Jim Flanagan wrote:
In article ,
says...
On Tue, 20 Jan 2004 23:18:32 GMT, Jim Flanagan
wrote:

Hello..
I have an aluminum radio chassis that I am in the process of
restoring. By restoring, I mean that I have dissassembled the
radio to the bare natural aluminum chassis and am polishing out
most of the scratches, etc. On the back of the chassis, there are
two holes approx #10 screw size that were drilled by a previous
owner for no telling what. Anyway, I need some tips on how to
patch these holes in an attempt to restore the original 'look' of
this chassis as best I can. Here are the options that I have
thought of:

Place a screw/nut into the hole and live with it.

Use a press in stud. Do they make aluminum studs?

Have someone attempt to weld up the hole with aluminum and
grind/feather the surrounding aluminum.

I've considered, epoxing a piece of Al disk to the back of hole on
the inside of the chassis. Cutting another disk of Al which would
fit the hole as best as possible and epoxing. Sanding and
feathering would then follow.

What are your opinions as to how and approach this? Since I want
the natural aluminum look, painting is not an option. Thanks for
any advice you would be willing to share.

Jim

Greetings Jim,
This is a little work but will leave an undetectable repair in bare
aluminum. Go to the hardware store or hobby shop and get a length of
aluminum rod that is close to the same size as the hole. If it
doesn't fit close, that is within about the thickness of a hair or
two, then get the next size up and a drill the same size. Drill out
the hole carefully so it is round. Then hammer lightly on the end of
that rod you bought. Just enough to swell it about 1/64" to 1/32"
right at the end. Hacksaw off this end so it that when pressed into
the hole it protrudes about 1/32". Clean both pieces so there is no
oil on either. Sand lightly the plug before installing. Now, put an
anvil of some sort under the swelled end. A good one would be a flat
end punch about twice the diameter of the hole held in a vice. Use
another flat ended punch placed on the sawed end of the punch and
give it a good whack. This will swell the rivet in the hole and
expand the side you are working on. It is OK to hit it more to get
it really tight but don't over do it. The hammering is going to
harden the aluminum and eventually crack it. After the rivet is
tight you can file and sand it flush. If the aluminum is not
anodized it will not show. If you clear coat it will never show. If
left un-coated it will probably eventually

This sounds like something that I can do.. Thanks Eric. I will give
it a try. Take care..

Jim

One of my mechanics was telling me today that at Grumman they used to cool
aluminum plugs in liquid nitrogen, stick them in the hole and machine the
excess off. You could not tell where the hole was after the process was
done. He did not do the process himself but witnessed it being done as a
repair for misdrilled/oversized holes.