Prusa MK3, MK2S X-Axis Belt Tensioner

thingiverse

I encountered significant difficulty when attempting to achieve the desired belt tension on my MK3 printer while assembling it. The limited adjustability provided by rotating the stepper motor during tightening was not sufficient for my needs. Furthermore, once assembled, accessing and tightening the belt on the X-Axis carriage proved to be a challenging task. To address this issue, I designed a simple yet effective plate that mounts directly onto the motor, featuring slots that allow for easy belt tightening. To assemble this plate, four M3 x 10mm screws are used to secure it to the X-Axis motor, which I happened to have readily available in my Spare Parts Bag. Next, three square M3 nuts are installed within the slots of the plate, and then the mount is assembled, leaving the screws slightly loose. A screwdriver is inserted between the motor and the frame for leverage, allowing me to tighten the belt effectively before fully securing the three screws. To ensure proper alignment, I rotated the pulley on the motor by 180 degrees so that the belt was positioned within the slot. This modification proved to be a crucial step in achieving optimal belt tension. Update: On January 22, 2018, one user who had successfully created this mod for their MK3 printer required an increase in the center diameter to 1.0in to accommodate their stepper motor, which has a center locating diameter of 22mm. To address this need, I designed and added a second bracket with a 1in center diameter, making it available for anyone who may encounter the same issue. Update: As of October 30, 2018, I was informed that this mod is not compatible with the new MK3 built-in X-Tensioner design. Unfortunately, this means users cannot utilize both features simultaneously at this time.