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What does the modelled diameter of a threaded hole say?

bruce_fischer469bruce_fischer469 Member Posts: 16
Hi there,

I don't understand the meaning of the modelled diameter of threaded holes (see e.g. diameter of 2.571 mm for a M3 thread in the screenshot). It is not the standardized core diameter and I guess it was not chosen randomly. Therefore, I would like to ask what does it stand for.

Best regards


  • Options
    glen_dewsburyglen_dewsbury Member Posts: 603 ✭✭✭
    Drilled pilot hole for tapping.
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    bruce_fischer469bruce_fischer469 Member Posts: 16
    Where do did you get the value from? According to ISO 724 it shall be 2,459 mm for M3 and not 2,571 mm.
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    glen_dewsburyglen_dewsbury Member Posts: 603 ✭✭✭
    Changing the fit class and pitch will change the drilled hole size.

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