M4 x 0.75mm pitch CSk machine screws

[Russell EberhardtParticipant @russelleberhardt48058]

It would almost certainly be French Automobile Thread, a slightly different spec. to the old French Metric Thread. I still have a few taps and dies for it from working on vintage Morris cars which used French Automobile thread on their engines but with W.W. hexagon sizes so that UK garages could use their existing spanners. Unfortunately I don't have a 4 x 0.75 die – sorry.

For reference the spec for French Automobile Thread can be found about 2/3 of the way down this page:

**LINK**

Russell

[Russell EberhardtParticipant @russelleberhardt48058]

Just found this on a French site:

**LINK**

It is a bit expensive but if you need a number of screws . . .

The interesting thing is that the dies are made by Dormer to BS1127:1950!

Russell

[Howard LewisParticipant @howardlewis46836]

Purely as a comment re fasteners for switch patresses. I thought that with metrication, the threads had changed from BA to 3.5mm diameter x from memory 0.5mm pitch?

Howard

[Anonymous]

Posted by Howard Lewis on 23/08/2019 16:21:08:

………… from memory 0.5mm pitch

Ooops.

When my electrician said he'd leave it to me to fix some of the old sockets in my replacement kitchen I bought M3.5 x 0.6 taps.

Andrew

[Howard LewisParticipant @howardlewis46836]

Thanks for putting me right Andrew!

Moral: don't trust to memory. Should have looked at Tracy Tools brochure, as they sell them!

Howard

[AdrianRParticipant @adrianr18614]

Last August at the Lincolnshire Steam Rally I picked up some taps. I recently came across them again, and popped the M4 in my metric set. Yesterday I used it for the first time to tap holes for the DRO on my new mill. It puzzled me for while why the screw would not go in very far. Took me a while to notice the pitch on the tap!

Live and learn

Adrian

[Clive HartlandParticipant @clivehartland94829]

try pts_uk.com. stainless steel M4 x .75 c/sunk screws.

[Author]

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