[TheForge] followup on holes in saw blade- broken bolts andleft handed drills

[Jerry Frost]

Yeah, cutting a bolt out of a hole with a torch without damaging the tapped 
threads can be done but it takes a lot of practice and not a little luck. 
Torching a nut off a bolt without damaging the bolt's threads is easy peasy 
by comparison. Torching a simple steel bolt out of a casting is the easiest 
as cast iron doesnt torch cut easily so the threads survive better.

Successfully torching a broken bolt out depends on some variables, the main 
ones, after the skill of the person holding the torch of course, being: 
depth of the bolt, diameter of the bolt and composition of the bolt. Believe 
me it's just Soooo much easier to torch out a plain high carbon 1 1/2" bolt 
that's only in half an inch than it is to attempt torching out a 3/8" 
Stainless Steel bolt that's in 1" or more. Former is darned easy, latter is 
darned near impossible.

If you use an oxy propane torch you can pierce a hole, let it cool and chase 
it out with a HS drill bit. Use oxy acet and it'll impart enough carbon to 
make it necessary to use at least a Cobalt or better bit. I have an All 
States Oxy Propane torch and can attest from personal experience that you 
can either drill out pierced holes or torch cut a piece and chuck it up on a 
lathe, mill, etc. and use HS tooling without a problem. The downside is the 
oxy propane torch will happily cut several layers of steel simultaneously 
making the old cut the nut off the bolt without damaging the threads trick 
really darned near impossible.

Jer
-------------------------
If it ain't forged
It ain't real
wrought iron is
The Frostworks



----- Original Message ----- 
From: "Andy Gladish" <gladish at cablerocket.com>
To: "Blacksmithing List Sponsored by ABANA" <theforge at mailman.qth.net>
Sent: Saturday, May 15, 2010 6:30 AM
Subject: Re: [TheForge] followup on holes in saw blade- broken bolts andleft 
handed drills


> I've heard that if a bolt is broken off in a cast iron casting, you can 
> take
> a torch and blow it out, enough to redrill and tap.
> Always wondered if that was theory or if it really works- tried it once 
> and
> wasn't successful.
> Andy
>