Original Prusa i3 MK2 Z-Axis Clip on Fan Mount

thingiverse

After completing my first 8+ hour print, I noticed how hot the stepper motors were getting. I discovered several excellent examples for mounting 40mm fans to Nema 17 stepper motors. The Z-Axis motors still get plenty of exercise and heat up quickly, especially on objects with intricate details or when printing at higher speeds. However, I never found any specific designs tailored to the Z-Axis motors found in the original Prusa i3 MK2. I was inspired by other innovative designs, mainly: https://www.thingiverse.com/thing:1409754 -and- https://www.thingiverse.com/thing:31405 ...but neither of these would fit the Z-axis. The Original Prusa i3 MK2 and MK2S have unique brackets that hold the Z-Axis stepper motors, but also prevent full wrap-around designs. My objectives for this design were twofold: 1. Design a bracket that mounts easily without requiring disassembly of any printer components. Disassembling could result in recalibration, which no one has time for. 2. Design a bracket that effectively cools the motor while deflecting air down and away from the heated print bed. To meet these goals, this fan mount is a clip-on design that simply slides onto the Nema 17 motor's own grooves. The walls are thin (1mm) to allow plastic flexibility and fit around the motor while providing air channels that help cool the sides and deflect air downwards. You must print two of these mounts, one for each Z-Axis motor on the Original Prusa i3 MK2. The left and right side motor mounts are identical, so my design works on both. The screw holes are sized to fit M3 screws and will self-thread into the plastic. Purchase screws 5mm longer than your fan's thickness. For example, to mount a 40mm x 20mm fan (like the one in my pictures), you will need M3 x 25mm screws. If your fan has countersunk holes, get 5mm shorter screws. You can always use a small washer if needed. If your screws are too long, they WILL prevent the mount from fitting onto the motor properly. Nuts and lock washers are NOT necessary to mount the fan. If you do use nuts, take care to use ones thinner than 5mm. I used the recommended settings for the Prusa's version of Slic3r included with the printer. Specifically, .15 resolution, 20% infill, and no supports or rafts. Mine are printed in PLA, but feel free to attempt printing them using other materials. This fan mount may work on other printers with Nema 17 stepper motors, but it was specifically designed for the Original Prusa i3 MK2 and MK2S, and I do not guarantee compatibility with others. Prusa has recently announced the MK3 for release later this year. Based on the pictures, the Z-axis motor mounts appear unchanged from the MK2 series, so I strongly suspect these might fit the MK3 when it comes out. If it doesn't fit the MK3, feel free to remix it.