BB shell too tight for sealed bearing

Hi Folks, my little problem is this,

I have a late 80's steel frame, which I'm building up with mostly modern stuff. I've bought a nice campag triple chainset and sealed bb.

Trouble is, the seat tube protrudes a little too far into the space of the bb shell. when you screw in the drive-side sealed bb, the shell of the bb touches the ends of the tube, and is pushed off-centre.

Result, you can't screw in the bb more than about half a turn.

I have a sealed bb in my other bike (slightly older) and it's no problem. Seems like this one was just made with the tolerances a bit tight.

Nice lad at the bike shope chased out the threads, so it ain't that I know. And he tried a shimano bb with the same problem. So it seems like they are a standard diameter.

Have sealed BBs got fatter since they first came out?
Is there a make of BB which is recognised among the cognoscenti for its special slimness?
Worst case scenario, can you still get hold of non-sealed bottom brackets (with campag axles)?

Or am I better off trying to grind down the protruding tubes with a little dremel or similar - being careful to leave the threads intact. Hmm steel tubes; could be 1-2 mm I need - might be a big job.

If there's anyone out there who's run into this I'd be v grateful for advice

all the best

Moojohn

Looks like it was designed for a non sealed cartridge BB. Isn't there a modern open bearing BB you can use? I'd dremel the tube...

I dremel'd the tube. Bosch do some nice little grinding shapes which go in a normal electric drill.

I made sure I had the frame firmly fixed, and had a support for the drill to rest on as I held it in my hands. This was because I was worried that the dremel would bounce around inside the bb shell and trash the threads.

No such problem though. Took a few mins to take off 1-2mm where it was in the way.

sealed bb is now in. cool.

Thanks Fedster

If you're going for a modern triple, you could go external bearing if all else fails...

Doh, sorted. Never mind.

That was what the guy at the lbs suggested: with just the axle inside the bb, there shouldn't be much problem with clearances. Slightly ironically, I'd already sprung for a Campag triple with a square taper axle; on the basis that the bb had been made long before outboard bearings had been thought of and I couldn't be sure they'd fit properly onto the shell...