old screw thread

[333rocky333]

Got to refix some old light box covers.
They have threaded inserts and date back to the late 60's.
Need some more round head machine screws, as lots missing .
2Ba and 5mm are both too tight and 4mm too small.
The pitch of the thread is quite wide like the 2Ba though.
Any ideas what they might be.
Thanks.

 

[ricicle]

Can you not tap them out to 5mm ?

 

[RF Lighting]

It was always 2BA on imperial conduit boxes.

Are you sure it isn't just that the thread has rusted a bit? Might be worth buying a 2BA tap if you've got a few to do, or some self tapping screws if you haven't

 

[flameport]

These:
http://www.a2stainless.co.uk/8-32-UNC-x-1-Socket-Countersunk-Screw_ARDXW.aspx

or these:
http://www.a2stainless.co.uk/10-24-UNC-x-1-Slotted-Round-Head-Screw_A4HRO.aspx

 

[333rocky333]

There not conduit boxes, they have up to 8 screws in each sign box.
I have been tapping them to 2BA but will be nice to just get replacements.
The 5mm tap was too tight and just loosened the crimped in thread things
Think I will try the UNC thread.