Repair Pot Metal Reproducer

[columbia1spring]

Members,
I came across a phonograph where the reproducer was cracked from being pot metal. I passed on buying it.
It was fully intact , not missing any pieces and still played.
Can this be repaired/ saved? And still look nice?

[Curt A]

Short answer: NO

[Lah Ca]

Short answer: NO

NO--This is probably the best, safest, least costly and most practical and pragmatic answer to the question.

However, I have an acquaintance with a metalwork shop. He claims to be able to weld pot metal. Not an easy or entirely safe task, and one fraught with potential for total disaster. But he does repair on heavier things such as car parts.

Curious, I started doing online research. There are lots of sites saying that pot metal repair is easy--generally these sites are also selling something. The more honest sites say that it is not easy and is something best left to experienced professionals.

A rough and jumbled summary of what I may have possibly learned vicariously about pot metal repair:

There are easy repairs such as epoxy or Marinetex, useful only for decorative objects that are not handled. These repairs can be painted but not plated. They are not durable.

A more difficult repair is soldering. It is also dangerous (zinc is toxic) if you do not know what you are doing and are not properly equipped. And you can easily destroy what you are working on. And it seems solder repairs make plating very difficult or impossible. Solder repairs may not be very durable.

An even more difficult repair is copper flash plating followed by soldering. Better apparently than just soldering but .... also dangerous and of questionable durability.

And then there is welding. Quite challenging. Requires skill and experience and a delicate touch and very fine control of equipment. And it is dangerous and unpredictable.

And if you want the repaired object to be plated, there is a lot of prep work to be done before the repair.

Conclusion:

I suppose that if you had no other option and it were really important to have something repaired, sending the object to a professional for a feasibility appraisal and a quote might be a way forward. Or if you are already a skilled and experienced welder with proper gear and safety equipment, you might try expanding your welding silks to include pot metal.

Otherwise--NO--This is probably the best, safest, least costly and most practical and pragmatic answer to the question.

[OrthoFan]

You say it played, so obviously it was all in one piece. I take it you're talking about hairline cracks?

I have an Orthophonic pot metal sound box that had a few surface hairline cracks. I was planning to get a replacement, but to "hold me over," I applied some Krazy Glue to all of the cracks. That was 26 years ago. I just looked at it, and all of the cracks are still plugged, with no evidence of spreading.

I've also used Krazy Glue to repair a pot metal tonearm support base for a 1940s Birch portable. In that case, the support ring was cracked in half, but it was a neat break. That also held up just fine for the ten years I owned the portable. (I sold that about 20 years ago, so I don't know what condition it's in now.)

Of course, the best bet is to get something without any cracks.

OrthoFan

[Curt A]

When I said "NO", there are situations where a repair might be possible. My experience with heating a pot metal part turned it into a pool of liquid gunk. Another part that was essential for the operation of a record repeater crumbled into a thousand tiny pieces. Fortunately I took a picture of it and re-made it out of nylon, which works better than the original.

So, while it might be possible to fix something made of pot metal, in my opinion it would be better to machine a new one out of brass - especially if you want to plate it. I hate the stuff so much that I wouldn't buy anything with pot metal parts... Save yourself a lot of frustration.

[MarkELynch]

The big problem is that a pot-metal part made prior to 1930 is that it never stop expanding. I have 1927 Victor changer parts that looked okay 30 years ago that are now hopelessly cracked and swollen out of spec. The post attached to the potmetal casting pictured here was vertical at one time. The only real solution is replacement. Advances in metallurgy in 1930 make some parts stable or repairable. For example, the potmetal Orthophonic soundboxes labeled RCA are almost always good.

Mark