Trying to remove an Italian bottom bracket fixed cup the from a vintage Bianchi, but the little bastard doesn't want to budge. I've tried the Sheldon Brown method with the 1/2" bolt, nut and washers but it appears to have caved in the center of the cup slightly (RIP Dura Ace cup) and snapped the 1/2" bolt. And yes, I'm rotating counter clockwise to loosen.

Grade 8 bolt?
Penetrating oil liberally applied multiple times starting a couple days before attempted removal?
I lay the bike on its side, cup on the bottom.
Squirt PO into the shell from the top and let it run down the sides of the shell to where you really want it.

Careful surgery with a grinder? I'm guessing a "Dremel"-type tool would be too weak/delicate to ever get the job done.

Probably not Grade 8.. just one I grabbed from HD. I'll grab a Grade 8, in a 5/8" this time. and some penetrating oil and give it another ​​​​go..I just used WD-40 this time

WD-40 is for sissies; actually it is for drying ignition wires, originally, Water Displacer recipe #40.
Get some REAL penetrating oil, Kano Kroil is the best, PB Blaster is second best. Spray it on, tap with a hammer (the vibrations help it penetrate), spray more and WAIT for it to work. Heating the shell with a hair dryer may also help during removal.

I think we’ve been doing this wrong for a long time. And, given that you are at least the second person to have crushed a fixed cup, I think that Saint Brown’s method doesn’t work as well as advertised. I would suggest a better way that I wrote up for my local co-op. One caveat is to use penetrating oil like others have suggested.
I, like most everyone, have been taught to remove the adjustable cup first, followed by the fixed cup. We avoid removing the fixed cup because it can be difficult to remove. I propose to stand the procedure on its head. Remove the fixed cup first since it is the hardest one and the wrench needs the most stabilization. The spindle can be used in the same manner as the threaded axle in the above tool but it will allow the wrench to turn with the cup so that the tool doesn’t even need to be removed to completely remove the fixed cup.
Since there are 2 types of spindle, the procedure and fastener used will depend on which spindle is present. The nut or bolt used on the spindle can be used to hold everything in place.
Tool Assembly
The parts for the nutted spindle needed are shown here

A large fender washer, an adjustable cup, and the spindle nut are needed. Another washer may be needed to get the spacing right. The order of assembly follows







From above it should look like this

Turn the wrench as usual. If more leverage is needed, a cheater bar is needed.

For bolted spindles, the order of assembly is the same except a bolt is needed.



This method is much easier to use than other methods. The spindle stabilizes the wrench and turns with it much like a cartridge bearing does. It makes it easier to remove the fixed cup and results in less blood spilled.

cyccommute , Mr Brown needs to update the "bible" to include your method

Using the proper tool often makes the job go better, your refinement seems like a great idea.

Worst case scenario weld a large nut to it then wrench it out
​​​​​​this if the Sheldon method won't work or I have rounded the edges by using the wrong tool and am relaxing it anyway

Yo, cyccommute! Great idea.

Excellent! I'll try it the next time I have a chance. I usually clamp the flats in a bench vise and use the frame for leverage.

Thanks, all.

good grade helps also try freeze off.....combo of penetrating oil and thermal (cold) shock, and leverage

Got it! 2 days of soaking in PB blaster and the grade 8 hardware did the trick.

Kind of like in post #2

Glad to hear it. I was about to suggest to make sure that the frame isn't vintage enough that the frame is Italian threaded, because then both BB cups would be right-hand threaded.