[Boatanchors] BC-223- Fixing a Rotted Pot Metal Casting. Maybe.

[hwhall at compuserve.com]

> ...so wouldn't do for really big defects...

Modelers sometimes fill larger gaps with an adhesive mixed with a filler, sometimes nearly microscopic glass beads or other materials. Usually they are using Superglue type adhesives. Perhaps the Threadlocker could be mixed with metal filings or some of the modeling beads to get a gapfilling adhesive. Just a thought...

Wayne 
WB4OGM


-----Original Message-----
From: David Stinson <arc5 at ix.netcom.com>
To: boatanchors <boatanchors at mailman.qth.net>; milsurplus <milsurplus at mailman.qth.net>; mrca <mrca at mailman.qth.net>
Sent: Fri, Apr 11, 2014 3:11 pm
Subject: [Boatanchors] BC-223- Fixing a Rotted Pot Metal Casting.  Maybe.


Under the bottom-front cover of the BC-233 transmitter,
between the ganged "MO" and "PA" capacitors,
there is a "pot-metal" casting that holds the end
bearing for the tuning shaft
(this photo used with thanks to Dennis, W7QHO).
The green arrow points to the casting:

http://home.netcom.com/~arc5/BC-223/BC223bottom.jpg

There is a bar at the bottom of the casting that connects
between the two capacitor housings.
A "J"-shaped post extends from this bar to hold
 the rear bearing of the tuning shaft.
This casting is "pot metal" and in mine, it was "rotten."
The "J" had broken from the bar and also split
at the inside bend.  Here is a photo of what I found:

http://home.netcom.com/~arc5/BC-223/IMG_3078.JPG

A closer look at the metal rot:

http://home.netcom.com/~arc5/BC-223/IMG_3073.JPG
http://home.netcom.com/~arc5/BC-223/IMG_3074.JPG

These piece were very fragile and crumbly.

Here's the end of the tuning shaft with the pieces
removed:

http://home.netcom.com/~arc5/BC-223/IMG_3072.JPG

A gentleman I know who has repaired hundreds of engine
blocks for a major oil field contractor told me about a
"Locktite" product.  It is a very thin, green liquid that is
designed to be applied to already-mated bolts, nuts and
screws etc.  It "wicks"' into the junction between the
fasteners getting into the smallest spaces and pores
where if forms a hard, glass-like binder between
the two metals.  He said he used this to seal
hair-line cracks and fractures in metals.
Here is the "Permatex" version of this product:

http://home.netcom.com/~arc5/BC-223/IMG_3076.JPG

It's not cheap; this little bottle was $8.
But it only take a couple of drops to work.
The application notes for this
product, in .pdf format. are here:

http://www.permatex.com/component/documents/?view=tds&format=raw&filename=29000.pdf&market=automotive

I infused the "rotten" parts with this product and
let them set over night.  The product worked
as claimed.  I can press and squeeze the pieces with
my fingers without bits crumbling away.  Not likely
to be as strong as "new," but better than what I had
and likely to serve.  Here are close-up photos
of the product cured in the metal cracks:

http://home.netcom.com/~arc5/BC-223/IMG_3080.JPG
http://home.netcom.com/~arc5/BC-223/IMG_3084.JPG

As you can see, the product "wicked" into even the
smallest cracks.  It's speced for filling only up
to 5-thousandths, so wouldn't do for really big defects
but it appears- so far- to be very helpful with bad
pot metal.
I've got the two pieces of the "J" epoxied
and will epoxy it back to the bottom bar this evening.
We'll see how it works out.

GL OM ES 73 DE Dave AB5S

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