Intro
The below details fixing a floor standing fan that I was given because it was broken with a cascading failure: Initially, the nut holding the fan on the threaded motor shaft stripped. Since the fan blade was no longer held tight, the pin used to drive the rear of the fan blade widened and eventually destroyed the slot.
The Fix
The replacement nut was designed in Fusion and 3D printed. By fine tuning the diameter of the center hole allowed the threads to be formed by simply screwing the nut on, which lead to a surprisingly robust attachment. Larger knurling was included to increase grip while forming the threads.
The fan blade was originally designed to be driven by a pin in the motor shaft and a slot formed in the fan blade. Since the slot was completely broken off, an adapter was designed and 3D printed to drive the fan blade by interfacing with the ribs on the backside.
The design in Fusion takes advantage of parameters to easily make iterative changes to the fitment of parts without having to navigate the model tree.
It was fulfilling to know I gave this fan new life and I’m also happy to know it’s not going to the landfill in a day where disposable items are too common.
The 3D files are available on Printables: https://www.printables.com/model/1790790-pedestal-fan-nut-drive-adapter
Design Iterations
The above design was certainly not the first version. Initially, the design started with a test fit piece to get the bore diameter dialed in.
The initial design intent was to use the backside of the nut to mate with the front fan face, but minor misalignment of the formed threads caused run-out of the fan blades. Instead, the design was changed to instead mate the drive adapter face which has a tight fit to the motor shaft, and only press on the front fan at a small radius as to not influence the alignment. Of course, this part immediately broke since since I didn’t support the cylindrical extension on the back of the nut. Finally, a large chamfer was added to strengthen the part and allow for less support material when printed.
