Outer groove distortion - Sapphire Embossing

[Estrada]

Hi fellow trolls,

Just thought I'd throw this one out there to see if anyone has had a similar issue or if I'm coming up against a known issue. I've searched the forum but couldn't seem to find anything.

I've recently started embossing polycarbonate using the Piaptk Sapphire embossing stylus. My lathe is an old 1930s thing which I've converted to belt drive. It has an Audax mono cutting head.

I have been making some quite nice sounding records but I've been getting some peculiar results with some 12" discs I have been trying to emboss. They play back fine in one of my turntables which is fitted with a cartridge which requires a high downward force (2.5 - 3.5g, I have it set at 3) but when I play it back on my main turntable whose cartridge only has a downward force of 1.5g there seems to be a lot of distortion/noise in the outer grooves, it seems to come right about 1 - 1.5 inches in from the edge of the disc and is ok until the end of the side.

Just wondering if this is something that other embossers have come across before.

[tragwag]

i never had luck with 12s embossing, maybe it's something to do with a slightly uneven blank?

[piaptk]

Yeah, 12"s are rough. The inevitable warp of the larger discs causes all kinds of problems. Also the increased linear velocity of the outside edge combined with the friction of the plastic and the embossers seems to cause lower fidelity for me on the outer edges, which is the opposite of cutting with a faceted stylus into lacquer. Our embossing styli work WAY better for me than any other previous embossing incarnation, but I still don't like embossing anything over a 10" (for that, and other reasons... takes too long, costs too much). If I DO emboss 12"s, I usually try to crank in a good half inch to get away from the outer edge as much as possible.

[Estrada]

Thanks for the replies. I think part of my problem is I was using a U.V. tinted polycarbonate for this particular test (rookie error perhaps). Clear seems to work better but the quality is certainly not as good on the outside of the disc. I’m thinking of trying embossing at half speed, I’m sure this will have its own challenges but could be an interesting experiment

[tragwag]

Thanks for the replies. I think part of my problem is I was using a U.V. tinted polycarbonate for this particular test (rookie error perhaps). Clear seems to work better but the quality is certainly not as good on the outside of the disc. I’m thinking of trying embossing at half speed, I’m sure this will have its own challenges but could be an interesting experiment

definitely possible to get usable results! though in my experience the speed changing thing was never usable long term

[EposLab]

There must be an issue at the settings.
I do emboss 7s & 12s with very good results and fidelity at the outer side of the 12s is significant better.
Only bad thing is that sometimes there is alittle more background noise and thats due to combination of the uneven surface / material and high angular velocity.
...and i playback all my vinyls with a Grado Statement with tracking force @ 1.5g and antiskating @ 1g !

Half Speed is something i like to try too. As for now i emboss all my 45rpm at 33 and the inner fidelity and higher frequencies are really improved. So i believe that half speed of 33rpm will be a real improvement .

[Estrada]

Thanks EposLab. Part of the problem was the type of polycarbonate I was using, a tinted UV resistant type which didn't seem to work as nicely as clear polycarbonate. That said I was still noticing a bit more surface noise at the outer edge of a 12"

I spent some time last weekend experimenting with cutting at half speed. The results are great!!!! Even on the UV resistant polycarbonate which I was having trouble with. I'm getting a much better response at high frequencies and overall the sound quality seems greatly improved and more detailed to my ears. I would definitely recommend trying this out.

[EposLab]

I'm really triggered for half speed embossing but i need to customize the idler wheel from 78 to 16 rpm!
You really have to try also an triangle embossing stylus! (https://www.lathetrolls.com/viewtopic.php?f=15&t=8676)
There are really improvements with it!

[Estrada]

Hi Epos, I've seen your thread about the triangular shaped stylus. That looks very impressive indeed. I would be very happy to try it but I don't think I have the capability to make one, are you selling these? If so I'd be interested.

[EposLab]

Hi Epos, I've seen your thread about the triangular shaped stylus. That looks very impressive indeed. I would be very happy to try it but I don't think I have the capability to make one, are you selling these? If so I'd be interested.

Thanks for your interest! soon you'll hear about it!!