Presto K8 Newb

[jamesmc]

Hi Everyone,
Complete Newbie here. I recently acquired a Presto K8.

I am embossing with a Sapphire needle onto Makrolon Polycarbonate.
Presto 5c cutter head, it's condition or angle I really don't know much about, I know the head has not been refurbished but the rest of the lathe has.

My first attempt at embossing was a song that was modern and quite dynamic (soft acoustic guitar/vocal to start and then louder chorus sections). It was a bit liberal in the Sub frequency extension and out of 4 attempts I got one disc that was almost decent. It was easy to ride the gain too high and have distortion. Fair amount of surface noise too during quiet intro.

Tonight I was contemplating all kinds of adjustments but before I did any of that I sent Booker T and the MG's "Green Onions" to the Presto. This time I had an XLR adapter made so I could go thru the mic input rather than radio input.

The result was actually much better!! I may have adjust the cutter head weight slightly too, but how much, I don't know. So I tried to revisit the first song again and hold back on levels a touch...still not as pleasant of results as the Booker T song.

I really do wish to get the best out of this unit with time and learning. I understand it is mono and maybe not considered the most hifi unit.

Couple early questions:
1-How important is the heating up of the Polycarbonate? All I had at the time was a 60 watt LED.
2-Should I be looking at angling this cutter head potentially? It is working the way it is, could use a little less surface noise.
3-What is going to be my best audio situation (Sapphire + embossing on Polycarb, PVC, Acetate, cutting with Diamond etc...)
4- with more modern recordings should I be cutting out the frequency bands that the Presto can't really produce before sending the audio to it (low cut at say 80hz and high cut above say 10khz). Do these frequency ranges only serve to overdrive it/mess it up?
5-any and all tips greatly appreciated. I dream of consistency on this presto K8 in the future ha ha

I've attached a couple video's showing my embossing the Booker T song/playback and a picture of my set up with this lamp.

[symatic]

sounds like you're getting way better results than my attempts using a 5C

however I'm using a pretty bad motor, and my bearings were basically non-existant. I'm waiting on the bearing being repaired before I can try again.

your stylus looks a different shape to the sapphire's I've got, mine look more conical and yours appears to have a flat front an a heel on the back (looking at your "embossing angle" video.

for your first 2 questions, so far the advice I've had is to experiment a bit with heat and angle. keep cutting Green Onions with different settings and compare them.
question 3 - theres a fair amount of discussion on the forum about that. Different plastics require or at least benefit from certain Stylii of different shapes/materials.
question 4 - I think it made an improvement for me when I EQ'd some of the frequencies that the Head probably wasn't even doing. Again try some A/B comparisons with and without the EQ and see what sounds best.

Good luck and please keep posting video/audio, it's great to see how other people do things.

[jamesmc]

Thanks symatic. I got excited when working with Green Onions but immediately was brought back to reality when I went back to embossing something I had recorded myself (still yet unmastered) as it just didn't cut thru the surface noise as well and distorted quite easily. Example attached. Love to hear anyones theory on why that may be?

[SONARC]

Hi there jamesmc -

Honestly, based on what I'm hearing in your video clips, the playback doesn't sound half bad at all. In my personal opinion (somewhat based on what I've learned at a few Lathe Camps, combined with my own trial and error experiments), I *do* think you can benefit from a tad more heat - you can pick up a pretty basic heat lamp / fixture at a hardware store for less than $20 (I've been using a 125W bulb in a 150W fixture, clamped to a mic boom stand over my platter), and I honestly think you'll hear a bit of a difference with the heat, and also some minor angle adjustments of your cutting head.

Have you tried the same tests with the head leaning back a bit? Like the example was given to me, as if you're walking and dragging a stick behind you so it leaves a trail; approx. 4-6 degrees, or thereabouts. If you haven't already, try experimenting a little with some of these ideas, and see what kind of results you get compared to what you have so far. Also, it looks like you're testing on a 12" disc; maybe try a smaller diameter, like 7 or 8", until you get consistent results you're happy with. I'm just thinking that you might be getting a tad more outer groove distortion with the larger surface. I think everyone's tweaks are going to vary slightly, so there does seems to be a bit of room for experimenting and finding the settings that work best for you. Good luck!

[jamesmc]

SONARC,
Thanks for the reply. I was impressed with the green onions result if only for the fact that I just got this K-8 and I don’t have any idea what I’m doing ha ha but it’d be good to get to to consistent results...if that’s even a thing. I had walked away from experimenting with the machine for a few weeks but happened to check back in here. I’ll take a look at getting more heat and angling the head. Will report back. Thanks again!