Prusa spool holder (with bearings)

prusaprinters

<p>Centering spool holder with 608 bearings to be used with the original spool holder for the Prusa MK3S+.</p><p>I have some TPU which sticks quite well to itself so I needed a spool holder which allows for super-smooth rotation so the filament peals off easily - I tried some others, they did not work as expected.<br>&nbsp;</p><p><strong>Design:</strong></p><p>Fits spools up to (roughly) 75mm in width given a 55mm inner diameter. Depending on the printed nuts the maximum inner diameter is 60mm or 80mm (see STL file names).</p><p>I made the two pins as separate parts for two reasons:</p><ol><li>Stability: If they are printed lying horizontal on the bed there is (imho) less chance of layer separation while in use</li><li>Printability: No supports needed for the base part (or any other part)</li></ol><p>The M3 screw connects the base part with the bearings and also increases the overall stability of the base part. The M3 nut secures both the screw and the pins.<br>&nbsp;</p><p><strong>Update 13.07.2021</strong>: Added chamfers to all nuts and bolts.</p><p><strong>Assembly:</strong></p><blockquote><p>See the comments section for how others solved the assembly problem. Feel free to share your own solution!</p></blockquote><p>You need two 608 bearings one M3x30 socket cap hex screw, and one M3 hex nut.</p><p>You need to slide the two pins and the M3 hex nut into the base part all at the same time. This can be a bit wearisome. Here is how I assembled the base part, see the last 5 pictures labeled STEP1-5.</p><ol><li>Partly slide the two pins into the base such that the slots for the M3 nut are level with the top of the base part.</li><li>Use a plier to push the M3 nut into position, this may require some attempts.</li><li>The base part should now look like in STEP 3, make sure the M3 nut is properly aligned.</li><li>Turn the base upside-down and press the part against the table. This may require some force, but the pins should slide in just fine.</li><li>You are done, great!</li></ol><p>Attach the base part to the Prusa spool holder using the screwdriver before you attach the threaded rod, otherwise it's going to be a bit difficult ;)</p><p>See the labeled cross section rendering for details.</p><blockquote><p>Initially I used <a href="https://www.amazon.de/gp/product/B076T5MQW8/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&amp;th=1)">hybrid ceramic bearings</a> for the rolls to run smoothly but when using really flexible filament (shore 30D) on an out-of-balance spool the filament partially unrolled itself over time. Fixed it by using <a href="https://www.skf.com/group/products/rolling-bearings/ball-bearings/deep-groove-ball-bearings/productid-608-2RSH">SKF 608-2RSH</a> bearings but I assume using any cheap 608-2RS bearings will do.</p></blockquote><p><br><strong>Print:</strong></p><p>Use your slicer to get the individual parts.&nbsp;</p><p>Printed all in PETG with 4 perimeters, looks good so far. The base part and the pins are printed with 100% infill. Use 0.15mm layer height to get nice threads. To get less noticable seams set random seam position.</p><p>&nbsp;</p><blockquote><p>Please leave a comment or a photo if you print it!</p></blockquote>