After cleaning the chassis of this newly acquired 1938 Rogers Radio. I noticed that the sheet metal can that holds the motor drive was slightly bent back. I removed the motor, and small gear reduction box. I noticed that one of the "larger" phenolic gears had about 15 of the teeth worn off.
It looks like it might be a "standard" clock gear. It measures exactly 1" across, 1/16" thick (I haven't measured the hole size yet, and it is on a shaft that has been peened over. (shaft only measures 1/4") so I'm assuming it might be slightly smaller). It has 96 teeth on it and the smaller brass gear it "meshes" with has 15 teeth on it.
There seems to be quite a few clock re-builders (and gear manufacturers) on the web. I guess my question is, Has anyone had a gear made, or come up with a replacement gear for a similar project that they can recommend might be worth dealing with ?
In the photo it is the larger (lighter in color gear).
Any thoughts are welcomed,... as this is new to me.
I found these guys,http://www.gearsmade.com/, I have never used them, but the site looks impressive!
I guess that's not to bad considering it would make the radio "whole" again. If it wasn't for our lousy dollar right now I might go for it.
But for now I will have to put it on the "back burner", until I get serious about re-finishing the radio. I will putter away at the chassis for the time being. It looks like I have a burnt antenna coil as well.
Previously a few people who needed a replacement for a stripped phenolic gear were able to find something in aluminum or brass at Stock Drive Products.
Their prices aren't cheap either, but you will probably be able to find what you want in the under $50 range. I don't understand how their search function works, possibly you would do better to call them. I'd expect there's a similar supplier in Canada, which would eliminate the exchange rate issues.
Thanks Dennis ! That is more like it. Prices are way better. Looks like something similar in brass, but with a hub is out of stock and about $20.00. Something in Stainless steel with a hub is a little more, but they have stock. I'd have to machine off the hub, but for that price you can't go wrong.
I would expect that your best bet would be to try to locate a replacement clock movement. Surely the same one was used in many makes and models.
You might try casting some new plastic teeth onto the old gear. The mold could be made off a good sector of the same gear.
There are a lot of casting resins out there.
Hi Ted. Thanks for the tip on casting some new teeth on the old gear. They are very fine teeth. One of the reasons I picked this Radio up was that it did have the motor drive. I have been collecting awhile now, these seem to be very scarce up here. I suspect it was a weak link in these radios (as well as being expensive) and as a result wasn't used in very many radios. Unlike the Zenith sets, these particular Rogers radios had "presets" on the back of the the radio so it would stop right on the station.
I do wonder if a watchmaker, or someone repairing clocks has been investigated? I noted recently when getting a battery from the guy I bought my watch from, that he had a form of CNC machine, and I have no doubt that it would cut gears, as mechanical clocks are full of them.
Years ago there was a gentleman in New Jersey who was a watchmaker and had the proper equipment to make small gears, I did get some from him but he has since passed on. The prices of the factory made gears at Stock Drive are lower than what anyone today would charge for doing one or a few at a time.
I'm inclined to think the smaller gear has 16 teeth rather than 15.
That produces a ratio of 96:16 = 6:1, which I would expect in a gear train in a clock run from 60Hz.
For two gears to inter-operate properly they must have the same diametral pitch and pressure angle.
You can estimate the diametral pitch pretty closely by measuring the gear.
It's very difficult to calculate the pressure angle; nigh on impossible with such a small gear.
Traditional products generally used 14 1/2 degrees. Modern ones use that or 20 degrees.
Dedicated products can use whatever they like.
It was common to use an odd-ball PA, forcing customers to buy replacement parts from the OEM.
In this application, close may be good enough.
If this is actually a clock gear, the loading will be very light, while if it is for some other function, it may not have to run very much.
One advantage of re-treading the original gear is that the hub or shaft can remain attached.
I have sen a couple of clock gears,where the was enough space, with a sector placed on the side if the sheered section. I have reservations on putting a tyre on a gear that small but I have done it to a cluster gear from a lathe.
That's about ten times what I figured it might be, wow!
You might contact Dennis Kaye who restores clocks. He rebuilt the clock for my Majestic radio.
I think this is for a motorized dial drive.