Dumont (Stromberg) RA-103 phenolic tuner gear

[@blobscott]

Bob, take the parts one (i.e. the one with the broken dial) and drill out the swage (pressed over metal) on the back - i.e. the metal that is currently holding the good gear on. Take the good gear and open up the hole until the ID fits just over the swaged metal diameter. Then, a few drops of super glue and just glue the good gear onto the face of the bad gear, making sure to align the teeth. I suspect there's plenty of clearance for a double thick gear and this method allows you to leave the tuning dial fully intact on the part you're repairing.

[@billharris6886]

Bob, I know of no simple remedy. They are using a bushing with a thin-walled area so the bushing can be flared into a spacer on the opposite side of the dial. To remove this, would need to carefully drill out the rolled flair. You would then need to machine a new part on a lathe. An Arbor press is needed to reassemble the newly machined parts back on the dials using a custom made flaring tool. However, probably the hardest part is during the flaring process. To get a nice tight connection between the dial and collar or bushing, considerable flaring force needs to be applied. Since that force bares upon the metal and plastic dial, it would be very easy to shatter the dial. Given it's age, combined with years of heat from the tubes, has likely made the plastic dial very brittle. The gears are another problem altogether. I'm not sure how you would address that for a reliable and practical fix. With all these custom plastic parts that are becoming increasingly difficult to source, the knowledge of making parts via a 3D printer would come in very handy.

[@mikefinn2101]

Bob you always perform miracles so I am sure you of all people will do what is right. Nice to see the details very interesting many thanks Mike

[@adriannovotny4373]

What about doubling up both gears since the pinion gear is much wider than the phenolic gear? It seems like the forward/rear position of the rotating dial has enough wiggle room to accommodate the width of a second gear, but it's hard to tell through video. You could drill the tube rivet off the good gear, open up the gear inside diameter to clear the rivet crimp on the bad gear, and then glue them together with the teeth lined up. Alternatively, if you can post a clear head on image of the gear with an accurate measurement of the outside diameter, it would be pretty easy to CAD a reinforcing ring with the right teeth to glue to the side of the bad gear. I see other commenters mentioning CNC machining and 3d printing, but I think laser cutting a ~.04" steel or brass sheet would be cheaper/easier here - there are a ton of online services for that. Plus you wouldn't need another spare gear if you ever encounter another bad tuner.

[@jimhall9360]

Could you remove the gear from the broken disk, enlarge its ID, and laminate it with your partially stripped gear?

[@69Dartman]

3d printer might be a good option to make a new gear or parts. I'll probably get one someday soon, seems handy for all kinds of things.

[@bandersentv]

That's not really the problem though. I have a good gear from the parts tuner. It's attaching it to the bushing that's difficult.

[@69Dartman]

Your original idea of some sort of heavy duty thick epoxy is probably a good one then. I had a beater 82 Celica that needed a new temp sensor and when I tried to remove it I messed up the threads and I couldn't make a thread sert work. I hogged it out and filled the hole with liquid steal and a thread sert that was the right size. When it sat for a week I gently screwed in a new sensor. I had to solder a ground wire to it and it worked and never leaked for a long time before I decided I was tired of fixing all the issues and sold it cheap. It did have over 300k on the body.

[@notimetolooz9655]

I would not try to drill out that bushing, it is thin with a large diameter. The drill bit would catch. Very likely the fragile parts would be damaged. A Dremel tool and a coarse stone or fine file bit would be better for brass. Reduced speed would be best. Just grind the edge of the metal bushing away a little at a time. Your choice of glue, I would go with epoxy. Make sure there is no oil or grease on the joint before gluing.

[@hotpuppy1]

Getting that disc off will take some doing and putting it on something else will be harder. Re-engineering and machine work to make parts.

[@entity9742]

And its been plinkotwinkulated.... Real shame about that buuut if you can reglue it and add a slight mask to the glue spots (or add a plexi glass backing) then it could be a seamless repair Im currently working on the 8-301w sets and the safety sheilds are the same way (polishing them is a nightmare with how fragile they are)

[@SeekingTheLoveThatGodMeans7648]

Maybe you could get one CNC machined, perhaps from hard Plexiglas if not metal. This looks like it needs to be firmer than anything that can be 3D printed.

[@bandersentv]

The gear? I have this one that's fine. The question is how do you mount it to the metal bushing without damaging anything?

[@SeekingTheLoveThatGodMeans7648]

@@bandersentv This looks like a crimp job, and maybe epoxy could help hold it even firmer. A new bushing maybe? I've seen Dave on Dave's Radio Adventures do crimping, if I don't misremember.