VR stylus angle VS cutterhead angle

[Dub Bull]

Warum nicht in Lack schneiden, das ist weich und klingt gut?

Beim Schneiden in Vinylchloridrohlinge (anstelle von Apollo-Lacken) sollten VCA und SRA die von Souri bezeichneten sein. Dies liegt daran, dass sich die geometrische VCA in PVC von derjenigen unterscheidet, die benötigt wird, um eine effektive VCA in einem Lackrohling zu ergeben.
Das Kompensationsprinzip für die Flexion des Stifthalters würde jedoch auch dann gelten, wenn das PVC keinen messbaren Rückfederungseffekt hat.

Wenn Sie eine Rille herstellen möchten, die mit einer guten Kompatibilität mit Standard-Cartirges wiedergegeben werden kann, sollte der resultierende Abtrieb des Schnitts immer noch 20 Grad betragen (VCA), aber wenn der PVC-Rohling überhaupt nicht zurückspringt, dann ist der geometrische VCA von 25 Grad sollte den Effekt einer 20-Grad-VCA-Rille erzeugen.

Der Stiftwinkel zum Lackschneiden beträgt nicht 20 Grad. Diese Anzahl von Graden ist die VCA, die durch den Schneidkopf.

Freundliche Grüße,
Pater José

[boogievan]

Oi, Dub Bull, Mann spricht hier Englisch, bitte...

This is what the previous post by Father José says in (American) English:

"...When cutting into vinyl chloride blanks (instead of Apollo varnishes), VCA and SRA should be those designated by Souri. This is because the geometric VCA in PVC differs from that required to provide an effective VCA in a lacquer blank.
However, the compensation principle for the flexion of the stylus holder would also apply - even if the PVC has no measurable rebound effect.

If you want to create a groove that can be reproduced with good compatibility with standard cartridges, the resulting cut should still have a 20-degree VCA, but if the PVC blank does not spring back, then the geometric VCA of 25 degrees should produce the effect of a 20-degree VCA groove.

The rake angle for lacquer cutting is not 20 degrees. This number of degrees is the VCA that passes through the cutting head."



- Tim E.

[Dub Bull]

{Danke, Tim E. Ich dachte ich wäre in Oberammergau.}

sat159p1, you might need to adjust the mounting of the stylus holder (collet) so that when your cutting head is looking down, the stylus is upright. In one of the pictures I saw that you uploaded to the Vinyl Mastering forum, it looks as if the cutting head must be looking up a little for the stylus to be vertical. For wax cuts, this should be the opposite condition. Cutting head looks down, a little, so that the oblique mounting of the collet holds the stylus upright.

Is your cutting head facing the right way? 0; For impressing (often called 'embossing,' though it's really impressing), only, into plastic records, the stylus is rotated so that the mirror is looking the other way, but the cutting head should be looking the normal direction.

If Souri says he wants 98º or something else for PVC cutting, it's quite plausible, since cutting into DMM copper blanks requires a different rake angle (to preclude 'chatter' of the metal blank - and also a bias frequency to facilitate carving into the copper. PVC is somewhere in between the softness of lacquer and hardness of copper. But the groove needs to be played back by a conventional pickup stylus with a cantilever that wants to push the upright (92º) pickup stylus tip down from a 20º vertical tracking angle...

If your cutting head's stylus holding collet deflects a little (due to normal 'flexion'), then the degree of flexion needs to be added to the target of 20º vertical cutting angle. If it only flexes like an Ortofon stylus holder, then you want the cutting head downforce pivot to be 25º. However, if it flexes more like the Westrex stylus holder, then you want the cutting head downforce pivot to be 30º. (Clear as mud, yet?)

Here's a detail with extra arrows from the Nygaard paper, showing the rocking bridge and torque tube designs and how they hold the stylus and what is the vertical cutting angle - which is not the stylus rake angle, but affects that.

Angles_for_wax_cuts.jpg

- Father José

[boogievan]

You mentioned this above, Father, but it's worth repeating that, for cutting into Apollo lacquers (or MDC), the lacquer spring-back takes up an additional ~ 5 degrees from the resulting (i.e., effective) VCA.

So, for plastic cuts, the required geometric vertical cutting angle = ~ 25 degrees (assuming that the collet flexion = 5 degrees and the plastic record spring-back = 0 degrees (i.e. it doesn't spring back) and the target, effective vertical cutting angle is 20 degrees (ref. 1972 standard for stereo groove records).

For lacquer cuts, the required geometric vertical cutting angle = ~ 30 degrees (assuming that the collet flexion = 5 degrees and the lacquer record spring-back = 5 degrees (since it does spring back), so that the target, effective vertical cutting angle of 20 degrees is achieved after compensating for those 10 degrees of inherent loss.


- Tim E.

