Cutting cds

[VRCM]

I have made a small advancement in the cutting of cds. After spending an entire afternoon running around scratching every material I could find with a needle, I found that with cd plastic, it works better when you turn the needle around. Instead of cutting you sort of press in a groove. It works surprisingly well. Although, you need to be careful that you do not put too much weight on the head because if it does start to cut the plastic it will create a lot of background noise. The sound has a bassy sound to it, but there is very little background noise.

[RVonse]

Have you tried heat to the stylus yet? I'm just thinking heat might help groove down further into the plastic without making more background noise.

I would imagine that your end result on cd plastic will last longer than a standard acetate dub.

[VRCM]

No. That is my next project. That is a good idea though; it would probably get rid of a lot of that "bassyness."

[buckettovsissors]

Hi,
Yea this is exactly what I do, turn the needle around.
It works well ,no swarf and the groove is deep enough.

I have tried the same thing with other plastics but it doesnt seem to help.

[VRCM]

Yeah it is even deep enough to scratch with and the fidelity holds up well after a lot of playing. The only problem that I am having now is that my new head is lower than the old one. Because there is the flange that locks onto the middle of the platter as you cut to turn the lead screw, my head cannot cut over the flange like I did with the old head. Before I was able to get a couple minutes or so on the cd at 33 1/3 but now I get only a 1/4 in or so of groove.

[tape]

I have succesfully embossed all kinds of thin plastic using an old rounded pickup needle. However the pickupneedle can not emboss cd's properly.

When I try to turn an ordinary cutting needle around, I can not cut plastic - it simply rips it up. Im using an unheated saphire.
I can't emboss cd's either - they got ripped even on the lowest weight on the cuttinghead possible. When I adjust the depth I get either ripping or 'scraping' when the needle only touches the plastic ocasionally.

Any suggestions will be highly welcomed.....

(As far as I know embossing require a somewhat dulled cutting stylus, and a correct angle)

[VRCM]

Well I used an old steel cutting needle also unheated. I do not know if that would make a difference. That is funny because I was able to lay all of the weight on the cd with out scratching or scrapping. Maybe your saphire is not dull enough.

Plus, to be specific, I am using old aol cds and other software discs. I do not think that that should really affect things though.

[tape]

thanks for the tips.
The trick must be the dullness/roundness of the stylus.
For embossing plastic, I use this old pickup:


It's hard to see what the tip is made of - could be steel, could be diamond...
It looks very much like a Soundscriber needle.
My guess is that a ordinary steel-cuttingneedle has to be dulled a LOT, otherwise it will scrape the plastic.

It works really good, but the shallowness of the grooves makes tracking/playback on a modern turntable very hard.

[VRCM]

Also the angle could be a factor. Try leaning it back if you can.

[tape]

Fiddling with the angle did the trick - thanks.
However, embossing dont give the same level or frequency response as normal cutting. It's much lower and there is less treble.
I suspect this has more to do with the technique itslef, rather than the type of neede/ cutterhead.

But maybe some of you are having other experiences?

[VRCM]

I have the same thing. The recording is clear but low and muffled sounding. I do not know if heating would help. That is something I have not gotten into yet.

[cuttercollector]

It would stand to reason that embossing would not lend itself to recording the smallest high frequency information, as you are really just deforming material or pushing it out of the way to make the groove. The smallest features probably just "spring back" or average out to some degree rather than forming the small details necessary.

[tape]

I am afraid that you are right. Could be fun though, to get better quality with embossing. It's interesting for many obvious reasons.

I have tried embossing with a small portable Soundscriber, a sewing needle (!) and the pickup pictures a few posts above. All with nearly the same results. A little better on the Soundscriber machine itslef, but that is probably because it's aligned perfect in terms of angle/weight.

The material semms to produce identical results as well - not much difference there. But maybe with heating can improve things...

[tape]

btw: could anybody here identify this pickup stylus: (not the cartridge)


Im looking for some more of this kind.
It's hard to see on the picture, but the stylus has a bended shape, a sharp (diamond?) tip, attached to a round 'ball'

thanks

[markrob]

It would stand to reason that embossing would not lend itself to recording the smallest high frequency information, as you are really just deforming material or pushing it out of the way to make the groove. The smallest features probably just "spring back" or average out to some degree rather than forming the small details necessary.

Hi,

I'm interested in this form of recording. I had not given much attention to this until I created an embossing sytlus by accident when trying to record on Lexan sheets. Then last weekend, I was at a flea market and found a SoundScriber for $5. I pulled the head off and attached it to my homebrew lathe. So now I'm hooked.

