The Secret Society of Lathe Trolls

RCA's "Selectavision" did actually cut video signals in a disc, but since video bandwidth is several megahertz, the process encoded video as a capacitance type signal and the copies were pressed in PVC mixed with carbon that made the disc conductive. It was played back by a stylus that would suffer ...

This didn't cut a groove, but was a magnetic recording device that made freeze-frame and "instant playback" possible.

That model has the "school" or plain idler drive. The transcription model was direct drive. You can try it, but I don't think that model will have the torque required for an overhead and cutting.

Do you happen to have the model 12V-9? That was a professional turntable made by that company and was direct drive, pretty expensive and would also play 16" radio transcription discs. I think that was the only model they made that was direct drive. It was intended for professional use. All other Cal...

The school had these when I was in elementary school in the 60's. They were cheaply made and if I recall, the drive shaft on the motor looks like a needle and the idler is very small; about 1.25 or 1.5 inches. Bumps up and down against the different diameters on the drive for different speeds. Not m...

Just out of curiosity, do diamonds ground for cutting plastic have burnishing facets? They're sort of necessary for lacquer. I think diamonds resemble some of the tools used on metal lathes, more triangular without the burnishing facets. Anybody know about diamonds?

I've used acetone (nail polish remover) and pith wood and had no issues ever in decades. Just don't clean the stylus or advance ball over a lacquer on the turntable - if any acetone gets on the disc, it will dissolve the lacquer coating. I don't use plastic much at all, so I'm not sure about what ac...

And more information:

https://grammophon-platten.de/page.php?506

This has similarities with the machine in this video from 2009: https://www.iasa-online.de/plugins/video/2009/2009_IASA_Jahrestagung_Schallplattenaufnahme.mp4 The blank was a German 'Decelith', which I think was similar to a thick plastic embossing disc, but it's cut like a lacquer. I don't think De...

I might; let me check the docs I have for my Scully equipment when I get home from work today.

It has the "magic notes" logo and the name 'Columbia' under the diaphragm of the soundbox. There should be a decal on the lid (when open) that has 'Columbia Grafonola' and the logo as well. Cabinet could have been re-finished at some time, removing the decal. The tonearm design is definitely Columbi...

Sorbothane would probably be a good substitute for Prestoflex, which was a viscoloid-like material. You can get sheets and strips of sorbothane online. It's been a while since I've had my Presto cutting heads open, but if I recall correctly, the damper was about 1/8 to 3/16 inch thick, anchored at t...

My vote is for the original; sounded great, even on the acoustic phonograph. Second recording sounded 'thready and tinny' to my ears.

Yes, that's correct; I have two of the K series units and they are not capable of cutting spiral grooves. Only the larger overhead machines could do that. The smaller machines with an overhead (12 and E series) couldn't cut spirals either; just head up and down only.

If the unit originally had a crystal head, the drive is coming off the plates of the output tubes (~180 VRMS). This would fry a magnetic head. A magnetic head was made for the Recordio series, the Astatic M-41, which show up on ebay occasionally. However, to use this head with the original electroni...

Sorry this took so long; here are the two pages of the tech literature that came with the Grampian head:

This does a good job of demystifying the 78 manufacturing process:

https://www.youtube.com/watch?v=2zL53iEHf_0

I have the manual for this head; will scan it and post when I get home from work today.

If I remember right, the Recordette series had a built-in microphone; little plastic thing that stores in the lid of the unit and a cloth bound cord goes down through the turntable deck into the machine. This is also a crystal element mic, which what you're describing indicates that it needs to be r...

The link posted doesn't work. Is there another web address to use?