The part on the last phote is the motor for the Z axis including the bearing holder block. on this photo you can see the complete machine so far.
A very luxury feature. I didn't known, that this is necessary. (One time in a year before x-mas-holiday seems to be enought. ). In my last job we used machines for testing semiconductor-wafer. => wafer-prober. The service of the company checked and "oiled" the ball bearing spindel only every year. Okay, to move a semiconductor wafer or to mill the steel needs another power....oil groves for X and Y axis