is it possible to achieve a perfect polishing on granite or marble with a CNC-machine or are you guys have to touch up the polishing by hand?

Thanks in advance

byebye

Juergen

In my personal opinion there is no way a CNC will make a perfect polish. Any machined polish will leave lines. I've heard glory stories about how "this" tool or "that" tool wont leave the lines but I simply dont believe it. Granted you may have smaller lines that are less noticable but ultimately, they are still there. Nothing beats polishing the stone by hand, its craftsmanship, its an art. Theres nothing bad about the CNC polish, in fact, I did the kitchen and vanities in my own house on our CNC and I have no complaints whatsoever. Theres a definate noticable difference, but you have to be pretty anal about it to pitch a fuss.

If you are that worried about it then simply have someone run a hand polish over the work the CNC has done, or do that from the beginning and save your machine time.

Amateur telescope makers were frequently warned about 'zoning' caused by machine polishing their telescope mirrors. The trouble with a machine is that the repetition of a stroke is too perfect. Build a machine (or a program) that introduces a degree of randomized stroke length, randomized direction and inexact rotation of the lap, and you might have half a chance at getting a good job off of a machine.

I don't know if that applies to general polishing such as you need, but the underlying principle is likely the same.

techniqiue and tooling....I promise it is possible some machinesa are made for it!

There are some edges that you can polish with no lines. Flat (Z) profile on some machines (CMS Brembana machines will do this) can be osolated on the cnc to take out the lines. It also depends of course on the stone and the profile as to how the lines stand out. More complex profiles (ex. triple pencil) it is hard to see the lines. I put Santa Cecelia in my kitchen with a triple pencil edge, cut it on the machine, sealed it, and installed it without touching a hand grinder. It is possible. Also if you take care of your tools (keeping them dressed and calibrated) the lines can be left at a minimum.

Hope this helps,

Paul