Eccentric spacer for Raise3D N2 extruder

thingiverse

UPDATE 03/02/16: I have replaced the original with a new version that can be dynamically tensioned using a spring to adjust pinch pressure. This updated version requires replacing the original M3 12mm screw with an M3 18mm one. The acrylic cover thumbscrew has been swapped out for a longer cap screw and a printed grooved spacer, also included here, is used to hold the spring in place. This new eccentric spacer features a thinner shoulder that sits on the bearing inner ring and a bevel coming up from the bearing to help keep the filament from slipping off the flat bearing. This eccentric spacer aims to address a common issue with filament slippage caused by the fixed distance pinch mechanism on the Raise3D N2 printer. To install it, you'll need to swap out the original v-groove idler bearing for a 5mm x 10mm x 4mm flat bearing and drill out the cavity over the bearing in the acrylic front plate. Once installed, the pinch distance can be adjusted by loosening the screw, turning the spacer wing, and then holding the wing while retightening the screw. I plan to create a scale that attaches to the acrylic plate to make it easier to keep track of known good pinch settings for different filaments. I will also experiment with a version featuring two wings for improved grip while tightening, and upload that design here. Print Settings: Printer: Rafts: Yes Supports: Yes Resolution: .1mm layer Infill: 50% Notes: I printed this in PLA, but I plan to print one out of a stronger, higher temperature plastic - either nylon or PC. I printed it with the top down, but it would be worth trying it on its side with even smaller layer height. Also, if you can print with a narrower nozzle, that would probably be a good idea. Post-Printing I used this bearing: http://www.amazon.com/gp/product/B00ART39CU I drilled out the cavity in the acrylic plate using a standard 1/2" drill bit. I drilled out the spacers after printing with a 3mm drill bit. How I Designed This This design was inspired by a post on the Raise3D community forum, where Ben Roj described replacing the v-groove bearing with a flat bearing. I suggested the possibility of an eccentric spacer and then designed one to be machined, and I printed a test version of that one, along with machining a test version out of brass. As my design evolved, You Choi Cheung suggested making it thumb-adjustable, which led me to come up with the winged version.