I've been doing some reasearch on this method. I found a 1947 paper titled "Sound Embossing at the High Frequencies" by Milton Morse. It appeared in the Journal of the Acoustical Society of America Vol 19, Number 1, Page 169. What he shows is that the limiting factor is the geometry of the embossing stylus and linear record speed. The major difference between a chisel point cutter and an embossing stylus is theat the embossing stylus is conical and essentially creates a groove that is constructed as a series of circles. He shows that with this method, there is a critical point that is reached dependent on the radius of the stylus, wavelength of the audio, and amplitude of the audio. When this point is reached, the groove is widened and and the playback stylus reads this an amplitude decrease. The effect is opposite of the pinch effect with a traditional cutting arrangement. I'm still digesting the fine details of the paper, but it has me thinking.

I would post the paper, but I had to pay ($25 ouch!) to get it from Scitation and I believe its under copyright. I'm sure you could find a copy at a good technical library. I think that a different cutter geometry could be developed to greatly improve the results. I suspect that work ended on this technology with the advent of consumer tape recording. In the dictation market, response to 4 or 5K was more than good enough and the process was very robust, so there was no need to go further.

If anyone has addtional technical references, patent numbers, etc. with info on embossing, please post the info.

Mark

[tape]

This is very interesting!
I hope this paper will available online somewhere.

I have found a lot of patents on embossing on freepatents.org + google patents. But none that describes the actual stylus design.
Again, I have sucessfully embossed plastic using sewing and safety needles, but a dedicated stylus are probably better

[cuttercollector]

It would stand to reason that embossing would not lend itself to recording the smallest high frequency information, as you are really just deforming material or pushing it out of the way to make the groove. The smallest features probably just "spring back" or average out to some degree rather than forming the small details necessary.

Hi,

I'm interested in this form of recording. I had not given much attention to this until I created an embossing sytlus by accident when trying to record on Lexan sheets. Then last weekend, I was at a flea market and found a SoundScriber for $5. I pulled the head off and attached it to my homebrew lathe. So now I'm hooked.

I've been doing some reasearch on this method. I found a 1947 paper titled "Sound Embossing at the High Frequencies" by Milton Morse. It appeared in the Journal of the Acoustical Society of America Vol 19, Number 1, Page 169. What he shows is that the limiting factor is the geometry of the embossing stylus and linear record speed. The major difference between a chisel point cutter and an embossing stylus is theat the embossing stylus is conical and essentially creates a groove that is constructed as a series of circles. He shows that with this method, there is a critical point that is reached dependent on the radius of the stylus, wavelength of the audio, and amplitude of the audio. When this point is reached, the groove is widened and and the playback stylus reads this an amplitude decrease. The effect is opposite of the pinch effect with a traditional cutting arrangement. I'm still digesting the fine details of the paper, but it has me thinking.

I would post the paper, but I had to pay ($25 ouch!) to get it from Scitation and I believe its under copyright. I'm sure you could find a copy at a good technical library. I think that a different cutter geometry could be developed to greatly improve the results. I suspect that work ended on this technology with the advent of consumer tape recording. In the dictation market, response to 4 or 5K was more than good enough and the process was very robust, so there was no need to go further.

If anyone has addtional technical references, patent numbers, etc. with info on embossing, please post the info.

Mark

high frequencies in that era was pushing it all the way to 10KHz rather than 5

[markrob]

[/quote]

high frequencies in that era was pushing it all the way to 10KHz rather than 5 [/quote]

I think that's true for cutting, but I don't think embossed recording was going that high. Do you know of any examples?

Mark

[tape]

Could need a bit of advice here:

I have been cutting laser discs, or rather embossing them with an old Soundscriber head, attached to my lathe.

I embossed a whole disc without any problems - there is very little surface noise, and the grooves have a fine depth - no tracking errors on playback. So far so good.

I tried again with an identical disc, and got just screech. The disc surface was eared up. Then tried the usual adjustments: weight and depth, still screech. Then tried another identical disc: still screech no matter what.
Then tried to emboss on the first disc again: no problems at all.
This rules out a dull needle and wrong settings of depth and weight, since the discs are identical.

Any idea what is going on here?
The discs are absolutely identical movie discs and are not warped.
The lathe is perfect leveled, needle is unheated, running 33RPM.

[markrob]

Hi,

Maybe its some sort of resonance effect. Perhaps there is a slight difference in the material between the two discs and the increase in sliding friction and or stiction is exciting a spring mass resonance present in the stylus cantilever. I could envision the stylus transitioning from embossing to cutting in an oscillating manner.

I wonder if either stiffening or adding damping material (e.g. rubber) to the embossing stylus would kill this? What would happen if you were to apply a thin coat of lubircant (say silicone spray) to the surface?

Just some random thoughts.

Mark