For the z-axis, i want to move the knee. I'm not a fan of quill drives and i'd like to keep the quill for manual stuff. I'm thinking about the homeshopcnc 2500oz/in stepper and another g201 drive. The current should be under the g201's rating and it should have enough power to move the knee with a reasonable rapid. The only thing that concerns me is the backlash in the bevel gears in the knee. The weight of the knee should keep the backlash out of the screw but i'm not sure about the gears. Hopefully you experienced folk will chime in here.