Quote Originally Posted by Steel View Post
"By the way were you actually trying to infer that your creation will be capable of holding 0.001mm over a 12 inch disc or did I misunderstand that?". No i was just asking a question if there was a cnc
machine capable of .001mm as I make telescope mirrors for a hobby and i can produce by hand mirrors with a surface accuracy of 0.000125mm so just wondering if a machine could get anywhere near that.
Please explain/show the equipment you use to measure to that level of accuracy.!

Quote Originally Posted by Steel View Post
As to the Axial loads on my z axis can anyone tell me what you think it will be lets say cutting pine at a feed rate of say 700mm pm with a 2 flute 6.35mm end mill and a pass depth of 4mm ? just a approximate estimate will do
It's no that simple. To calculate accurately you need to know the bearing type and arrangment. Also just saying pine isn't enough as there are many species of pine so each will cut differently and be different Density/Dryness.

However I wouldn't worry about the bearings failing, which they will sooner rather than later, because this will be the least of your troubles. Between resonance and the shity engineering they'll hardly be working much.