Imperial thread nomenclature

[Deadeye]

I bought an old sander and one of the plate mounting machine screws is broken.
The major diameter (learned somehting today) is 1/4" and it's 1/2" long. I got a thread gauge (every day is a school day for newbies) - it's 36 whitworth.

Now, the rub is that I can't seem to find a 36/inch 1/4" diameter bolt for love or money - they're all 20, 28 or 32.
Am I searching for the right thing? Is there a more common nomenclature for the same thing?
Countersunk ideally, but I'd put up with hexagonal heads right now!

 

[novocaine]

Unless it's a steam engine it's pretty unlikely to be a Whitworth thread pitch and more likely to be 1/4" UNC (both have 20tpi and 1.270 pitch).

try these folks.

https://www.westfieldfasteners.co.uk/A2 ... .2500.html

 

[Deadeye]

Hi

Thanks - but it's 36 threads/inch

 

[Deadeye]

I got the diameter wrong though - 5/32.
But it is 36G.
I can get taps that size, but not bolts!

 

[MusicMan]

Looks as if it could be #8-36 UNF.

https://www.accu.co.uk/en/imperial-cap- ... gI_7fD_BwE

 

[Deadeye]

Owwww. My embarassment hurts!
I was deceived by all the other imperial bits I have been playing with.

It's a bog standard M4.
(
Sorry!

 

[novocaine]

Morris and bl did metric bolts with whitworth heads for 30 odd years l, didnt know many others did it too.

Sneaky so and sos.

 

[Deadeye]

Morris and bl did metric bolts with whitworth heads for 30 odd years l, didnt know many others did it too.

Sneaky so and sos.

You're being generous. A simpler explanation is that I'm an idiot.
To be fair, everything I've been playing with recently is ages old so I'm in the habit of using imperial calipers, and 5/32 is v close to 4mm...
Yup, I'm just an idiot...