cutting two grooves on one disc

[andybee]

Hello cutters!
A customer is asking, to cut 2x grooves with approx. 1.10min length on
one side of a 7inch. As this questions is asked not so often, I forgot, how to do this...
It is done with fixed pitch (wich is possible with our machine).... but then... ?
Any tips would be helpful!
Thanks!
Andi/my45

[Aussie0zborn]

Im told by somebody who did it that it can only be done with fixed pitch.
He used VMS80 and fed a 1kHz tone to the preview so that there was no pitch variation. You won't have this problem.

The question is... is it the first cut groove that makes the lock out or is it the second or do both grooves make their own lock-out groove?

[dubcutter89]

The easiest is to do it on a mechanical lathe where TT and Feedscrew are locked by gears…
Otherwise use a coarse pitch Setting and some luck to drop the needle in the Right spot… hey, who cares About ruining some master blanks


If both tracks are axactly the same length add some seconds to one track, this will ensure it will go further torwards the center. Then make a locked groove on that track.
Otherwise use the longer track for locked groove thing...


Maybe that makes sense.

Good luck!


LG
Lukas

[Scott_HUll]

HI,
I've done this and I can repeat it on a 12". Recently one double grove side for a commercial release.
It's a BIG challenge on a 7" but it can be done - I Figure three grooves are also possible.
Takes hours - and it's expensive !!! but when it's done - it's a hoot.
Yes, fixed-pitch is required. But I just disabled my Automatic Pitch control. The two programs have to be the same length .. Or one can be shorter - but each groove has to end at the terminal.
I watched the grooves as they were being cut with the scope and made small adjustments to position the " second" cut " between the groves of the first cut.


Scott Hull
Masterdisk

[Bill P]

I’m kinda late to the party with my post...
Here’s an acoustic recording (1911) on Victor Records that has 4 interwoven grooves. Each groove is about a minute long and was probably cut at a pitch of 25 lines per inch.

Here’s a link with full details:

https://adp.library.ucsb.edu/index.php/objects/detail/80198/Victor_35229