Columbia 612 floor gramophone, a real beauty !

[nostalgia]

Thank you Carlos, this is very interesting information, and the natural next question is if possibly all the Plano Reflex arms for the model 156a were made of pot metal or not, and even possibly all have this problem after all these years. Do you say you have model 156a with a PlanoReflex arm that is stable and not distorted?

[CarlosV]

Thank you Carlos, this is very interesting information, and the natural next question is if possibly all the Plano Reflex arms for the model 156a were made of pot metal or not, and even possibly all have this problem after all these years. Do you say you have model 156a with a PlanoReflex arm that is stable and not distorted?

The one I have is model 133a, floor model with a large bifurcated horn (I believe it is the largest horn that English Columbia produced). The plano reflex tone arm is long, not sure if same length as the 156a, and it has no mechanical problems. It is a great machine, soundbox is excellent and has a great sound reproduction.

[anchorman]

This is an interesting topic for sure, if the Plano Reflex arms are made of pot metal or not. I talked to another collector some days ago, who have been collecting for 50 more years, and he says they are not made of pot metal. Myself I have no idea, is there a way to see if it is of pot metal or not?

I know that the portable plano reflex arms are pot metal - because two of them broke down in my machines and then their composition became evident (I replaced both with spare arms). I have also a large cabinet with a similar tone arm to the photo, but it is stable without distortions. I am not aware of a method to identify the pot metal unless it is visually detectable, either by cracks or shape distortions. When the pot metal is well manufactured, as is the case of these Columbia arms (and similarly the HMV 5a/b soundboxes), it is not easy to discern, but the shape distortion in yours may be an indication of pot metal, as brass would not distort without external pressure.

Pot metal is easy to detect. Scrape through the plating in an innocuous spot where it won’t be seen. If it’s brass it will be yellow, if pot metal, it will be grey. I’ve been thinking about this for a while, and I think that lead less pewter may be a possible substitute for re-manufacturing parts, but it would have to be a labor of love, and may be entirely too soft. Almost as easy to have an arm made up of brass than to use pewter. Any competent jeweler/silver smith ought to be able to do this, but it’s going to cost $$$$ most likely.

The arm in question looks like it was bent to me, more than as if it were some kind of metal fatigue. I would speak to an instrument repair person before talking to a blacksmith/iron smith. Not sure if something is lost in translation there, but those people tend to work with a lot less delicacy than a jeweler/silversmith would do.

[anchorman]

I know on my portables, that the end piece that the reproducer attaches to are brass. I haven’t probed much into the main section of the arm, but the two that I have currently in my possession seem to be pot metal, but high quality.

Pot metal is wonderful stuff, unless it is contaminated during melting and casting. Especially iron contamination has been shown to be extremely detrimental to alloys of zinc and other white metals traditionally used for (relatively) low temperature alloys for cast parts. When made properly, these alloys are very durable and have many good physical properties. I may be wrong, but I tend to assume that if pot metal from 100 years ago is looking good, it’s probably going to be fine another 100 years unless severely abused. The worst of it died shortly after it was made. It seems the bad stuff has a relatively high initial failure rate, and the longer it lasts, the less likely it is to crumble and fall apart, since the disintegration is a factor of time, temperature, humidity, and stress placed on the part. Whatever they used for the internal section of the horn on my 112a looks like it was cast yesterday. I don’t fear that it will go bad any time in the future, unless severely physically abused.

[nostalgia]

The strange thing about this arm, is that another forum member, with the exact same machine, had the exact same problem with the tonearm. Unfortunetaly, due to the forum problem showing photos from old posts, the photos are lost for now, but here is the thread: viewtopic.php?f=11&t=46490&hilit=model+156a
We compared the two tone arms, and they looked exactly the same, bent. If we hadn't known better, we would have believed they were made that way. Actually, I thought it was supposed to look that way back then, because it was the first Plano Reflex arm that came into my possession, and it was only when re mounting the machine after a complete restoration, I was very upset when discovering the tone arm was scraping the surface of the record, and forum member Soundgen first pointed out to me, as an experienced gramophone enthusiast, and told me the tone arm was distorted.

I do not have access to metal work tools, and do not want to spend big money on fixing it, since the charges by jewelers etc is extremely high in a high cost country as Norway.

If I only knew what had happened to it, it would be one step closer to knowing how to attack the problem. There are no cracks in the tone arm, and when looking at its grey interior, I believe it must be made of pot metal, thanks for telling that, "anchorman" When looking at it this evening, I am more tempted to put it in a simple vice, and try to bend it back into shape, or even use a hacksaw and cut it in two, and then cut off a small part at the first bend, and then solder it back together.

[Inigo]

As a semi-profane in Columbia machines, my first thought when seeing that problem was the typical lid fall onto the tonearm when playing. Of course this is typical of portables, not of console machines whose lid can be closed whilst playing a record. But... !

[anchorman]

The interior will be plated also, just not polished like outside. So you will have to physically scrape through the plating to see for sure. Easiest way to do that is to take a fine file and run it across the end of the fitting if it is somewhere where it won’t be seen. I would avoid putting it in an ordinary vise. You need to make special jaws to grab the round (and tapered) exterior of the arm to prevent damage. Hard wood like maple can work for this, but the fit has to be very good. You may also need to make mandrel a that fit inside the arm. Steel that is polished is ideal so it doesn’t mar the surface and is strong enough to use to move the metal where needed. If you’ve never done anything like this before, it’s not recommended to start on something complicated.

Best to make a plan of attack, think about it for a week or two, then think about it some more. So many ways that a person could approach such a problem, and only one or maybe nine of them are the best or right way.

[anchorman]

As a semi-profane in Columbia machines, my first thought when seeing that problem was the typical lid fall onto the tonearm when playing. Of course this is typical of portables, not of console machines whose lid can be closed whilst playing a record. But... !

Two machines with the exact same type of damage, this scenario is much more likely than the pot metal warping the exact same way twice, unless it’s a casting defect that exists outside of the realm of typical pot metal deterioration.

[anchorman]

You must also be aware of the possibility that the threaded section is brass but the elbow itself is pot metal and the two are soldered together somehow. I have seen this before on certain parts.

[nostalgia]

Myself, I still doubt the cause is that the lid has fallen down on the tone arm, since the gramophone is so deep inside (10 cm deep), and there are no signs of the screws holding the base have been stressed and if the lid falls down it will not even hit the end piece of the tonearm including the sound box in upright position. I actually now tested this, applying the shorter Plano Reflex arm, and the lid does not hit the soundbox in upright position if the lid is falling down. If however such an even still has caused the tone arm to bend, maybe I should try give it an instant shock from the other side...
But, I can of course be wrong thinking a fallen lid has not caused the problem, I am wrong all the time, as of today...when I spent 7 hours trying to repair a Heinemann motor in a US made Pathé machine, and did the wrong things all the time..
I have been thinking about this tone arm for two years or so now, but will spend some more time thinking, before deciding what to do.
Thanks anchorman/Inigo/CarlosV for all inputs, I will try to reason out what parts are pot metal or not, and yes...I have seen the threaded sections are obviously made of brass, they are of a more yellow coloring.