Light marks when cutting with diamond

[crowesBR]

Got some blanks and a diamond stylus and my first cuts have this light marks on the discs.
Have 5 discs and all of them have that after the cut. And is only on one side. The other is ok.
You can see the first track almost at the end.

Do you guys know if this is a blank problem or my cutting? Or is a normal thing?
This is not affecting playback. More a cosmetic thing.

I used some anti static fluid from shank and after the cut I washed the discs.



Thanks
Anderson

[piaptk]

Are you sure that isn't just the modulation pattern for that particular song? I can't really tell exactly what you are talking about.

[crowesBR]

Not a particular song. I have the same song in another disc and looks fine.

I think maybe is my ionizer and vacuum jar that is on the same table as my Presto causing some vibration?

[crowesBR]

Looks like the grooves are not deep enough in one side only but not the full disc. Other is fine.

This one the song 1 is fine and than starts in the middle of song 2.




Cut one side all good. Cut the other happens this.
Tried 5 discs. All have the same effect. One side is good, other side not.


Any help?

[crowesBR]

Ok. I think I figure it out.

Looks like the discs from shank were not completely flat.
So I added some tape and the right temperature. Voila.

Hope the next batch will be ok.

[crowesBR]

Nah.
One side only.
Next 5 same thing.

What is going wrong?
Looks like sometimes my groove is deep enough and sometime barely touch the disc.

Anyone cutting with diamond on Presto 6N?
How is your experience?

Now that I setup the vacuum and all works well this happens.

Maybe I'll need a heating stylus instead of lamp? 99.99% that is not the issue. But who knows?

Frustrating.

Maybe Presto's was not to be cutting with diamonds on 12"?

[Jccc]

have you checked to see if the feedscrew is fully mounted in?


i remember my 6n was having weird grooves and it driving me crazy and i remembered i changed the feedscrews awhile back and i looked surely the screw was not fully mounted.

or some dirt may have got inside the grooves of the screw causing it lift up in that area?

Maybe check the spring that adjust the depth maybe its getting caught on something?

[crowesBR]

Yup. Checked that.
I made a few cuts with lacquer and looks/sounds good. No problem at all.
Same feedscrew and sapphire. Cut a 12" both sides and no problem. All looks ok.
When I use a diamond and shank blanks have some weird grooves. Using heat lamp 90 degress consistant. Measuring every second.
First 6 minutes looks great and than starts to get weird. Shallow grooves. Don't think is static.
Vacuum get all the chip. Using dashpot and measuring pressure.

Cleaned all feedscrews, used some other ones, taped all blanks and not sure whats going on.

Maybe the machine is off and can handle 12" with diamond and shank? Don't think.

Didn't tried with 10 or 7 "

But don't thing that will help.


Weird.

[aaron]

It seems to me that you may have some vertical oscillation.. Especially if the groove depth is changing. Maybe check that your dashpot is adjusted correctly..?

[sat159p1]

Or maybe a mastering of the song, phase issue "disappearing groove effect" or something?

BTW, I got these "marks" when cutting with a diamond when the song had a lot of loud hi-hats for example (electronic hi hats with sharp attack). I thought it was bad but it was just hi hats that made the marks. Visible on 33rpm, not visible on 45rpm. Sound is OK in both cases.

A.

[aaron]

But it looks like it's spread across two tracks, on the same section of disc...

[crowesBR]

Yeah. Dashpot is good.

[crowesBR]

OK. Looks like was my vacuum tube that was really close to the disc.

Now all good.

Thanks all