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Well, I received my "Mystery Control" from the gent on e-bay, just as described. Beautiful shape inside- I don't think it was ever opened! The warranty sticker was still on the bottom. Great condition inside, and the original battery still in place. Even the rubber covered wiring is not in the least deteriorated!
However, the bakelite disk for the dial on top has warped. Is it possible to heat and flatten the disk, or should I just file the dragging sections a little, or shim it out?
Scott
Old Cars, Old Radios, Old Pipes and Young Women... What more is there?
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I doubt it's bakelite--probably is more like Tenite Celluloid. Does the plastic give off a sour-milky odor? If so, that's definitely Tenite. And while you can reshape it by applying heat, I think it would be pretty easy to do more damage to it.
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The dial is a celluloid acetate plastic called Tenite, introduced to the industry in 1929. I warps very easily with temperature and age. It cannot be easily flattened. If the warp does not interfere with the rotation, I'd leave it alone. I've heard others that get a small flattening by pressing under some weight in a warm environment. I suspect this would take a long time with minimal success.
Tenite has a temperature of deformation much lower than other newer plastics, so storing any Tenite plastic in a hot attic say, over time, will warp it. The cellulose plastic also has an affinity for moisture absorption, again causing warping, like a damp basement or garage or barn. Aging effects in the chemical makeup of the Tenite also contribute. At the time Tenite was a cheaply produced platic that could be easily moulded and given "swirly" effects. It was not meant to be perfect 50-60 years later.
See the Mystery Control section of my site for more info.
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The warpage does interfere with the rotation- I will attempt the "weight in warm location" fix, and see if it helps any. Then I might try shimming under the disk- about 1/8" should do it...
Thanks!
Scott
Old Cars, Old Radios, Old Pipes and Young Women... What more is there?
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I would try shimming.
Every Mystery Control unit I've ever seen has this affliction to a greater or less degree, for the very reasons Chuck outlined.
--
Ron Ramirez
Ferdinand IN
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Makes me wonder if Larry could make new straightened castings of these as well?
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I'm sure he could, but the demand is very small, like most unique castings in the antique radio hobby. The initial setup costs wouldn't be recouped by selling only a few. Economy of scale bites you with this kind of repro. Not sure where a break-even point would be, but I'd guess you'd have to sell many dozens before profit shows and payback on initial costs is covered.
Also the center "screw cover dome" and finger-stop would need to be reproduced as well to achieve proper color match . . .
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Just an FYI Upate for the Chem Majors out there. 
Found my info packet on Tenite, also commonly known as Tenite Acetate, a Cellulose Acetate compound.
Max Temp for Short Durations = 180°F, 120°F long term (but not years stored in an attic or basement!) 
Heat of Deflection (start of deformation) = 52-105°C (125.6 - 221°F)
My attic at home hits 120°+ easily in the typical Chicago Summer!
Tenite starts to flow/creep at 55-95°C (131-203°F)
Even long-term heat from the tubes in a radio will do a number on
a Tenite grille or pushbuttons or knobs. Witness the Tenite Philco
pushbuttons and dial escutcheons that disintegrate on the 41 and 42
model high tube count consoles.
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Right you are, Chuck. I bought my 42-400 Philco from friends who were the original owners. I bought it in 1948, and the original push buttons were already shriveling up. I went to Philco Distributors in Detroit and got a new set. They had only the wine colored types, so I bought them and they looked good. Can't recall when, but these dried up also, so I found another set of PBs, this time in the original color. They are now getting grungy, so here we go, again....I have another new set of them to install.
Tenite I was a plastic by Tennessee Eastman, in Kingsport, Tennessee. Back in the late thirties, we'd read about the beautiful things that could be made from plastics, the miracle stuff. It was all Tenite I, of course. The car manufacturers went ballistic on using the stuff, and it looked beautiful for a while. Steering wheels were done in it, and cracked into several segments by the end of WWII. After about 1943, there wasn't a '39 Buick with a good steering wheel The center dash grille on the '38 Cadillacs was Tenite I, along with the steering wheel and control knobs. Those items are searched for by anyone restoring those cars today. I have two '38 Cdaillacs, and the plastic work on one is still original (I'm the second owner), and I can't explain why.
There are services that will re-moild steering wheels for about $400 each, and I've seen beautiful results. I have four 1941 Cadillac wheels that I'm going to have done. As good as the interior might be, a crumby steering wheel spoils it all.
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