ARWadsworth wrote:

"Dave" wrote in message
...
ARWadsworth wrote:

"Dave" wrote in message
20 to 25 years ago, I was given a 3.5 mm tap for back boxes,

Not much use in a 4BA hole -)

Ah, I see what you mean. My big mistake. :-(

Dave

I also have a 4BA tap and some 4BA bolts. Guess what I use to fit
sockets to back boxes where the 3.5 thread is totally knackered?

Do 4 BA bolts/screws have the correct countersink angle for fitting
sockets? If so, what is it? It's something I have never looked at.

Dave