[AMRadio] Stuck Set Screw

A.R.S. - W5AMI ars.w5ami at gmail.com
Thu Apr 26 10:34:25 EDT 2007

Something you might try if all else fails, and before drilling, is
Reverse Electrolysis.  I have used this technique many times in the
past for restoration of artifacts which were badly oxidized or rusted
with great success.  What you would need for a small knob is the

1) A small metal pan with sides high enough to immerse the knob in liquid.

2) Sodium Carbonate (sodium hydroxide works best, however may be too
caustic for the knob and remove the finish).  Sodium Carbonate aka
"washing power" should do fine.

3) Water

4) Small auto battery charger w/short circuit protection. 3 to 10 amps....

Mix about 1/8 cup of the washing powder with a gallon of water and
fill the pan enough to cover the knob, or at least the metal insert
and set screw.

Attach the positive (+) to the metal pan and the negative lead to the
set screw.  Be sure you don't reverse this, as it will actually rust
the iron even more if you do!  Also make sure the point where the
connection is made with the metal insert does not touch the metal pan!

Turn on the charger and you should see some bubbling action coming
from the set screw.  If not, you either don't have a good connection,
or you need to add some more washing powder.

Let it sit and work for a day or so, but keep an eye on the knob
finish, as I'm not certain what it will do.  The electrical charge
should have no effect on the knob, but the washing powder might, over

The process should break down and dissolve ALL rust, and free the set
screw from the brass.

Again, be sure the (+) is connected to the metal pan and the (-) is
attached to the set screw!  Not sure how you can get a connection to
the set screw, but maybe an allen wrench stuck into it would serve as
a good connector.

Brian / w5ami

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