My solution to a bad pot metal situation

[Mr Grumpy]

Hi all,

I just came up from the workshop and thought I'd document and share with you what I was up to tonight.
It's basically my solution to a broken Brunswick tone arm. Now I know some of you may not like
my method and I may not be doing things 'correctly' (it's always a bad sign when you quote the word 'correctly'), but here it is, in all it's monstrosity.

By the way, I don't recommend ANYONE try this unless they're in a well ventilated area and/or have an
extra tone arm to replace the one you're about to butcher.

I start with the broken end of the tone arm. It's difficult to see in this picture but the broken off little nub is actually several little nubs JB welded together. I tried the JB weld several times but it would always break with the extra movement of turning or pivoting the Ultona reproducer.

Second picture is me grinding away a piece of ½ inch copper plumbing pipe. The idea is to use it as a sleeve inside the tone arm and then solder the tone arm pieces together to the copper.
God I hope this works!! (I already know how it turns out but I don't wanna spoil it for you).

Then I slide the sleeve into the tone arm...

And solder...
Now, I just want to pause a minute and clarify that soldering pot metal is NOTHING like soldering copper. I used a propane torch but you really can't heat the pot metal as it instantly starts to bubble, melt, and give off fumes that I'm sure will catch up to me one day.
You almost have to heat the solder with the torch until it softens slightly then place it on the
area to solder and heat the entire area quickly. Come to think of it, I wonder if a soldering Iron would have worked?
But anyway, it wasn't as straight as I would have liked it to be...

Then I added the cap piece and all it's little broken off buddies to the copper.

Then soldered again...

and sanded it smooth...

In the next week or so I'll use some Alcad II to respray the gold on the repair and voila!!
So far it's holding up pretty good!

Hope you enjoyed.

[ImperialGuardsman]

Hey, if it was already broken you might as well. Sometimes I worry about causing "more damage," but broken is broken.

I'd like to see how it holds up.

[AllWoundUp]

Excellent job, looks like you saved it from the scrap heap! There's a low temperature solder called "Tix" that melts at 275 degrees. Works well for stuff that can't stand a lot of heat.

Here's a source:

http://www.micromark.com/tix-solder-pkg ... ,6707.html

[alang]

Great idea. Keep us posted. BTW: there is also a product called "SolderIt for pot metal".
Thanks
Andreas

[Henry]

Excellent job, looks like you saved it from the scrap heap! There's a low temperature solder called "Tix" that melts at 275 degrees. Works well for stuff that can't stand a lot of heat.

Here's a source:

http://www.micromark.com/tix-solder-pkg ... ,6707.html

Thanks for the link; that's good to know. But will it stand up to "hot" music?

Ouch!

[Lucius1958]

Very good idea!

In lieu of grinding down copper pipe, some hobby stores carry thin walled brass tubing of finely graded diameter, which might save some labor...

Bill

[JohnM]

I would imagine that a clear two-part epoxy would hold as well as solder since you are sleeving the repair with copper tubing. That way you can avoid further degradation of the pot metal since no heat is involved. I would rough-up the copper a little first so that it has some tooth for the epoxy to grip.

[Tinkerbell]

I don't know if any of you recall my pre-Ultona Brunswick tonearm with the two, interchangeable reproducers with pot metal "issues" that I posted pics for a few years back...

CIMG0859.JPG (156.97 KiB) Viewed 3354 times

I sent them off to Walt S. for repair, and he used a very similar technique of "sleeving" to put Humpty Dumpty back together again.

I'll try to post a picture of the repaired version later today when I dig my camera out.

[Mr Grumpy]

Thanks for the links, I wish I had that solder before I started all this!
That's typical me though, jump right into something and see if it works.
At least I know for next time.

I would imagine that a clear two-part epoxy would hold as well as solder since you are sleeving the repair with copper tubing. That way you can avoid further degradation of the pot metal since no heat is involved. I would rough-up the copper a little first so that it has some tooth for the epoxy to grip.

After I finished the repair I thought the exact same thing John, but at the time I was so frustrated with
the JB weld epoxy failing that I didn't want to put anymore faith in it. The sleeve combined with the epoxy would easily have the strength to keep this repair in place, probably more so than the solder and it would have been easier too!

I'll try to post a picture of the repaired version later today when I dig my camera out.

Yes please! If it's not too much trouble. Would love to see how a pro does it!

[edisonphonoworks]

It made an improvement, and it works, it is much better than no tonearm at all, so there is no problem with this repair. Pot metal parts are hard to find replacements for, as most of the spares also suffer from some problem too.