From: okunewck@psuvax1.cs.psu.edu (Phil OKunewick)
Subject: Re: How to remove cross-threaded bolt...?
Organization: Random, at best
Distribution: usa
Date: Fri, 29 Jan 1993 05:04:34 GMT

mcovingt@athena.cs.uga.edu (Michael A. Covington) writes:
>Today I bought a small used circular saw very cheaply...
>...The blade is slightly off-center and the bolt that holds it cannot be
>removed.  My best guess is that the bolt is in fact cross-threaded...
>
>This saw isn't valuable enough to spend money on.  But if I can get that
>bolt out and repair the threads myself, it would be worthwhile.  What should
>I do next?

   It would be extremely difficult to cross-thread the proper bolt
into a circular saw enough so that the blade can still be tightened.
Try to figure out just what the former owner was thinking when he
mucked the saw up.

   You may find that some bozo put a wrong bolt in, possibly with
different threads.  They might have even glued it in (lock-tite?).
It's very possible that the former owner used extreme measures to keep
the blade from stopping - is the spring-washer missing from the bolt
head?  Maybe they even put a blade on the shaft with too small of a
center hole, and it actually is riding on the bolt threads.  Look
behind the blade and see if you can see a shoulder on the shaft.

   If you can find the person you bought it from, explain that you are
perfectly willing to keep the saw for what you paid for it, but you'd
like a clue about the history of this problem.  If it is glued in,
then the appropriate solvent may soak in enough to loosen it.

   If you are not overly fond of the circular saw, you can try methods
that may do further damage.  This opens a whole bunch of possibilities.
Knowing that a perfectly good used circular saw can be bought at a
junk shop for between $5 and $25, the very worst you can do is destroy
this one and have gobs of fun in the process.

   If you can't loosen the bolt, try tightening it.  This may break it
loose so that it might come out.

   Next - one of the easiest way to loosen jammed threads is to treat
the bolt like a nail and hammer it into the shaft a bit.  Don't brace
the saw - the mass of the blade and armature should be enough to
resist the blow of the hammer, especially if the hammer has about the
same or less mass than the shaft.  Don't be afraid to be persuasive -
if the bolt head ain't dentin' then you ain't tryin'.  After a few
blows you may have deformed the frozen surfaces enough to loosen it.

   Likewise, the saw may be willing to do the work for you.  Run the
saw very abusively on junk hardwood.  Then try loosening it again.  I
had a frozen driveshaft yoke spline on my Jeep - I broke a couple $35
gear pullers trying to pull it off.  So I just put the locking nut
back on but one turn loose, took it 4-wheeling for a day, and tried
again.  The yoke popped right off.

   The next choice is to decide what will live and what will die.
Destroy the blade with various metal-cutting impliments of
destruction, and see if you can get a better grip on the problem.  You
might choose to destroy the bolt too, a little at a time.  If you're
really careful about it, you'll be able to spiral out the remains of
the bolt threads.  This will take a while and a lot of patience.


   You've got nothing to lose, and disassembling something like this
can be as rewarding as solving Rubik's Cube.  As a last resort, pack
the saw full of some explosive substance and set it off from a safe
distance.  This will not leave you with an operational saw, but it'll
be a lot of fun anyway.

   Let us know what happens.