Question #6286   Submitted by Answiki on 06/22/2022 at 07:09:16 PM UTC

What diameter should I pre-drill for an M8 tap?

Answer   Submitted by Answiki on 06/22/2022 at 07:10:19 PM UTC

The pre-drilled diameter of an M8 x 1.25 thread is 6.8 mm.


The pre-drilled diameter for tapping is given by the drilling diameter minus the pitch. For a standard M8 x 1.25 tap, you need to drill to 8 - 1.25 ≈ 6.8 mm.

3 events in history
Question by Answiki 10/14/2022 at 07:44:05 AM
What diameter should we pre-drill for an M8 tap?
Answer by Answiki on 06/22/2022 at 07:10:19 PM

The pre-drilled diameter of an M8 x 1.25 thread is 6.8 mm.


The pre-drilled diameter for tapping is given by the drilling diameter minus the pitch. For a standard M8 x 1.25 tap, you need to drill to 8 - 1.25 ≈ 6.8 mm.

Question by Answiki 06/22/2022 at 07:09:16 PM
What diameter should I pre-drill for an M8 tap?
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