Motor Cooling Fan V3 - Press Fit with Spring Hub

prusaprinters

<p>To use this print you will likely need to start with the original CAD file, in order to adjust the parameters to fit your particular motor (another possibility is to scale the included files). The included PDF file shows the dimensions for this print; all of the dimensions shown can be modified in the parametric CAD file. In particular, the hub ID needs to be small enough so that it makes a tight press fit onto the motor shaft, but not so tight that the hub cracks. This version incorporates a new hub design to help address that issue.</p><p>The hub ID for the included print is 19.6mm (nominal); note the internal part of the hub is octagonal, so this “ID” is actually the dimension across the flats.. See the included PDF file for other dimensions.</p><p>This fan was created as a replacement for a broken electric motor cooling fan (see photos for V1 of this fan). The original fan was press-fitted onto a splined shaft (see photo), and this print was dimensioned to fit that shaft and motor.</p><p>This print is a remix of some earlier prints I made. In part this was to adjust some dimensions I was able to measure once I received the broken fan this was designed to replace. The other major change was a new hub design which I am calling a “spring hub.”</p><p>The “spring hub” is a one-filament-layer thick octagon withing the ID of the hub. &nbsp;When pressed onto a motor shaft, the side of the octagon “spring out” so that the hub is gripped firmly without transmitting stress the rest of the hub so as to cause cracking (at least that is my theory). The hub ID still needs to be sized to fit a particular shaft OD, but I believe this design accommodates greater tolerances and so is more forgiving.</p><p>See Version 2 of this print for more suggestions on determining hub fit. Note that this fan is slightly smaller than the V2 version.</p><h4>Print Instructions</h4><p>I printed in PETG on a textured build plate. This might work in PLA, but that would not be my first choice. Since this part is a press fit, the plastic used needs to have some “stretch” (nylon would probably be a good choice as well, but I do not have any of that). All pieces were printed with 0.2mm layer height, with concentric top and bottom fill pattern.</p><p>I added extra perimeters for strength, but opted not to create a solid hub so as to permit some flexibility. I used 25% rectilinear infill overall.</p><h4>CAD</h4><p>The OnShape 3D CAD files for this are here :</p><p><a href="https://cad.onshape.com/documents/81a6e848a3cfe91eb01b2dc1/w/68ab4479d2ff82fec2074759/e/cfbb3b046bcc11f0b2159d28">https://cad.onshape.com/documents/81a6e848a3cfe91eb01b2dc1/w/68ab4479d2ff82fec2074759/e/cfbb3b046bcc11f0b2159d28</a></p><p>&nbsp;</p>