Now that my KRMx02 is tuned up and making chips, I thought I'd start to document some of the upgrades I've made.
The image below shows the Z-Axis constant-force spring I installed. The Z-Axis assembly weighs a bit over 22 pounds, so to help equalize the forces on the lead screw I installed a 9 pound-force, 25,000 cycle constant-force spring that I got from McMaster-Carr. The front of the spring bracket will hold the vacuum hose, as well as the coolant and air lines for the mist coolant system I built for $20 (which I'll document some other time). In the photo, the vacuum hose is off to the side for clarity. I built the 'tower' from 3/4" x 1/8" angle stock I had handy, plus a bracket for the spring end from 1-1/4" x 1/16" stock. The angle stock wraps around the extended Z carriage for good stability. There is some adhesive felt on the Z extrusion to prevent the spring from rubbing the aluminum - it s black and just barely visible. Also note how the router power cord is routed.
The result is that the Z-Axis is more difficult to push down by hand (power off) and the motor noise is more symmetrical up and down.
PM me with any questions.