Any obscure BB removal suggestions before I go the sledge hammer route??

[geof767]

It's a threaded square taper, and I've gone through all of the normal steps, it's been steeped in penetrating oil for a week, I'm turning towards the front, I have a 5ft "persuader" bar on the end of a spanner with heat and although I got the drive side to turn (almost one full rotation) it was at the cost of the teeth so now there's nothing for the tool to grab.
I thought once it turned at all it would release up but no so I'm guessing there's a lot of internal thread damage anyway.

I don't have access to a pillar drill so I can't go that route.

LBS has already waved the white flag.

The frame is an M2 Stumpy and holds a great deal of sentimental value so it is fairly daunting to take the step of bracing the frame on it's side and belting it with a sledgehammer. If anyone has any magic solutions that don't involve welding (fabricator looked and is pushing the sledge hammer route) I would be very grateful.

 

[WildGoose]

It's a threaded square taper, and I've gone through all of the normal steps, it's been steeped in penetrating oil for a week, I'm turning towards the front, I have a 5ft "persuader" bar on the end of a spanner with heat and although I got the drive side to turn (almost one full rotation) it was at the cost of the teeth so now there's nothing for the tool to grab.
I thought once it turned at all it would release up but no so I'm guessing there's a lot of internal thread damage anyway.

I don't have access to a pillar drill so I can't go that route.

LBS has already waved the white flag.

The frame is an M2 Stumpy and holds a great deal of sentimental value so it is fairly daunting to take the step of bracing the frame on it's side and belting it with a sledgehammer. If anyone has any magic solutions that don't involve welding (fabricator looked and is pushing the sledge hammer route) I would be very grateful.

I know it sounds weird but have you tried boiling water on the outside of the shell and using a plumber freezer spray on the inside it might crack the seal of the parts to loosen it, enough to remove. No idea if it will work but least its better than the sledge hammer. Just a thought , I know only just lol hope you find a way.

 

[Takingabreak]

tacx 4415 bottom bracket tool for next time you need to remove one. The tool locates by screwing into the end of the axle which means it doesn't slip when applying lots of force. Probably too far gone for one to help you this time

 

[bikeworkshop]

Mig-weld a large open spanner head onto the bb - the shock of the welding energy will break the bond, and the spanner will then get it out.

(You'd want to remove the chrome from the spanner first, and grind the coating off the bb shell - someone familiar with welding will know.)

The problem though is that the alloy bb threads might be powder - but then you can use a self tightening bb, or get a new sleeve bonded in.
Simple

 

[awac]

You could try acetone/atf mixture.

“In 2007 "Machinist's Workshop Mag. tm" published information on various penetrating oils including subjective tests of many of the popular penetrants. The following list is the results of their test with the control being the torque in- foot pounds required to remove a nut from a bolt in a "scientifically rusted" environment.
Penetrant ------------------------------------------ Average Load
None ------------------------------------------------ 516 Ft. Lbs.
WD-40 ---------------------------------------------- 238 Ft. Lbs.
PB Blaster ----------------------------------------- 214 Ft. Lbs.
Liquid wrench ------------------------------------ 127 Ft. Lbs.
Kano Kroil ------------------------------------------ 106 Ft. Lbs.
ATF*/Acetone Mix --------------------------------- 53 Ft. Lbs.

ATF= Automatic Transmission Fluid

The ATF/Acetone mix was a "home brewed" mix of 50/50 automatic transmission fluid and acetone which proved to be better than any of the commercial brands of penetrant on a removing a nut rusted onto a bolt. No matter which penetrant is used they all require a period of time to wick down into the threads, but because acetone has an extremely low dynamic viscosity, it's thin, it gets into the threads quicker than the other products with the ATF following shortly behind for lubrication.


This discussion is all over the web, but I took this one from “Britbike forum” (Motorcycles).

I was just typing “weld a spanner” when bike workshop posted! Lol.

 

[bikeworkshop]

Tell you what though - I've tried penetrative oil 1000 times, and the results are... disappointing.

Once you've a build up of oxide and a touch of electrolytic welding (if that's the right phrase) then lube ain't gonna do it.
Can't hurt though.
As long as you don't set it all on fire with the blowtorch...

 

[Woz]

Depending on what the BB* is, it could be dismantled in situ.

You could then insert an hacksaw blade in the void, make one or two cuts and collapse it.

* A steel early UN5x would be painful to saw, but doable. A alloy UN72 would be a piece of cake. Pictures will help.

 

[awac]

Tell you what though - I've tried penetrative oil 1000 times, and the results are... disappointing.

Once you've a build up of oxide and a touch of electrolytic welding (if that's the right phrase) then lube ain't gonna do it.
Can't hurt though.
As long as you don't set it all on fire with the blowtorch...

Generally I agree. I use heat if I can, or in extreme cases of rust drop said item in a bucket of phosphoric acid and come back a day later (don’t try this with alloy). Rust eaten, item free to move.
I have been trying this mix with oils, and it works,but need to get atf (and something really stuck) for a real test. The problem with acetone is you need a good seal to stop it evaporating quickly. It would be interesting if geof767 did try something this solid with acetone/atf to prove if it was that good, after other penetrating fluids had failed?

Isn’t that what blowtorches are for?

 

[benjabbi]

Bolting the tool in so it can't slip and a feck off breaker bar have never failed me but when the teeth have already gone then I've done a couple the @Woz way, if it is a steel cartridge a Tungsten Carbide saw blade makes things slightly more bearable, still takes a while though. A stubborn 'this won't beat me' attitude helps!

 

[Suprachrgd82]

You could try acetone/atf mixture.

“In 2007 "Machinist's Workshop Mag. tm" published information on various penetrating oils including subjective tests of many of the popular penetrants. The following list is the results of their test with the control being the torque in- foot pounds required to remove a nut from a bolt in a "scientifically rusted" environment.
Penetrant ------------------------------------------ Average Load
None ------------------------------------------------ 516 Ft. Lbs.
WD-40 ---------------------------------------------- 238 Ft. Lbs.
PB Blaster ----------------------------------------- 214 Ft. Lbs.
Liquid wrench ------------------------------------ 127 Ft. Lbs.
Kano Kroil ------------------------------------------ 106 Ft. Lbs.
ATF*/Acetone Mix --------------------------------- 53 Ft. Lbs.

ATF= Automatic Transmission Fluid

The ATF/Acetone mix was a "home brewed" mix of 50/50 automatic transmission fluid and acetone which proved to be better than any of the commercial brands of penetrant on a removing a nut rusted onto a bolt. No matter which penetrant is used they all require a period of time to wick down into the threads, but because acetone has an extremely low dynamic viscosity, it's thin, it gets into the threads quicker than the other products with the ATF following shortly behind for lubrication.


This discussion is all over the web, but I took this one from “Britbike forum” (Motorcycles).

I was just typing “weld a spanner” when bike workshop posted! Lol.

When you know, you know. The ATF mix is magic.


Geof767, is it a splined or cup style?