Acrylic platter

Nandric.

I agree, there is an art in operating the CNC machines.
In our CAD/CAM shop, different operators produce different "quality" even though they are using the same program. Figure that.
I have dynamically balanced my composite platter by removing a few grams.
The MK3 is good, but the motor and that of its little brother, the MK2, can be made much better :-).
There are many contenders for the "best" and in the end it largely depends upon personal preference. One man's poison and all that.

Dear Richard, ''different operators produce different 'quality' even thought they are using the same program.'' Lew is better equiped for this domain of knowledge but a big part of the frontal lobe 'govern' our hands. Every single person who has seen Michelangelo's
David or Pieta has difficulty to believe that those are made by human hands. And he (1475-1565) had only chisels and hammers to his disposal. Back then the church was the
most important 'pricipal' while the church authorities were capable to select the 'best workers' available to build and decorate their churches. We use the word 'talent' to express or explain the differences in 'quality' which you also mentioned. However 'talent' is probably the gift of the 'mother nature' but the fact is also that without practice no mastership is possible. Because of the division of labour many of us are not even able to use an hamer in a proper way despite the constitution of our frontal lobe.

Addendum for Richard. You may be interested to know that
physicist designer David Fletcher and the master machinist
Demian Davidson produced togehter the so called 'The arm',
'The better Breuer' or simply the Sumiko 800 tonearam.
This tonearm is handcrafted from 160 different parts and was
provided with 6 different counterweights. For the carts
from 6 g till 22 g. Those weights are sold depending from
the cart which customers owned. So the most Sumiko owners
have just one weight. I made much effort to complete my
weights and even assisted 'my machinist' by the production of the
missed 4 weights. My job was to measure each one and raport
how many grams needed to be cut of. I was very careful not
to cross the 2 meter border line to the 'monster'
(aka the CNC lathe). Now I think that I am the only person
who owns an complete Sumiko 800 with all the weights.
To my mind this one as well as the FR-64s and the
Triplanar are the real works of art.

Nandric, I may be wrong, but I think Richard is saying that different operators produce different quality results, even though the machine itself is computer-controlled, and presumably even though the program being used to control the computer may be the same for each operator. I share Richard's puzzlement, in that case. There are still some hands-on aspects of the work, including fixing the blank piece of metal into the cutting machine, and perhaps therein lies the source of the variable outcome.

Nandric and Lewm.
I have seen both David and Pieta and I was in awe at such beauty, such craftsmanship. Made from stone no less!

I remember The Arm, way back then I lusted after it, which was irrational since I never actually auditioned one properly. (Is one allowed to use the term lust in these PC days (daze)). But with my tiny take home pay, ownership was never going to happen. Even then it was hideously expensive here but this price was probably justified given that it was obviously made with great care by craftsmen.

Lewm, you are correct. Same program, same machine, same material, different result. And yes it is likely work piece set up, vice tension and all the other tiny "insignificant" little things that make the difference.