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Rather than driving a screw into the stripped screw or
completely drilling it out, it would be much easier and
faster
to have this special bit. It would consist of a heatable
(by
using a separate interface) bit of carbon steel in the
center
surrounded by an alloy with a higher melting point.
The
user
would heat up the center of the bit and then place it onto
the
stripped screw and wait five minutes for it to bond.
Then the
user would remove the bonded bit.
Separate interface includes a laser to remove the screw
and a molten metal feed to replace lost metal.
Screw Extractors
http://www.sears.co...code=35-151069681-2
Easier "easier unstripping tool". Just use your power screwdriver in reverse and these extractors will bite into the metal (or plastic, or whathaveyou) to back your stripped screw head out without harming the work piece. [jurist, Jan 06 2014]
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Annotation:
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All good unless the stripped screw is in something
(like wood or plastic) that can't take the heat. |
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Or the screw is aluminum, or nylon, or a grade of
steel that doesn't weld well. Also, the amount of
weld contact you're going to get in this, for most
screws, won't be strong enough to produce
sufficient loaded cross section to not pull apart if
the screw is actually jammed (the most likely
cause of stripping). |
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You'd probably be better off with an adhesive, on
of the loctite "bond to anything" varieties (they
don't, but they're pretty good). Either way, you're
going to have to be very careful you don't slip off
the screw head during the bonding period. |
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I've sometimes welded a bar to the head of a rusted-
in bolt, to give the leverage needed to shift it. But I
suspect the heat of the welding helped to loosen
the bolt. |
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Otherwise, it seems easier to drill into the screw and
use one of those reverse-threaded thingies to tap
into it and extract it. |
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In nearly every hot-welding method the weld material (the
metal added during the welding process) must match the
base material, so each single-use unit would have to be
specific to the type and brand of screw it is used to
remove. You're not going to get away with just 'high-carbon
steel' (which in itself is a general description, not a specific
material). |
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There are very few screws (other than machine screws,
which to the lay eye look like small bolts) that would take
a good weld without cleaning. Almost all screws made for
wood or drywall are coated or finished for corrosion
resistance, and likewise nearly all are heat treated--the
heat of whatever unspecified method the author has in
mind would 'undo' this process, weakening the head and
upper shank of the screw and virtually guaranteeing a
shear-off. |
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Also, the heat required to make a good weld (in excess of
2500 degrees F for steel, 1800-ish for aluminium) would
char the wood around the screw hole, and it would be
difficult to contain the molten slag and flux materials that
constitute what welders call 'spatter'; welding is not a
gentle process. |
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I could go down to my shop and test this idea without too
much effort, but I don't need to. I'm certain it wouldn't
work as advertised. |
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There are tap burners, basically a portable EDM, they use to remove broken taps. The companies that make those burners might have a product you could adapt for welding on. The EDM could remove the coating. |
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A set of of sharp and varied size screw drivers will help avoid stripped screws. Some of the electric screw drivers don't give you enough control over speed and torque and can strip dozen of screws before you can adapt. |
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Plastic brass aluminum steel - so many screws, so little time. |
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If the screw won't turn, try rotating the workpiece
instead. |
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