Electrical switch fixing screw thread

[RogerS]

Does anyone know where I can get some nuts from that fit the screws used to fix sockets/switches to the pattresses? The thread is larger than M3 but not as large as M4...if there was such a thing as M3.5 then that would probably be it.

But....I have a sneaky feeling that the thread is non-metric.

Many thanks

Roger

 

[DaveL]

Roger,

How about M3.5 as listed in the Screwfix catalogue, here as Electrical Screws.

 

[johnelliott]

It's actually the nuts that Roger wants. I reckon the best bet would be to get an M3.5 tap (if you can) and run it through some M3 nuts
John

 

[jasonB]

M3.5 nuts here in small quantities.

If you want to use johns method I can point you in the right direction for Taps.

Jason

 

[DaveL]

I was trying to point out that Roger was indeed looking for M3.5 which he seemed doubtful of its use. I had no idea where to get the nuts just the size he needed. Sorry if I miss lead anyone.

 

[RogerS]

Thanks everyone. So the consensus seems to be that they are M3.5 ?

Roger

 

[Midnight]

ummmmm.......actually they're not M3.5... I think you'll find they're closer to 3BA...

good auld fasioned British Standards... Ahem....

 

[DaveL]

Mike,

They used to be 4BA, M3.5 is very close. Too close if you mix old and new fittings/boxes the screws just go in and then get tight, one quick twist of the wrist will fix that as the thread strips. :roll:

 

[CHJ]

ummmmm.......actually they're not M3.5... I think you'll find they're closer to 3BA...

good auld fasioned British Standards... Ahem....

I think you will find that old ones (up until the 60's) were 6BA, latest incarnation is M3.5, hence why replacement fittings using new supplied screws in old patrices result in messed up/stripped/jambed screws.

Most electrical supply factors will have M3.5 taps for 'adjusting' the slightly smaller 6BA hole in old patrices to suit.

 

[Anonymous]

'tis M3.5 on any new sockets, light switches etc.

 

[Midnight]

I stand corrected......

 

[RogerS]

Jason

Please can you let me know where to get the M3.5 tap from?

Many thanks...Roger

 

[jasonB]

Try these, it's the metric course thread you want, you will also need a 2.9mm tapping drill.

http://www.engineerstoolroom.co.uk/dies ... %20Threads

http://www.tapdie.com/html/metric_taps_ ... c__ta.html

Jason

 

[Alf]

Axminster do them too.

Cheers, Alf