Adjustable IR Sensor Chimney for Prusa i3 MK3s with MMU2s

prusaprinters

<p>This is a remix of a the great work done by ad_lamy. His Pass Through tool head and motor mount has a lot of improvements for the tool head on the original Prusa i3 MK3s with the MMU2s. Kudos. <a href="https://www.thingiverse.com/thing:3467644">https://www.thingiverse.com/thing:3467644</a></p> <p>These mods are specific to the IR Sensor mount also known as the Chimney. This mod uses a small metal spring to push against the Motor mount. All you have to do to adjust, tune or calibrate the IR sensor is tighten or loosen a single M3 screw. I have also modified the Extruder Body and Motor mounts so they have little wings that HOLD flexible filaments into place. I have tested this on both of my Prusa MK3s with MMU2s printers for a few months now. They work with TPU and Ninja flex for the most part. I can print with those materials but the MMU can't switch and load them automatically.</p> <p><strong> Two Issues</strong><br/> 2 The tall chimney can flex too much in my opinion. The pressure from the PTFE tube as it moves along the X axis can cause the chimney to flex a few microns. The best/most reliable way to solve this would be with a firmware update. Move the Carriage into the middle of the X before loading filament to the nozzle. That way the tension from the Bowden tube is always the same. This could also be helped with other materials that don't flex as much as PETG.<br/> 3 TPU and Flexible filaments are still a problem. They just flex too much so the arm doesn't move as far. Granted this design allows you fine tune for these filaments but then you need to re tune when you switch back to other filaments.</p> <p>So while I think this is a great mod I have heard that other people are getting better results from this "ZERO BEAST" mod instead.</p> <p><a href="https://www.prusaprinters.org/prints/7690-tzb-mk3smk25smmu2s-extruder-mmu2s-no-tower-v2">https://www.prusaprinters.org/prints/7690-tzb-mk3smk25smmu2s-extruder-mmu2s-no-tower-v2</a></p> <h3>Print instructions</h3><h3>Instructions</h3> <p><strong>Print Settings</strong><br/> My 3mf file already has all the recommended settings if you use PrusaSlicer. It includes Variable layer heights on a few pieces</p> <p>.2 layer height<br/> PETG. because it is strong and flexible. DO NOT use a filament that is brittle like PLA.<br/> Infill Doesn't matter<br/> Raft Doesn't matter<br/> Perimeters At least 3</p> <p><strong>Requirements</strong></p> <p>This mod REQUIRES the pass through tool head found here.<br/> <a href="https://www.thingiverse.com/thing:3467644">https://www.thingiverse.com/thing:3467644</a></p> <p>Hardware: (1) M3 x 12mm (or 14 mm) screw<br/> Spring: (1) 5mm Diameter. Less than 4mm long when compressed</p> <p><strong>More important information will follow but here are some highlights...</strong></p> <p>I found that the Idler Door would rattle on the long M3 bolt. That's not good because that means the door is moving and so is that arm that blocks the sensor. So I used a lighter to soften the plastic. Then use pliers to make the holes smaller. No more rattle meaning no more inconsistent Idler Door positions. I will eventually post a new file with a smaller hole.</p> <p>Make sure the screw in the back of the chimney is snug enough to to hold the chimney level to the top of the motor mount but loose enough to let it slide left to right. Then don't forget to tighten it back down when you are done.</p> <p><strong>If you need a spring you can get one out of a Pilot G2 pen. It will be too long. You would need to cut it in half before you could use it.</strong></p> <p>In one of the images you can see the two little wings that hold the filament in place between the bondtech gears. You can also see that over time they are worn down a little this is fine. It might make a noise for the first few hours of use but after that it is normal and a perfect fit.</p>