I know what the things I want look like, they’re M12 x 50mm threaded studs, but with spanner flats in the middle so they can be tightened up.

Please put me out of my misery and tell me what they’re called 😀

Like this?

No idea

Flugelbinders?

Do you mean double ended stud or do you mean with opposing threads so that turning the flats brings two parts together/apart?

Scotroutes – exactly like that!

Onzadog – M12 RH both ends. It’s to join two tubes together, I’m putting M12 rivnuts into the ends of the tubes, and want the stud to be captive in one, and then thread into the other.

If you don’t recess the rivnuts, won’t you have the flat part of the double-ended screw/stud/bolt/bar between the two tubes?

Use star fangled nuts so they’re recessed to hide the flats 🙂

threaded hexagonal bar AKA THB 😉

The tubes don’t necessarily need to end up flush – and the thread on the rivnut is recessed by 10mm anyway.

I suppose I could just weld a nut in the middle of a threaded rod…

Hex shoulder double stud should pop up a few results but why do you need the nut in the middle?

You could screw one end of a normal stud in using the double-nut technique – maybe loctite it in place- then just screw the other tube onto it.

Surely a stud with flat bits is called a Burt Reynolds?

Isn’t it Dave?

Hex collar stud or double ended stud

You could screw one end of a normal stud in using the double-nut technique – maybe loctite it in place- then just screw the other tube onto it.

It’s going to be screwed and unscrewed, I want the stud to stay put – I could drill and pin it I suppose, but trying to simplify things if I can.

They’re called Grollings.

HTH