Mitutoyo threads-again.

[Ueee]

Hi All,
I know Stuart chased himself silly trying to match a mit thread some time back. I have looked but cant seem to find the thread.
Anyway, last week i bought 2 mit indicating mics, a 1-2" and a 25-50mm. They are in very good condition, work smoothly and the anvil faces are still like mirrors. There is just one problem.....the countersunk screws out of the cover plates are missing on both of them!
I checked one of the mechanism mounting screws and it seems to be the same thread. The screws measure 1.85mm across (.073"ish) and the pitch to my eyes is 60tpi.
I've checked all the standard threads i can think of but none match. Any thoughts?

[Stustoys]

Hi Ewan,
My thread wont help as it was M4.

I wonder what the story behind the missing screws is?
I assume you are looking at a very short length of thread. Couldnt be 63.4tpi could it? M2 0.4?

Stuart

[DarBee]

Hi there Ewan & Stuart,

Being an old Instrument Fitter (AKA 'Clockwinders'), I would have assumed the missing screws would be BA.
BS 93 British Association (B.A.) Screw Threads Data Charts

I have a few BA taps & dies, so tomorrow (SUN) I will have a look to see if one is close to the size you have described.

It's great to be back in the shed!! Regards, Daryl

[hillpanther]

if you couldn't find them let me know the exact size.i will send it to you from japan.there is a shop in osaka which is specialize of all kind of nut bolt screw.

[NCArcher]

BA would be my guess as well. Looks like #9 BA from DarBee's chart.

[Clubman7]

Ring MTI Qualos. They are service agents for Mitutoyo equipment.
More than likely a standard Mitutoyo screw they will have in stock.
M.T.I. Qualos

[Pete F]

I've checked a number of Mitutoyo products here and they seem to normally use M2 for case screws like that. Same as the back plates in dial indicators if that's of any use. They are made in Japan and I'd be very surprised to see anything other than metric being used.

Pete

[matthew_g]

Hi there Ewan,
If you can wait a day or two, because I have a big drive tomorrow to collect my surface grinder and the diesel engine I won on grays. I probably have what you are chasing in large quantity. I will send you an assortment on Tuesday of all the BA and miniature metric and imperial thread screws as a have thousands. I picked up bpxes and boxes of them at an auction once. And I really don't think i'll miss a few.
So just pm me your addy.
Matt

[Ueee]

Thanks Guys.
I had wondered about M2 but though .15 undersize on diameter was a bit much.
Thats a great offer Matt, PM sent.

Cheers

[Pete F]

Thanks Guys.
I had wondered about M2 but though .15 undersize on diameter was a bit much.

How did you measure the diameter?

[Ueee]

How did you measure the diameter?

Mic across the major dia, I checked several just to be sure.

[bob ward]

Its hard to imagine that Mitutoyo would be using anything other than metric threads in their instruments, but a #1 UNC screw does have a 1.8542 OD and 64 TPI.
https://en.wikipedia.org/wiki/Unified_Thread_Standard

You can buy small packets of tiny metric screws from Jaycar and similar electronics stores if you want to try an M2 in the hole.