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I have been trying to repair a gear that is used to rotate an internal radio ariel in one of my sets. Unfortunately the part was originally cast in pot metal and has long since swollen, distorted and fallen apart. I have tried glueing it back together but because the metal has swollen it now won't fit. Also I have discovered that a small two teeth section is missing.

I had thought of making a replacement part - perhaps out of an easily cuttable mateiral to get the right shape and then using it as a template to make it out of something more permanent. How easy this would be to do - Im not sure but i'm open to any suggestions as to the best way forward.

I have attached some photos of the bits I have and where they need to fit.

I bought a reproduction a few years ago for my 9-55 it was made of plastic. I don't remember who made them but if you ask around somebody could tell you.

I have had some good luck repairing pot metal tonearms with JB weld.
One advantage you have is the parts are internal so it does not have
to look pretty. This allows you to use copious amounts of JB weld to
increase the bond strength. I would suggest cleaning the parts very
well, then use the regular slow cure JB weld. The quick set stuff is
ok for light repairs, but the slow set is better for parts that
will experience more torsional forces. The slow set stuff may run
and drip due to gravity so its a good idea to keep an eye on it
while drying.

I would like to recommend Devcon Plastic Steel 10240 rather than JB Weld. Nothing wrong with JB Weld, but DPS 10240 is stronger (and more expensive).
Also, wrap fiberglass drywall tape around the repair area a couple of turns. This will add reinforcement to the epoxy repair. Cut the drywall tape to the approximate size for the repair. It has a light adhesive on the back so will adhere to the metal and to itself.

Thanks for the comments. I have glued it together but found that the part was so swollen that it wouldn't fit. All the teeth of the part have expanded and swollen. The shape of the whole part has also become distorted so I don't think there is any other option but to remake the part really.

If anyone knows if anyone makes repros of this part please let me know although in the meantime I am going to have a go at fashioning a replacement myself.

SBH,

You could probably try fashioning one from cabinet grade plywood, AKA baltic birch, then copy it to aluminum sheet. The good news is that all you have to do is get the locations of the 2 holes, and gear teeth right. The rest can be solid.

I'd make enquiries at a few of your local T.A.F.E. colleges. Even when I went to TAFE back in the mid 80's, they could scan an item like this, adjust & complete it in the computer, and push a button and a laser would cut out a 3 dimensional copy of the original.
Sometimes they'll use stuff like this as a project for students to learn by, so it only ends up costing the price of materials (if anything at all.)

If you cannot find a repro, I would vote for making / having made a functional replacement, either out of plastic / plexiglass, or hardwood marine or cabinet-grade plywood ( many thin layers and few/no voids, unlike flooring / sheathing grades).

This piece is not a constant-duty high-wear precision part like a motor gear, so your swollen bits are still probably good enough to make a pattern.

If you have a floor-standing scroll-saw, ad some patience, you should be able to create a workable replacement.

Folks have made ( and still make ) funtional clocks entirely out of wood, so I think it's a possibility here...

Good luck !

Thanks for all the suggestions so far. I made a start last night and have made a copy of the original part in a sheet of plastic and cut it out. The light went at that point so i've left it to today to go further forward with it. Its only a template I am making so far as the plastic isn't strong enough by itself.

Once I have trimmed it to fit properly I will copy it in wood I think which should be strong and resiliant enough to do the job. I'll post some photos later of progress. So far its not been as difficult as I thought...