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Columbia AZ trunnion material?

Posted: Sat Aug 21, 2021 12:47 pm
by kirtley2012
I have a Columbia AZ graphophone I'm getting running, this being the first one I'd seen, I was going off things I'd read online that the AZ had no pot metal in it, I'm a bit confused by the trunnion, it's not brass, thats for certain, but I'm not sure what its made of, I thought it could be pot metal as it had placed a death grip on the lift lever, though it is possible that it could be aluminium and it was all just seized with grime and grease, does anyone know what it was made of?
The reason I ask is I am in all likelihood going to have to make another one, one of the screws is stripped out and I also found a hairline crack in the piece which could have happened in trying to separate all the parts and although I've got it together for now, I'm not happy with it

Re: Columbia AZ trunnion material?

Posted: Sat Aug 21, 2021 1:49 pm
by phonogfp
There are many AZ trunnions out there made of pot metal. Maybe all of them.

If you got it apart, cleaned, and reassembled to function, it sounds like all you need is a bit of cosmetics. With your skill, this should be no problem. I've seen wonders performed with JB Weld, careful sanding, and a little aluminum/silver paint to touch it up. I imagine the stripped screw hole might be repaired with JB Weld too.

Best of luck!

George P.

Re: Columbia AZ trunnion material?

Posted: Sat Aug 21, 2021 2:46 pm
by kirtley2012
phonogfp wrote: Sat Aug 21, 2021 1:49 pm There are many AZ trunnions out there made of pot metal. Maybe all of them.

If you got it apart, cleaned, and reassembled to function, it sounds like all you need is a bit of cosmetics. With your skill, this should be no problem. I've seen wonders performed with JB Weld, careful sanding, and a little aluminum/silver paint to touch it up. I imagine the stripped screw hole might be repaired with JB Weld too.

Best of luck!

George P.
Thanks George, I think pot metal is the most likely culprit

I have got it working, but the lift lever is a little loose now, I think I shaved a hair too much off in the lathe trying to get the lever off oops, and with the amount of work it would take to get it good, I might as well use the original as a template and make and plate a new brass part.

If I later post "Wow, JB Weld worked great!" then plan A might not have gone too well, but lets see

Re: Columbia AZ trunnion material?

Posted: Wed Aug 25, 2021 2:17 pm
by kirtley2012
That ought to last another hundred years or so

Obviously not plated yet, I’ll do that tonight

Re: Columbia AZ trunnion material?

Posted: Wed Aug 25, 2021 3:50 pm
by Curt A
That's perfect... the same repair that Jean Paul Agnard used to do. You should offer those for people who need replacements, since Jean Paul is no longer doing them. He would have people send him the trunnion parts, put them on the new piece and send them back fixed.

That's a permanent fix getting rid of the pot metal.