Contribution by rustie@earthlink.net

Replacing Broken Screws or Taps in Aluminium parts

Have you guys ever had a broken screw - or worse - a broken tap in an
aluminum case or other aluminum part??? Well, if you can get the part
disassembled to a small enough size (or come up with a big enough pan!)
here is a way to remove it: 


If at first, a broken tap or screw cannot be removed by "forced
unscrewing", I have a foolproof but slightly time consuming removal
method. EVERYBODY, BE SURE TO COPY THIS TO YOUR FILES: This method is
ONLY for NON-FERROUS METALS (ie: the part you need to remove a ferrous
screw "FROM" MUST BE non-ferrous): First, get either a glass or
aluminum container large enough to hold your part (NO FERROUS PANS!).
Purchase some "ALUMINUM SULFATE" (Al2SO4) at a chemical supply store (I
use a "Student Science Supply" in my area - its cheap!). First, clean
off all oils and grease from your part with acetone. Next, determine
how much water is needed to cover your part by at least 1" in your
chosen bowl or aluminum pan. Heat this water to 130-150F in your bowl
or pan. You will need to maintain the above temps for several hours, so
put it on a stove or hot plate and be sure to add water as it
evaporates, maintaining the SAME water level that you started with.
Stir a small continuous amount of Aluminum Sulfate into the HEATED
water using a plastic, wooden or aluminum cooking spoon (without the
part in the bowl of course!) until you have a "saturated solution" (ie:
until no more Aluminum Sulfate will dissolve - it just falls to the
bottom of the bowl). At this point, put your part into the heated
"solution" - DO NOT COVER, but turn on a fan if indoors (there is an
odor and some fumes, but nothing terribly toxic - just don't drink the
cooled solution and clean up any splatter with water and should the
solution come in contact with your skin, again just wash with water).
The tool will dissolve from the part by a chemical reaction similar to
using a strong acid to do the same job. It may take several hours to
work depending on the size of the tool or screw you want removed. Keep
an eye on the process because the stuck tool may eventually become
small enough to fall out! Good 

Luck - and copy this info! Rustie-----

Rob Koopman ( Rob.Koopman@inter.NL.net ) ^{RG500 Index}