Pot Metal Troubles....

[WRDancey]

Hello!

New to the forum, and new to the hobby of phonographs and record collecting. I've always had a love for vintage music, and was recently able to purchase a 1920's era hand-wound Pal suitcase phonograph. The machine works well in nearly every way, except that the joint between the tone arm and sound tube is extremely stiff. Attached is a picture, with the joint circled in red.

I've tried to exercise the joint, but it remains extremely stiff. I fear that these pieces (which I assume are both pot metal) have swollen to the point that they are almost un-usable. I would like to know how others have dealt with similar problems, and am looking for suggestions to fix this issue without having to find a replacement tone arm. If there isn't any good fix, does anyone know where I might find a Pal tone arm?

Again, I am a novice so please assume I know nothing!

Thank you for the help and suggestions,

W.R.

[VanEpsFan1914]

Hello, and welcome to both the Talking Machine Forum and to the antique phonograph hobby!

The tonearm and reproducer you are showing are built by E. Toman Company. Toman arms are notorious for this problem but they are easy enough to fix if you can stop them before they have swollen too far. If you've been able to play yours it should be repairable. Besides, the nickel plating is in nice condition and that shows it's been treated pretty well.


First, remove both the reproducer and that "Millenberg Joys" record by McKinney's Cotton Pickers that you don't want to break. Then unscrew the three screws holding the base of the tonearm to the motorboard of your talking-machine.

Get some penetrating oil or sewing machine oil--you could even use 3-in-One or WD-40--to loosen up the bolt on top of the arm. Carefully unscrew it and work the tonearm apart. The crook should slide out of the main tonearm tube.

The parts should be separated. Grab a rag and some gasoline, kerosene, acetone, lighter fluid, naphthalene, denatured alcohol, whatever you have that is carcinogenic and flammable and cleans stuff. Now there will be some old oil and grease on this, and it will be gummy and nasty. Clean it carefully. Set all your
flammables aside, dispose of the rags safely, and wash your hands. They'll probably smell odd.

Next up, take a rag and some valve lapping compound like the old green Clover compound from back in the days of antique cars, and polish up the inside and the outside of that tonearm joint. You don't need to scrub the finish with it, but definitely all the parts that touch. Keep grinding and checking until they are the right diameter and fit together with that Goldilocks fit: j-u-s-t right!

And now you will want to take a little sewing machine oil, synthetic grease, model railroad grease, or whatever you have (probably not Vaseline, it goes gummy with time) and then lubricate the joint as you fit it back together. Put the screw back in and tighten it snug, but not too tight--you don't want to crack the pot metal.

While you have the reproducer off, it will be good for you to rebuild it with some new gaskets. Someone else will be better to guide you through that; I like fixing the older machines that are fairly straightforward to buy parts for. You will need some thin rubber sheet to build a new tonearm gasket (that red piece that holds the reproducer on) and then some delicate surgical tubing or old carburetor gasket material or something to make two diaphragm gaskets. Having these rubber parts replaced really does boost the sound, and it makes records last and last!

Once you're all done, change the needle (old music is too awesome for crummy needles; I'd suggest buying the best you can find) and then call your friends, roll back the rug, and see who still knows how to fox-trot!

Have fun, and welcome to the forum! You seem to have at least one really cool old record--stick around! We've got lots and they do come up for sale.

Happy repairing!

Charles

[JerryVan]

I agree 99.9% with Charles' advice. I personally would not use the valve lapping compound to free up the joint. My fear would be that the grit of the lapping compound might effectively "lock-up" the joint as soon as you fit it back together. If you go this route, gently ease the joint back together, while at the time, working the joint back & forth to "grind in" a clearance between the two pieces.

Another alternative, would be to carefully file the diameter of the crook, (the part that holds the reproducer and swings up & down), where it fits within the arm. Going slow, with frequent try-outs, will be the way to go.

