Morris Minor Owners Club

Hi all,
Can anyone tell me the thread size of the fixing studs on the back of a Smiths 30 0 30 ammeter so I can get some nuts?

I’m going to say 2ba, as with a lot of electrical stuff.

Thanks, I will let you know.

Turns out that the clamp stud threads on the Smiths Ammeter are 3ba.
Not sure if it's the same for all instruments though.

Oh dear, sorry.

The single securing stud for Smiths oil pressure gauge PG1301/00AR is not 2BA or 3BA.
I have a full set of original LAL BA taps and dies and none of them fit.
I have yet to determine what thread it is. Once I know I will post on here.
Phil

Just one example of a great number of thread gauges. Some are likely better than others, of course. I have two or three similar sets knocking around plus several hexagonal discs I brought home from Ca. They are all in use occasionally.

https://www.ebay.co.uk/itm/372165778297 ... BMxryCmfZg

Having used my Moore & Wright vernier gauge, Moore & Wright thread gauges and referred to my ZEUS data charts this what I have decerned.
The securing stud is 5/32" O.D.
The thread TPI is 32.
So, with reference to the ZEUS chart, I believe the thread to be 8 - 32 UNC. (Unified screw threads for attachment under 1/4").
I have just ordered a 8 - 32 UNC tap and die set to prove or disprove the thread.

I believe the thread to be 8 - 32 UNC

As long as the thread form is 60 degrees. Alternative would be Whitworth - possibly dependent on the age of the meter?

The 8 - 32 UNC tap and die arrived today and I can confirm that the single threaded stud on the back of the Smiths oil pressure gauge is 8 -32 UNC.

I had this issue with my Smiths oil pressure gauge 3ba didn't fit so i bought 2 of the knurled aluminium round nuts and recut them on the original steel studs on the back if the gauge worked a treat.
I know this isn't the engineers route to take but at the time solved a problem.