What thread is this?

[neksmerj]

In front of me is a screw and a hex stand-off, and I'm buggered if I can ID the thread. Been through the ZEUS reference tables, Unbrako catalogue, and the web using the 32 TPI as reference. There are a number of thread types with 32 TPI, but can't get a match on the OD.

OD-3.36mm
ID-2.83mm (inside measurement of stand-off)
Pitch-32 TPI

The closest I can come up with is
thread size-#6
Form-32 UNC
OD-3.5mm

I suspect this is not it, as generally screws measure under the nominal diameter. 3.5mm is considerably bigger than 3.36mm.

It has come out of a piece of electrical equipment, do sparkies have their own special screws?

Your assistance is needed.

Ken

[Calm]

Here is a thread chart and i thnk you are right with what you think.

http://www.classicfasteners.com.au/T...a/THREADCH.PDF

Converted to metric 32TPI is 0.794 or rounded to 0.8

Both charts are there and the only one close is 6G 32 unc

Hope this helps

cheers

[neksmerj]

Well I'll be buttered on both sides.

Have just discovered that sparkies use M3.5 screws for electrical fittings.

Can a kind member please confirm the thread pitch. I'm hoping it's around 0.8mm.

As "Calm" mentions above, 32 TPI equates to 0.794mm.

If that's so, I'm in business.

Ken

[pipeclay]

Ken have you checked with a thread gauage for pitch or TPI,3.5mm coarse pitch is .6, 3.5 mm fine pitch is .35.

The UNC size you gave falls in the major,minor OD range for 6-32 UNC.( max OD 3.47mm , min OD 3.32mm)

[Metal Head]

Ken have you checked with a thread gauage for pitch or TPI,3.5mm coarse pitch is .6, 3.5 mm fine pitch is .35.

The UNC size you gave falls in the major,minor OD range for 6-32 UNC.( max OD 3.47mm , min OD 3.32mm)

From the info given, I would go with your answer pipeclay (6-32 UNC)

[Ashore]

Have just discovered that sparkies use M3.5 screws for electrical fittings.

Can a kind member please confirm the thread pitch. I'm hoping it's around 0.8mm.

Sorry mate M3.5 is 0.6

[Fossil]

Post deleted because I had too much wine and thought I new it all. Posted a BS answer, so hence the delete.

[joe greiner]

It's either a metric thread OR an Imperial thread. Can't be both.

32tpi corresponds to 0.794mm pitch. 0.8mm doesn't show up until M5, which is too big.

I'd bet on 6-32UNC. For Class 2A, the OD range is 0.1312 - 0.1372 inches (3.33-3.48mm). For Class 3A, the OD range is 0.1320 - 0.1380 inches (3.35-3.50mm).

Joe

[neksmerj]

Seems I was on the ball in the first place.

6-32UNC it is.

Will take what I have to an industrial fastener outlet, and do a physical match-up.

Least now I have a good starting place.

Thanks guys for you're input.

Fossil, I'm about to join you with a nice cold glass of "medicine", so you won't feel alone.

Ken

[DavidG]

We used to use BA thread for electronics. (Back a long time ago )
4 BA and 6BA come to mind as well used.

[Metal Head]

We used to use BA thread for electronics. (Back a long time ago )
4 BA and 6BA come to mind as well used.

It doesn't look like the case here David.