Minimal Gap 1.75mm Filament Feeder

thingiverse

I've been printing exclusively with 1.75mm filament for over a year on my Ultimaker 2 ex, and I wanted to update this print to include the modifications I currently use. The filament is pushed through the extruder by a feeder that hangs above the printer from a spring. This arrangement was chosen to reduce the length of the Bowden tube to a minimum and keep it straight. I needed a suitable way to print with TPU, and I'm quite pleased with the results in ABS, except for some stringing between areas when printing TPU 1.75 filament. What it does exceptionally well is print ABS. Guiding the filament from the spool in the normal rear position is a wheel that also hangs above the printer. The feeder could be mounted in the normal position behind the printer using a much longer Bowden tube. You'll find instructions and all the code to make the components I've used in the comments and modules of the open SCAD file. One thing not shown is an aluminum collar that I turned on my lathe to replace the spring in the extruder, which has eliminated 90% of my extruder contaminant nozzle blockage issues. This is similar to the one used on the Ultimaker 2+. Changes: * Increased the diameter of the feeder output fitting boss to make it stronger and better hold the press-lock tube fitting. * Extruder adapter now uses 4mm ID tubing as an outer adapter and a pinning procedure to retain the 2mm ID tubing in the extruder on the UM2. To facilitate the proper insertion of the straight pin retainer in the tube, there's a module in the SCAD file that will let you print a pinning jig to hold the tubing in the proper orientation for inserting the straight pin. * The feeder will fit the UM2 in the normal manner or, provided in the SCAD file, is a module that will print a hanger adapter and a filament guide wheel to facilitate hanging the feeder above the UM2. This arrangement makes the Bowden as short as practical and very straight. I've added a photo of my workstation setup for this design. Two custom drawing shapes (Inkscape) were required to make cutouts used in the SCAD file, and those are also provided so you have the complete source for your own modifications. Note: It was necessary to reduce the flow rate in the firmware to 70% when using firmware v2.6.2 ex. Print Settings: * Printer Brand: Ultimaker * Printer: Ultimaker 2 Extended * Rafts: No * Supports: Yes * Resolution: 0.4mm * Infill: 100% * Notes: Printed using ABS, Utilizes a spring I purchased from a hardware store, Suggests replacing extruder spring with aluminum tube like used in Ultimaker 2+, Works with 1.75mm TPU filament. Post-Printing: This print will reuse the stock spring from the original feeder as well as the pinch bearing. Parts Required: * Push Fitting (may need to drill out to 2mm ID) * One 40mm x 3mm machine screw and nut * One 12mm x 3mm machine screw and nut * 2mm ID TFE tubing * 4mm ID TFE tubing