MK8 Spring Loaded Upgrade Designed for Stainless Steel Printing

thingiverse

To address my arms' upward movement, I searched for a permanent solution. Numerous aluminum and ABS models exist; I chose the MK8 design, incorporating Whpthomas's pin-and-tab feature and modifying it for Shapeways' stainless steel printing. Although Shapeways provides large tolerances, my received part was accurate within .15mm. Be mindful of possible tolerance issues when ordering. I had the MK8 extruder arm printed at Shapeways (http://www.shapeways.com/model/1049270/mk8-extruder-arm.html?li=productBox-search), while the back piece was printed in PLA, showing no warping. The back piece serves as a spacer, holding the spring and avoiding extra weight. Materials include 3x10x4 bearings, 10mm M3 button head bolts, nuts, washers, flat head M3 x10 bolts, and compression springs (e.g., Jones Spring: http://www.springsfast.com/part_detail_compression.php?part=C12-041-040&PHPSESSID=542e09c99ec81bbb617ba42c4462f283 or McMaster Carr part # 9657K333). The process involved printing the pin upside down, securing the back piece with a flat head bolt, tightening the hole for the bearing screw slightly, and adding a nut for extra support. A single original bolt holds the arm with the pin inside, while a little grease is applied to the pin. Finally, insert the spring and reassemble the parts, which have been printing smoothly for about 40 hours without issues.