[sat159p1]

I get it (and really appreciate your effort to write about it! thanks!) but unfortunately I can't modify the stylus holder. This is so delicate that I don't want to mess with it.
I'm cutting plastic. For me there are 2 ways, in general, like on the picture...

[Dub Bull]

In the videos I've just watched, showing different VR machines making cuts, it appears that they are all like the configuration you drew on the left side of your image. Also dann, just do it that way - and try to cut with the stylus, upright...

In these videos, his vinyl cutting head looks up a little during cutting, whereas, for lacquer cutting heads, they look mostly flat (Westrex and Corinth), or they are looking down (e.g., DSS 821), but the stylus is always (nearly) upright.

Maybe, even though the cutting head looks up a little, the _pivot_ of the VR yoke still makes the cut achieve the (effective) 20 degree VCA.

If the sound is good, then the sound is good.

Viel Glück...


- Father José

[boogievan]

I can see, Father, why you'd be inclined to go with the drawing he put on the left if you were looking at images such as:



or the VinylRecorder U2be channel's image, here:

...making the cut, seen from that camera angle, it looks as if it's 'looking up,' a little, too.

However, from the side-view, close-up camera angles, during the lift condition of the yoke, notice how the cutting head is flat when the stylus is still in the air.

...and how much the stylus is 'looking back.'


...and when it drops, making the stylus enter the land...

...the cutting head 'looks down,' while the stylus is giving plow...

Maybe the OP has more styus rake than normal on his VR-CH, but these images show the basic idea that the cutting head can be parallel to the workpiece, however, that's when it's still a little bit in the air. When it makes contact with the record, it should look down, unless it's supposed to be different from the VR cutter shown in the images from their channel...


...also, the VR holds the stylus for strong plowing into the vinyl. The diamond can take it. It's almost like DMM.




- Tim E.

[Tremdall]

How can one ever trust these photo's since they're all shot from different angles and never exactly parallel to the cuttinghead (from the side). There is always a warp / distortion in the picture with cheap camera's like Iphones and such. This is no reference.

[Dub Bull]

How can one ever trust these photos...

First, please be advised that cutting into plastic and metal is not recommended using the lacquer-specific VCA and SRA. You will need to be plowing more when cutting into disks with plastic memory (such as PVC or a copper phase). Also, you won't need to compensate for the vertical cutting angle as much as with lacquer, either.

Since the plastic blank wouldn't have the elastic memory of a lacquer, it would not require that the spring-back effect be taken into account for one to achieve a groove that resulted in an _effective_ vertical cutting angle of 20 degrees (by adding an additional 5 degrees for groove-wall spring-back). Still, the geometrical VCA will not be easily identifiable from a (cropped) profile picture when the cutting head has a significant horizontal dimension, such as the Westrex types (i.e., T-560), since its pivot point will be far enough behind it that the cutting head may look as if it's parallel, but the solenoid-delivered down-force is coming from something based on the desired 20-degree vertical tracking angle (since it's standard).

It could very well be, however, that the stylus holding collet's flexion, when cutting, does have to be factored in, provided one wanted to make a groove that matches the geometrical orientation and compliances of a standard stereo playback cartridge. If the diamond shank-holding collet's flexion is 5 degrees, such as the corundum shank-holding collet's flexion, then the plastic workpiece's geometrical VCA should be approximately 25 degrees for its effective VCA to result in the 20-degree target VTA. Again, a picture of this type of block-head will not clearly show the VCA (but that SRA is unmistakably acute).


So, being a truth-seeker, first, and kind person, second, I respectfully disagree with some of Tim E.'s vagabond remarks (were you in your boogievan when you posted this?) and find that the pictures of the T-560 cutting head (the two close-ups) that he posted on October 22, showing the stylus still lifted in the air and then dropped into the moving plastic blank can be studied to ascertain that the sight-line of the blank record and the sight-line of the cutting head are nearly-to-very parallel when the stylus is lowered for cutting, and when the T-560 is lifted, just above the workpiece (surface), it seems to be 'looking up,' which is not seen on lacquer-cutting heads. But this analysis matches the careful image taken and shared by MyShank (with compliments).



('looking up?')


(rather 'parallel' - watch that plow)


(MyShanks a lot!)

...so, yeah, the angle of the dangle is easily conflated with pictures that don't show the platter edge, clearly, but the image from MyShank shows that the body of the cutting head is parallel to the workpiece when the stylus has entered the land and the cutting stylus rake angle is rather acute, compared to when in a lacquer-cutting head's collet.


- Father José

[boogievan]

I'll not gainsay your astute comments, Foxtrot-Juliette, though churlishly cheeky. I'm giving myself a free pass on what I posted, and you should, too:


http://www.dataasylum.com/bioapi-nanotech-implants.html


- Tim E.