I am posting this on the off-chance it might be useful to someone else with the same problem…
I was asked to have a go at removing a stuck bottom bracket from a titanium frame. The BB was a Miche square taper with alloy cups - the shoulder had been removed from the drive side cup to allow for better chain alignment, not that that makes any difference to removing it.
A LBS had already had a go at it, including trying an air impact wrench, and had stripped the extraction splines on both cups! The owner was ready to write-off the bike so there wasn't much to lose.
I made a drill guide using a pillar drill to drill two accurate holes in an odd lump of metal I had knocking around.
2018-03-07 17.48.33 by
Graham Dore, on Flickr
The large counterbored hole fits snuggly over the square taper of the BB spindle and the small one acts as a guide for a 6mm drill.
This allowed me to drill accurately into the BB shell with a hand held power drill without risk of touching the frame with the drill bit. The red leather welders apron is to fend-off damage to the frame in the event of the drill breaking (which wasn’t necessary).
I tried one hole both sides and used the drill guide tool with a high tensile bolt inserted through it into the cup. I tried to unscrew the cups by turning the drill guide with my monster stilsons – no chance – the bolt sheered both sides.
Having drilled all the way around both cups (turning and re-clamping the drill guide for each hole) I found a piece of tool steel which just fitted tightly through the guide hole on my drill guide. I clamped this to the BB spindle and used it to scrape away the metal between the holes on one side, exposing the bearing.
I drove the innards of the BB out of the open cup with a lump hammer – it was very tight, so I tried to turn it with my monster stilsons in the hope it would unscrew the cup – it didn’t – the innards of the old BB shattered.
I removed the innards of the old BB completely and VERY CAREFULLY cut slits in the remains of both cups with a hacksaw.
After a bit more faffing, repeatedly sawing a bit and then using a punch, I managed to get both cups out without any damage to the frame. Big sigh of relief.