper is the bottom hole diameter of the thread compared to the thread depth?

During the process of drilling blind thread holes, we encountered many cases where the bottom holes were not deep enough. This resulted in difficulties in customizing the taps, with the iron filings being very coarse and unable to be curled, causing severe clogging, and serious breakage of the taps.

Especially when performing fully automatic tapping, it causes the equipment to freeze and triggers an alarm.

The thread depth of M10 is 20mm. The depth of the bottom hole drilled by the drill bit is 27mm. When tapping blind holes (non-through holes), since the tap has guiding teeth and the tapping machine has depth tolerance, the depth of the hole should be greater than the length of the thread.

The depth of the blind hole can be calculated according to the following formula:

1. The depth of the hole = the depth of the required thread + 0.7d

2. Nominal diameter d, the insertion depth h for through holes, the insertion depth H for blind holes, and the tapping depth H1