I decided to upgrade my printer to M5 rods for a few reasons: Finer thread pitch Same diameter as stepper shafts = easier to align rod properly Less friction because of the smaller diameter rod Rod is flexible so it doesn't shake the carriage if it is bent The first step was to print out a nut adapter: The nut is pressed in and then superglued into place. I had purchased some 5mm x 5mm couplers, but they were either poor quality or the rod was slightly undersized and was making it impossible to center. So I picked up a piece of vinyl tubing at the hardware store and used it as a coupler (with a bb in between the stepper and the rod): The tubing is very snug over the rod and shaft, but to be safe I tightened it down with some zip ties. The final step was to reflash the firmware with the Z axis steps being turned to 4000. With the steps at 4000, I also had to turn down the Z acceleration setting to 50 because at 4000 steps it had to turn much faster to move the same amount, and was tripping the acceleration limit. And here is a nice print showing the end result: I am very happy with the results, especially for a very low-tech solution with the tubing and zip ties. I don't think it could get much better at all. If anyone is interested I can put up the file for the nut adapter on thingiverse.