[VanEpsFan1914]

Oops! Thanks Jerry--I forgot to mention: if you use valve lapping compound, clean it off before you reassemble the machine for its trial runs. You don't want it to stay in there and, when mixed with oil, turn into a sandpaper slurry which will eat up the inside of the tonearm.

[WRDancey]

Thanks for the great advice guys!

I cleaned up both pieces as suggested, removing a fair amount of old oil. Afterwards, I weighed the pros and cons of using either valve lapping compound or a finishing file. In the end, it seemed to me that a file offered a bit more precision than the lapping compound, so decided to gently file down the crooks diameter. This worked like a charm! When done, I added a bit of sewing machine oil and reassembled everything. The machine sounds much better now!

Now, my next question is this: What environments are pot metal happiest in? Also, is there any way to preserve pot metal and mitigate the swelling?

Thanks again,

W.R.

[VanEpsFan1914]

Hi, W.R.!

Glad to hear you got the repair done so quickly! A file is a nice tool as well for the job, and sewing machine oil should last a long time without getting too gummy.

To preserve your machine for the long term, it helps to understand more about the metal itself.

(Disclaimer: I'm not a metallurgist, so some of this is probably wrong. I picked up most of it from phonograph collectors and wikipedia and all that--so it's nothing but young collector hearsay. Sorry bout that...But at least it's what I heard.)


Pot metal is good for talking machine parts because it melts at low temperature, can be cast with fine detail and easily worked, and is a cheap alloy of zinc and sometimes lead. Zinc oxidizes very easily, as anyone who has worked on galvanized metal knows, and your pot-metal tonearm would have been plated with nickel (or maybe chromium?) and sealed up that way.

Now why it swells--is due to "macular degeneration," or an expansion in the crystalline structure of the metal. Brass doesn't have that problem, and that is why the tone arm on a real Victor Victrola (which used all-brass parts for most of the run of those models) will show up dented while a Columbia or a PAL machine can have a shattered arm. But pot metal has a very rigid crystalline structure in the metal itself. It isn't malleable and cannot be worked or annealed without shattering.

Why it swells--lead and zinc react to each other, and can push each other apart. The dies from which the tonearms and other parts were cast had to be treated with powdered graphite or lead dust in between molding sessions, much like people will spray PAM on a skillet or waffle iron to get the batter out after it cooks. Graphite, to my knowledge (which is pretty limited) doesn't react. Lead does, and on the molecular level. So if they treated it with lead dust instead of graphite (carbon basically) then it will be more prone to decomposition.

Some alloys such as Zamac (pot metal of a certain type) have lead in them, and sweepings from the foundry floor. This is why many antique toy trains are missing wheels because of "zinc pest" causing them to warp and shatter. If you think phonographs are bad about pot metal, just be glad you don't collect antique model trains!

Anyway, to preserve it: keep it dry and fairly cool. There is no way to prevent it from happening but most of these E. Toman branded tonearms can be kept for a very long time if they are away from humidity. I have a late 1920s Edison Amberola 30 phonograph (cylinder player) that carried a pot-metal Diamond C Reproducer. The machine had been thrown into a damp place in Florida until the bottom rotted and the insides were colonized by cockroaches. I was only able to get it playing by removing the reproducer and sanding the joints with sandpaper many times--it took twenty minutes of work before the machine finally went sputtering back to life. No, I didn't junk it...it's currently fully restored and plays with astounding fidelity. Ever since its rebuild I have kept it in a dry place with lots of oil, and, believe it or not, it's my only phonograph that has never broken down on me when I was playing it.

Really, your machine is going to fall apart before that tonearm does. So I'd say, keep on enjoying it and pass it down to your great-grandkids!

Also, thanks for the follow-up. Lots of new collectors post once or twice and never come back to the Forum. We're glad they enjoy their collection but we'd all love to hear about their adventures in phonograph world.

[JerryVan]

Bottom line, it took 90 years to get to the point that it has. It's not going to get bad again anytime real soon. If the decay were that fast moving, (as some examples have been), it would have crumbled to nothing long ago.