The Secret Society of Lathe Trolls

jornibudich · Joined: 06 Jun 2007 Posts: 7

Hello there guys - Just got a box full of dead stock 10" yellow Audiodisc and there were spots on the surface... I cleaned them and tried to cut...BUT, I killed 4 steel needles and the noise while cutting is just awful... THEN, I tried to adjust the weight of my cutter-head (I am using a vintage REK-O-KUT Imperial II) and after hours of suffering, kinda balanced the angle but still, certain areas were cut but some other got sticky and the sound still terrible.
I didn't have any problems when I used new acetates and I am afraid to use my zaphire with those blanks - TO MY QUESTIONS:
-Are those OLD acetates "useless" and the ones creating the problem? or...
-Did I create extra trouble by moving the screws in my lathe to change the cutting head weight?
PLEASE, I will HIGHLY appreciate any info or any literature about right weight and angle for cutter , will be GREAT!
Cheers
Jorge (Vancouver)
_________________
JORNI (Vancouver BC)

cuttercollector · Joined: 11 Jun 2006 Posts: 265 Location: San Jose, CA

Did you kill the steel cutting styli by cutting through to the base?
I had to fiddle with how far I inserted the stylus into the head, which changes the cutting angle, plus the weight to get a quiet silent groove. Then that was only for some lacquers - others were still quite noisy. If you can't get results
(I'm presuming an unheated stylus here) by some combination of gently warming the discs and fiddling with a slightly less steep cutting angle, then sneaking up on the depth adjustment so as to not break through to the base, then I would say to forget those blanks. I had a friend go through the same with a Scully/Westrex. He trashed an expensive heated stylus.
One more thing, they shouldn't ever be "sticky" unless they have been in an environment that is causing the surface to break down. You probably know from your other lacquers what a proper chip looks and feels like from the cutter.

emorritt · Joined: 09 Nov 2006 Posts: 61 Location: Louisiana

Were the spots mold (usually greenish colored) or palmitic acid (powdery white/yellow) leaching out of them? The 'yellow' Audiodiscs haven't been made in forever, so I doubt they're usable for cutting - too dried out and probably losing palmitic at this point. You might try adjusting the cutting angle as suggested, but if the coating on the disc is dried out as I suspect, you'll get a noisy groove. I have some Allied blanks I bought when I was in high school in the 1970's and they no longer cut quiet - even with a sapphire, although they're probably years away from beginning palmitic acid loss.

Steve E. · Posted: Mon Jul 23, 2007 7:29 am Post subject:

Yeah, I've tried cutting with old acetates. The problem is that they get really HARD over the decades. So they are probably useless. You are much better off using new stuff from Apollo or Transco.

cuttercollector · Joined: 11 Jun 2006 Posts: 265 Location: San Jose, CA

One old guy told me of a (literal) rule of thumb test of trying to indent an area where you won't be cutting with your thumbnail. If it wont take a mark from that, it's probably too hard to use. Someone else told me or I read here that old hard lacquers could sometimes be softened with mild heat and made useable again.
One more trivia question. I should know this but it keeps coming up on this forum. AFAIK, Apollo and Transco sell new lacquer blanks, lacquer thinly coated over an aluminum base. There are variations of course but that is the basic idea. Even all the old records for home units were lacquer coated something - steel, aluminum. cardboard. So, where did the terme acetate come from and is it a diferent thing? I had always heard it was. I had heard that it was a thin acetate plastic disc that was tried for mostly radio station cutting for direct playback of commercials delayed broadcasts etc., not mastering for plaiting and pressing, because of a shortage of the lacquer coated blanks during or shortly after WWII. Can anyone else verify or correct this story. "Cutting wax" and it's variations I can understand as that was big in the 20s - 30s to use thick wax cakes for commercial 78 mastering before the lacquers became popular for that purpose. In fact I guess lacquer technology was around then by Presto and others for direct playback so called "instant recordings" but the technology was not considered good enough for commercial mastering for plaiting and pressing, as shown by the wax being used in that RCA "Command Performance" film from the 30s.

cuttercollector · Joined: 11 Jun 2006 Posts: 265 Location: San Jose, CA

Also, just found this doing a google search of acetate vs. lacquer records.
Pretty interesting as it talks about the chemical composition and stability of most recording materials and formats.

http://www.iasa-web.org/taskforce/taskforce_04.htm