Old imperial conduit box lid screws

[Aindowsimon]

Any one know the size of the old imperial conduit box screws ?? I don't have callipers. They look to me like 5/16" screws any help appreciated

 

[Julie.]

I have a huge King Dick spanner. Always gets a laugh when I whip it out at parties!

Yes I have had a few King Dicks over the years.


Err hang on, that didn't come out right

Spanners, King Dick spanners!

 

[brianmoooore]

I had the King Dicks out a couple of days ago.
My MF tractor has imperial fasteners on the oily bits, and metric on the bodywork and all the control stuff for the oily bits, and my selection of AF combination spanners are King Dick.

 

[Julie.]

I had the King Dicks out a couple of days ago.
My MF tractor has imperial fasteners on the oily bits, and metric on the bodywork and all the control stuff for the oily bits, and my selection of AF combination spanners are King Dick.

Yeah, all the ones I have are Whitworth (and old Whitworth at that, not modern 1940's sizes).

 

[nicebutdim]

I have a huge King Dick spanner. Always gets a laugh when I whip it out at parties!

All my King Dick spanners are huge. It was only in recent years that I discovered they also came in smaller sizes.

 

[UNG]

There are certainly odd number sizes, from 1 through 11, then 15 (no 13BA for some reason), here is a small selection of my box of BA taps

View attachment 98770

I couldn't find a 11BA, 14BA, 15BA OR 16BA tap in this box, but I am sure I have them somewhere.

And it looks like the Zeus tables making an appearance as well

 

[freddo]

I couldn't find a 11BA, 14BA, 15BA OR 16BA tap in this box, but I am sure I have them somewhere.

16BA must be tiny! I've worked with 12BA and that is small enough!

 

[Petej999]

16BA must be tiny! I've worked with 12BA and that is small enough!

2BA or 4BA not quite sure

 

[pirate]

That is the question....2BA or not 2BA

 

[Julie.]

16BA must be tiny! I've worked with 12BA and that is small enough!

16BA would be 21swg, so around 0.032" ~0.8mm in outside diameter.

Edit

Should have added, BA is based on swg sizes, so 2BA would be a suitable thread for 6swg (0.192") and will cut slightly below this (around 2-4%) to guarantee a proper thread 4BA would be 9swg (0.144") etc.

It was useful because swg would be widely known, and therefore an appropriate BA thread would be known and although they don't equate exactly it's like those snippets:

1/16" ~ 0.0625" ~ 16swg ~ 16BWG ~ 1.6mm

Essentially the old systems all lined up to work together in a practical way.

Of course this only works in imperial measurements, the American things like awg etc don't line up with anything at all.