On Sun, 3 Aug 2014 23:32:19 -0400, "Mike Marlow"
wrote:

JAS wrote:
And stuck bolts don't care about theoretical physics. Have you ever
had to remove any REALLY stuck bolts??

I have a stuck bolt right now holding a lawnmower blade on that
belongs to my neighbor lady, removed two of the blades but the third
one will not budge. I have used an impact wrench but someone had
rounded the bolt before and even tapping a smaller fraction size on
it will not grab good enough. Tried vice grips and pipe wrench--what
next, maybe heat. I am afraid it will break and then the mower will
be toast, it is an old John Deere her husband had before passing
away. Any ideas?

Ugh! been there done that. You're kinda screwed at this point so why not
go for broke? I'd put heat to it but as always with heat - pay attention
and don't just put a ton of heat on there that you really don't need. Is it
a bolt or a nut? If it's a nut, then heat just the nut to the point that
it's wanting to turn red. Then get on it with your gun or your wrench.
Or... with your wench... If it's a bolt then, be careful - you just don't
have a lot of structural material to work with there. Heat up the head of
the bolt to red hot and hope you achieve enough heat transfer to allow you
to back it out. You can try products like breakfree or pb blaster - and they
do work - just not all the time. It's kind of hit and miss with those.
Water often works every bit as well as the penetrant. Quenching with
water shocks the rust criystals and makes them real fine - and water
mixed with the ultrafine rust actually acts as a lubricant. Oil based
penetrants have a tendancy to just boil off or burn when you squirt
them on something red hot, and water removes more heat faster.