Motor Cooling Fan V2 - Press Fit

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.</p><p>The hub ID for the included print is 19.0mm (nominal); about 18.9mm actual. 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). 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 an earlier print I made. &nbsp;I think this version offers these improvements over the previous version:</p><ul><li>Improved ease of printing - the hub can extend from the fan on both the top and bottom</li><li>Improved ease of fitting - the hub pieces can be printed separately (and faster and cheaper) than the entire fan, making test fitting easier</li></ul><h4>Determining the Fit</h4><p>I made a number of test prints to determine the best hub ID for a given fan. The first thing to keep in mind is that the nominal hub ID is a bit larger than the actual printed hub ID. Here are some results I got with my test print:</p><figure class="table"><table><tbody><tr><td colspan="3">Hub ID (mm)</td></tr><tr><td><strong>NOMINAL</strong></td><td>&nbsp;</td><td><strong>ACTUAL</strong></td></tr><tr><td>18.0</td><td>&nbsp;</td><td>17.8</td></tr><tr><td>18.9</td><td>&nbsp;</td><td>18.7</td></tr><tr><td>19.0</td><td>&nbsp;</td><td>18.9</td></tr><tr><td>19.6</td><td>&nbsp;</td><td>19.4</td></tr></tbody></table></figure><p>With the above in mind, I found that an actual ID which is 0.1-02mm smaller than the OD of the shaft onto which the fan is being press fitted. Because there is some trial and error involved in finding the best fit, I have included a test print which can be used to test fit without having to print the whole fan.</p><p>In the photos, you will see the “test shaft” I made to test the prints, and a view of one of the test prints mounted on the shaft.</p><p>&nbsp;</p><h4>Assembly</h4><p>Assemble the pieces as shown in the exploded view. &nbsp;If you look closely at the photo of my test print, you will see that there was some chipping on the assembled piece. &nbsp;This happened because I used a “soft” hammer to force the pieces together. What I should have done is used a clamp with some padding to make sure the pieces were fully engaged.&nbsp;</p><p>The pieces hold together very well without the use of glue. However, I recommend using some CA glue on the assembled pieces just to make sure that vibrations do not lossen the pieces in use.</p><p>&nbsp;</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>If you look at the 3mf file, you will see that I used a large enough number of perimeters for the hub to create solid pieces.&nbsp;</p><p>For the fan piece, I used rectilinear infill. It is important that any infill used be uniform so that the fan will be balanced. I used a cylindrical modifier to add perimeters to the center of the fan piece, so that the section under the hub was solid. The complete fan print took about 4-½ hours to print.</p><p>&nbsp;</p><p>&nbsp;</p><h4>CAD</h4><p>The OnShape parametric 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>