What thread are these braze-ons

[Dodge2015]

I am rebuilding a British 1950s bike. I am looking for new replacement bolts for the following components:
1) Headlamp boss on front forks.
2) Mudguard and carrier eyes on dropouts.
3) Campag down tube studs.

Anyone out there know what threads these should be? I have been through my misc bolts tin and can find nothing that is an easy fit. I don't want to strip the threads forcing an incorrect bolt in.

 

[531brazed]

2ba for mudguard eyes
Not 5mm but that can be forced in
good conversion table here
http://www.inox.ie/Conversion-&-Thread-Tables.pdf

( nerd online for thread equivalents etc, should cure insomnia )

 

[keithglos]

Re:

Lamp boss 5/16 x 26 Mudguards 3/16 but 2 BA was used, (not Raleigh)
Campagnolo 5mm.

Keith

 

[Dodge2015]

Re:

Thanks - very helpful - just what I needed to know.
Now another one.

What thread are the small grease nipple holes that are in the BB and headset lugs? The respray has left them a bit clogged.

 

[Martin Rattler]

Re:

I think that the grease nipples are generally 2BA as well.

 

[Steelframeman]

Along with small threads like BA there are also B.S. Fine & B.S. Whitworth.

Interesting the tapping drill for 2BA is the same as 3/16" B.S. Fine.

If its a nut & bolt then its what you can find, but if its anything tapped allow some caution.