hi,
im tarting up an old steel frame of reasonable good quality but have realised the lower headset cup is loose.its been moving about combined with a little corrosion so is no longer a tight fit.its a steel frame and not worth lots of money investing in it but i wondered if i could use a vice to perhaps nip the headset tube or the cup itself to make it slightly of round and then it would hopefully grip a little better?
anyone else doe this or any other ideas?
cheers!

If you do that, then the bearings won’t like it. Araldite is the second-best answer assuming you don’t have access to a knurling tool.

Check the head tube hasn’t flared or cracked, though.

you can manually knurl it with a centre punch, this is what I did to fix a loose crown race.

Otherwise a wrap or two of PTFE tape?

FSA Pig headset has deeper insertion and might hit a better part of your head tube. Needed to do this on an old Kona Cindercone frame I had as it was slightly stretched….

Coke can.

i’d probably try a coke can shim first.

Loctite bearing fit.
Or if more filler required, that two-part metal filler thinned with meths.

Loctite bearing fit stuff and some centre punching to give it something to grip too, would be best of both.

1. Oversize headset cups are available from Chris King.

2. Or knurl the headset with one of these.

3. But bearing retaining compound would be a LOT cheaper!

+1 loctite retaining compound. Mega strong stuff.

so how do you knurl it with a centre punch?.dent the tube externally to create lumps internally?

I’ve used Araldite Rapid Steel adhsive for this exact problem. Worked perectly. Headset cup can still beremoved from frame (will probably need sanding to remove the adhesive but not a big issue). Bearing rreataining compund might work, but if the gap is too much, it might not be as effective as the above.

so how do you knurl it with a centre punch?.dent the tube externally to create lumps internally?

No, punch on the inside. The pock-mark will have a raised ridge around the edge like a crater.

I’d try bearing-fit first though. Easier.

The Stein thing is what I use. Fantastic bit of kit, though perhaps a bit pricey for a one-off job 😉

Done it with a coke can shim.