2BA or not 2BA

[armb]

[Poll #636555]

Comments

[armb.livejournal.com]

An M5 thread is slightly larger than the old imperial 2BA size. A 2BA nut will fit on an M5 screw and rattle slightly but not fall off. An M5 screw (such as the ones that came with the bike rack now on my folding bike) will sort of fit into a 2BA tapped hole (like the one that had the old mudguard mount screwed into it), but only a little way before it jams.
An M5 nut is 8mm, and I have a 8mm spanner on my bike multitool (though mine is the pre-update model), but a 2BA nut is slightly bigger than 8mm across. (An M5 thread is 5mm across the top of the threads).

I have longer 2BA screws in, but the rack was rattling because I hadn't done the nut up tight enough because I didn't have a spanner the right size and it's awkward to fit an adjustable in. (The old screws were only holding the mudguard mount, and no nuts were involved, but the way it is now, there are. (Partly because the bolts that are long enough were too long, so I've put them through from the other side - but I could cut and file them.) Possibly a photo is called for here.)