I was just reading the build thread for the swiss mak and noticed he is using box ways with a polymer insert. I've been considering taking my spare parts from my previous machine builds and building a dedicated pcb mill. Wondering what people think of using this type (delrin/hdpa on aluminum) of box ways for this application and how best to keep the grit out of them? I may just do the box ways for the Z axis since I only need about an inch of travel. i have some sbr12 rails I can use for the other axis.

My machine build is likely going to have the following:

200x200x30 or 200x150x30 working area in x,y,z

500 w brushless spindle with crappy deep groove ball bearings, seems to mill a pcb ok.

nema17 motors and 2gt belts 0.9 degree and 27 oz/in. I also have 3 nema 23 200oz/in motors I can use if the nema 17 motors are too wimpy.