Creality Ender-3 Y-Axis MGN12H Linear Rail Mod (Older Style)

prusaprinters

<p><i>Note:This is for the older Ender-3 printers with the flat/z-shaped front Y idler bracket. </i><a href="https://www.thingiverse.com/thing:3058382"><i>Here's the mod</i></a><i> for the newer style with the U-shaped front Y idler bracket.</i></p><p><a href="https://www.thingiverse.com/thing:2914034">The original design</a> placed the belt too close to the frame which caused severe belt misalignment. This could be due to my unit being an early model, poor QC or a number of other reasons, so I moved the holes for the belt retainer blocks out 4.6mm.</p><p>I figured I wasn't alone in my endeavor to fix a wobbly bed, so I wanted to make this remix available. A<strong>HUGE</strong> shoutout goes out to <a href="/goopyplastic/about">goopyplastic</a> for doing most of the heavy lifting on this design. Don't forget to degrease your rail &amp; carriage. Pre-lube everything if you want to do it now or save the mess &amp; wait until its mounted.</p><h3>BOM</h3><ul><li>1 x Ender-3</li><li>1 x 300mm MGN12H linear rail</li><li>2 x M4x20mm screws</li><li>2 x M4 t-nuts</li><li>2 x M4 washers</li><li>4 x M3x25mm screws</li><li>16 x M3x8mm screws</li><li>12 x M3 t-nuts</li><li>4 x M3 locknuts</li><li>12 x M3 washers</li></ul><p>Printed parts from Print list below *<i>Optional:</i></p><ul><li><a href="https://tiny-machines-3d.myshopify.com/collections/replacement-parts-for-creality-printers/products/bed-leveling-spring-for-creality-cr-series-3d-printers">4 x CR-10 bed springs</a> to replace stock springs &amp; <a href="https://www.thingiverse.com/thing:2434419">8x spring caps</a></li><li><a href="https://gulfcoast-robotics.com/products/borosilicate-glass-for-the-creality-ender-3-4mm-thick-w-rounded-edges">1 x 235mm borosilicate glass bed</a> &amp; 4 x binder small clips</li></ul><p>1 x yretain.stl @ 0.2mm, 2 shells, 100% infill</p><ul><li>1 x yretain-mirror.stl @ 0.2mm, 2 shells, 100% infill</li><li>1 x ylimitspacer.stl @ 0.2mm, 2 shells, 100% infill</li><li>1 x ydrillguide_remixed.stl @ 0.2mm, 3 shells, 15% infill</li></ul><p>2 x Linear_Rail_alignment_helper<i>MGN12</i>+_V-Slot_2020.stl @ 0.2mm, 3 shells, 15% infill *<i>Optional:</i></p><ul><li>4 x mgn12-rail-stop.stl @ 0.2mm, 2 shells, 100% infill. You'll only need two, but they tend to break if printed with PLA due to the snap on fit. These replace the goofy red stops included with most rails.</li></ul><ol><li>Remove all four bed leveling knobs &amp; lift the heated bed &amp; springs out of the way.</li><li>Loosen the screws on the front idler to give the Y belt some slack &amp; slide the belt off the Y plate. Remove the four screws &amp; v-wheels holding the Y plate to the extrusion.</li><li>Once all hardware is removed from the Y plate, use<strong>ydrillguide_remixed.stl</strong> to drill 1/8" (3.2mm) holes by aligning it in the holes where the v-slot wheels were mounted.<i>Note: There's an additional set of holes for different hole patterns of mgn12 carriages, so check which spacing your carriage has to avoid drilling unnecessary holes.</i> Use larger drill bit or small file to deburr the holes.</li><li>Mount the<strong>yretain.stl</strong> &amp;<strong>yretain-mirror.stl</strong> blocks to the Y plate using 4 x M3x25mm screws, 8 x M3 washers and 4 x M3 locknuts. Pay attention to the orientation of the Y plate as this mod rotates Y plate 180 degrees. Use the pictures for guidance.</li><li>Mount the 300mm MGN12H rail to the extrusion using using 12 x M3x8mm screws and 12 x M3 t-nuts &amp; at least 2 x<strong>Linear_Rail_alignment_helper</strong><i><strong>MGN12</strong></i><strong>+_V-Slot_2020.stl</strong> as alignment blocks. Then mount the modified Y plate to the carriage with 4 x M3x8mm screws and 4 x M3 washers.</li><li>Relocate the Y-motor mount (leave the motor attached) &amp; front idler assembly to the opposite side of the extrusion &amp; re-mount with existing screws/hardware. Keep the three screws holding the front idler on a little loose as we'll use this slack to install the belt and tension it.<i>Note: newer models will need a longer bolt as the front idler mount is different.</i></li><li>Relocate the Y-axis limit switch using<strong>ylimitspacer.stl</strong>, 2 x M4x20mm screws, 2 x M4 washers and 2 x M4 t-nuts to the opposite side of the extrusion. If you tilt the switch back while tightening it, it should fully register on the edge of the bed mounting plate.</li><li>Reuse the stock Y belt and attach it in the same insert-into-slot fashion as stock. Re-tension the belt by sliding the front idler forward &amp; tighten the three screws.</li><li>Add your favorite oil or grease to the rail (you degreased the brand new one, right?)</li><li>Do the reverse of Step 1 &amp; re-level the bed.</li><li>Move your z limit switch up a few mm's/until your nozzle doesn't crash into the bed when homing.</li><li>Print away! Video: <a href="https://youtu.be/IBlSbVZZRGk">https://youtu.be/IBlSbVZZRGk</a></li></ol><p><strong>Printer Brand:</strong></p><p>Creality</p><p><strong>Printer:</strong></p><p>Ender 3</p><p><strong>Rafts:</strong></p><p>No</p><p><strong>Supports:</strong></p><p>No</p><p>Category: 3D Printer Accessories</p>