On 6/4/2010 11:29 PM, Smitty Two wrote:
In ,
wrote:

On Fri, 04 Jun 2010 08:28:30 -0700, Smitty Two
wrote:

In ,
wrote:


Drilling to the root of the thread is only the last resort. In order
to have success with this method you must be even more accurate
with centering the drill. Then you have to cross your fingers that the
remaining bolt thread will come out cleanly and leave 100% of the
original surrounding steel.

It's the first resort in a machine shop.

You don't know what you are talking about.

Sorry, I should have qualified that statement. In the machine shop I've
been working around for 25 years, we always drill out broken
screws/bolts. I don't know what other shops do. Maybe they use
extractors from Sears.

I've taken a valuable assembly to a machine shop on occasion to get
the experts to remove a broken bolt and the machinist would use a
carbide tipped bit like that used to drill concrete, chuck in his
drill press and carefully drill out the hardened broken bolt. I go
to a machine shop when I fear I may damage something when trying to
extract a broken bolt.

TDD