This contraption?

[Davide Sora]

9 hours ago, Marty Kasprzyk said:

Is there any experimental  evidence which shows that a nice symmetrical graduation contour pattern helps the sound quality?

No, and I would be surprised if there was

[Don Noon]

First, you need to find a sound quality measuring device that everyone agrees is correct and repeatable.  HA!

[JacksonMaberry]

13 hours ago, Michael_Molnar said:

Then I “graduated” to a CNC.

Love it, Mike. 

[JacksonMaberry]

I don't use anything like these tools, but I like Davide's the most by far. KISS approach, and his point about keeping things orthogonal with the entire lower arm as a large, flat "anvil" surface makes great sense. Of course this wouldn't work for the "inside first" cats but I'm sure they have their own tricks.

[Don Noon]

25 minutes ago, JacksonMaberry said:

Of course this wouldn't work for the "inside first" cats but I'm sure they have their own tricks.

A flat table and a "marking height gage" would work for inside first, outside first, or even CNC if one felt any need for checking CNC symmetry.

Or you could use a thin-ish, flat board to put on the bottom of the plate, and use a thickness gage.

[JacksonMaberry]

23 minutes ago, Don Noon said:

A flat table and a "marking height gage" would work for inside first, outside first, or even CNC if one felt any need for checking CNC symmetry.

Or you could use a thin-ish, flat board to put on the bottom of the plate, and use a thickness gage.

True! Haven't spent any time on that puzzle, I'm not convinced it has any special merit