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On Tue, Jan 10, 2023 at 11:26 AM, Carl wrote:

... slit the nut before tapping the M10x1 LH? ...

Maybe I am missing something, I am not versed in screw geometry or standards.

If I understand correctly, what would be happening is that the 7.0mm hole made to tap the M8x1.0 LH thread would get a lengthwise slit, say maybe a max of 0.3/0.4mm wide, would then be clamped so as to close that slit/gap and then threaded to M8x1.0 LH.

I think that the result would be a smaller albeit not precisely round (ie: slightly oval) hole to thread but as we are talking brass and not steel, this would not be a problem when making threading, provided due care was taken.

If for the sake of this exercise we take the slit+clamped hole to be just as round as the un-slit one, I think that what we would end up with would be an M8x1.0 LH thread made in a hole a wee bit smaller than usual practise advises, say M6.80 instead of M7.0.

When the clamp is released, the slit will then spring open and as a result the now threaded hole will go from the (estimated) 6.80mm to the nominal 7.00mm, taking the both the crest and root of the M8x1.0 LH thread further away from the lead screw's axis.

If I am correct, I think that the screw would have quite a bit of play.

Make sense?

Thanks a lot for your input.

Best,

JHM