M4 x 0.75mm pitch CSk machine screws

Anyone know a supplier of these please?

This is not a standard size. M4 x 0,70 is Metric Coarse.

JA

Are you sure the thread is not 3BA?

I know!!!

I seem to remember a thread where someone wanted the same, they were used to hold some sort of panels, can't find it at the moment.

It wasn't fixing light switch/power socket face-plates to pattress boxes, was it ?
DaveD

Edited By Meunier on 22/08/2019 20:54:25

Some idea of the application would help responders offer some remedial ideas.

If they are for panels in sheetmetal work, and only a few threads, there may be ways to use more available fasteners.

.75 mm pitch ( .0295" pitch) is very close to 34 tpi (.0294" )) . If you have a lathe than can cut 34 tpi you could make your own screws.

34 tpi (.0294" pitch) is close to 32 tpi (.0312" pitch) , only .0017" difference in 32 to 34 pitch, and 4.0 dia is .157". A stock #8-32 machine screw is .164 dia x 32 tpi. If not too many engaged threads are involved you could probably overtap the holes (if tapped) #8-32 and use #8-32 screws which are widely available in many materials, lengths, and head styles.

You could probably overtap the holes (if tapped) M4 x 0.7 and use M4 std screws, again if not too much thread engagement is needed. M4 are also available in lots of materials lengths and head styles.

If you can find some 3BA screws you could probably use them although their pitch is nominally 0.73mm not 0.75 so if there are a lot of engaged threads the screws might jam.

If you ever need to replace the screws in future years you might be glad you used #8-32 or M4 x 0.7 - BA screws are less and less available, it seems.

Edited By Jeff Dayman on 22/08/2019 21:09:18

Edited By Jeff Dayman on 22/08/2019 21:09:36

Edited By Jeff Dayman on 22/08/2019 21:11:54

It's for a pair of Cozette Blowers which are French, which is why it's an odd metric size!

Tracy tools list the taps and dies for these if you don't fancy screwcutting them.

Are the threads in castings, bar, sheetmetal? (not familiar at all with Cozette blowers)

How deep / how many threads are there in the material?

What is the material the threads are in?

How many screws / holes are there?

I agree with the others that they are probably 3BA. This is one source on ebay. but there is than one match searching for "3BA screws.

Les.

A 4 x 0.75mm pitch thread was part of the old French standard for metric threads specified by the Comite de Normalisation de la Mechanique. Threads from 6mm diameter upwards conformed to the ISO system. The old French standard below 6mm has now been replaced by the ISO system.

Andrew

Yes I agree. Working on early french cars has made my collection of metric taps and dies bigger than all my other taps and dies. I have 5 different size M10 taps!

Is anyone really going to screwcut such a thread when they can buy taps and die?. Anyone who gets work done, that is.

Yes is the answer, it all depends upon how many items you need.

I know what you mean. “Ally Barber” would gladly supply a million from China. Not so good a price, or availability, if one only wanted four or five!

GIYF.

www.classicandexotic.com/store/p-3865-m4-075-screw.aspx

Not a cheap option with shipping, I guess.

Neil

Drop CW Fasteners a question. They stock all manner of fastenings.... **LINK**

.

I may be wrong, but I think KWIL was answering the question by Nicholas Wheeler 1

[quote] Is anyone really going to screwcut such a thread when they can buy taps and die?. Anyone who gets work done, that is. [/quote]

MichaelG.