Hello,

I would like to build a CNC router with a dimension of 4 foot (x-axis) x 7 foot (y-axis). For the Z-axis I'm assuming maybe 1 foot of travel would be fine.

It needs to be a precision based CNC router, with tolerances of accuracy and repeatability of at least 50-100 Microns range (0.002" to 0.004").
Care about accuracy more than repeatability.

From my research it seems ballscrews is out from the question because the Y-axis ball screws are no good at that length. Rack and pinion would make more sense. In this time era rack and pinion are very accurate and can hold tolerances I need. Not sure where to buy them from.

Would like to build the CNC bed in a budget friendly manner, so planning to go with UHPC but not sure if it would hold tolerances in the long run as compared to epoxy granite.

So question is, UHPC is a good idea for CNC router machine bed I have in plan?
What kind of linear rails would be suffice and how I would go about in calibrating it of making it straight and parallel?

Will use the CNC router to do fine art details of 3D carvings/engravings on wood to make chairs, tables, doors and etc.

Any advice would be appreciated, Thanks.