Prusa Bear-BMG fusion (indirect filament sensor) for MK3 / MK2.5

cults3d

This Fusion BMG extruder is a blend of an excellent extruder made by Pekcitron (Bear Extruder) and the Bondtech BMG 3:1. I tried to integrate the indirect filament sensor with a magnet, based on this design: https://www.thingiverse.com/thing:3241561 , created by RaavHimself, who is very smart. To use the indirect filament sensor, you need a MR105z bearing (5x10x4) and a round neodymium 8x3. No firmware changes are needed! You will also need one thread insert to fix the extruder bottom to the X-carriage on the left upper side. Many thanks go out to all people who tried to develop a better extruder, especially Pekcitron, RaavHimself, and Lee0101. I also want to thank Eric Clinedinst for helping me find the first issue. Here is the BOM list for the internal part: 1x 5x10x4 (MR105z) Bearing for indirect filament sensor 1x Round neodymium 8x3 https://www.amazon.it/dp/B075FKTCZG/ref=cm_sw_r_cp_apip_pkFCQPIVjH3OA 2x 5X8X2.5 Bearing https://www.bondtech.se/en/product/ballbearing-5x8x2-5 1x Shaft Assembly https://www.bondtech.se/en/product/shaft-assembly 1x Motor Gear https://www.bondtech.se/en/product/motor-gear/ 1x 3X32 mm Shaft https://www.bondtech.se/en/product/shafts/ 1x Thread insert https://www.bondtech.se/en/product/thread-inserts/ 1x Thumbscrew Assembly https://www.bondtech.se/en/product-category/spare-parts/thumbscrew-assembly/ 1x Push-Fit Connector (or you can model in Fusion to adapt PC4-....) https://www.bondtech.se/en/product/push-fit-connector/ 1x 1.75 / 5.0 Bondtech Drivergear kit. (No need if you own a MK3) 1x Pancake motor with at least 16N.cm https://zaribo.com/stepper-motors/126-zaribo-pancake-motor-by-bb-2/ 3x M3x50 1x M3x30 You can find the updates below: **** 11/12/18 UPDATE 7: New way to keep the bearing with stable pressure on filament, update bearing slide holder and extruder bottom. **** 13/12/18 UPDATE 8: New Alpha 6 design. as suggested i add a hole for square nut to fix the lever instead the thread insert and add a hex nut fo fix the fan support (instead the thread insert). i also add a square nut to keep better in place the screw for the bearing pressure. **** 26/12/18 UPDATE 9: Nothing changed here but now it out of Alpha. It is stable, i have 2 extruders mounted and they work extremely well from 2 weeks. **** 31/12/18 UPDATE 10: Added stl file of MK2.5 X-carriage. Re-upload step files for MK3 **** 03/01/19 UPDATE 11: Added stl file of Extruder top without the "Venturi hole" **** 05/01/19 UPDATE 12: Added a .pdf file of quick assembly photos **** 10/01/19 UPDATE 13: Added .stl files of cable guide back part a. and part b. Thanks to Gabe Condrea for your precious and continually suggestions and for tipped me!!! **** 16/01/19 UPDATE 14: Updated the assembly guide (thanks to repvik) **** 21/01/19 UPDATE 15: i added a version of Extruder bottom with a PC4-M6 and a Lever with a 2mm recession to solve the issue with short screw if you are using the original Thumbscrew Assembly.