Originally Posted by
Mountaincraft
You know, once you build your table and it has all it's parts on it, and everything is tightened down, typically, most people install a sacrifice board and then use the machine to mill itself... If there's little play in everything, then the surface job should follow any imperfections, so that when a material is secured 'flat' to the sacrifice board, you can get some pretty tight tolerances, as your machine calibrated itself to account fro any imperfections..
I don't know for sure about this, but wouldn't most materials expand and shrink with temp changes to exceed the .001 tolerance your after? I would that the CNC table would.. and the larger the size of the table or material, the more the total expansion and contraction, no? Or are you going to have a climate controlled environment?
When I have mine milled, I'm not after any specific 'tolerance' on the table itself so much as making the thing move as smooth as possible... I just want it as parallel as is reasonable... as every 'error' gets added to the next error during assembly.. So the more critical I am in the early stages, the more forgiving later stages will be.. I'm also very interested in mass and solid construction so that I can push it at higher speeds...