wrote:
Thanks to all in the group for all the great advice and generous offers
to help. It's incredible how helpful the metalworking community has
been.

I have placed my order for conductive epoxy as I see this as the least
risky and least destructive means of getting a repair. I will also try
to use some silver/tin solder and see if this works better than the
lead based solder I've been using.

I can't tell what the posts are made of. Looks like a silver metal with
a gold plate.

In the long term I will also continue to slowly dremel away epoxy to
get to the post. When I get the replacement I'll upload a pic. I'm sure
that there is more post to work with since it broke off within the wall
of the speaker. Maybe if I'm careful and lucky with the dremel I'll be
able to expose enough threads to work with. Exposing enough post to cut
and then join ends together with a threaded sleeve sounds like a great
long term solution.

Any tips on what type of dremel head will cut epoxy but not damage the
post? Should I try to use any solvents when I get really close to the
post?


I can't think of a rotating cutter which would guarantee your not
damaging the remaining part of the post if it touched it, but have you
tried "thermally excavating" the epoxy with a hot soldering iron tip?
Something around 3/16" diameter with a chisel shaped end ought to do it
if you dig carefully.

I do hope you get lucky and you find you can expose enough of the
threaded portion. Judging from the 4-40 setscrew in your photo, I'd
guess that the thread on the broken part (If it's US made) is likely to
be 6-32, in which case the chances of drilling and tapping it for
anything which could give you much strength aren't slim and none, and
Slim rode out of town yesterday. You'd be far better off using Don's
suggested threaded sleeve, once you identify just what the thread specs are.

I wouldn't recommend using chemicals to clean off the post, I just don't
know what the long term effects might be. You could probably get most of
the epoxy of the threaded part just by poking at it with a small sharp
tool, and if there is stuff left in the threads you could probably make
a small diameter erzats "die" to clean it up by taking a matching
threaded standoff (see below) and hacksawing a slot about 1/8" deep
across the diameter on one end.

You could probably buy a "reddy maid" brass standoff from one of many
places like this:

http://www.keyelco.com/products/specs/spec17.asp

And you could shorten a long one easily enought if you needed too, but
it's probably easier just to let one of us make one out of brass for you
and pop it in the mail once the thread specs and length are known.
That's only "the work of a moment" for Don, or even me, and (speaking
for myself) the satisfaction of knowing you helped somebody duck a
horrificly expensive commercial repair job is ample reward.

HTH,

Jeff

--
Jeffry Wisnia

(W1BSV + Brass Rat '57 EE)

"Truth exists; only falsehood has to be invented."