Bondtech - Improved extruder lid with support for dual bowden fittings

thingiverse

I'm assembling a custom BMG extruder using parts sourced from trianglelab on aliexpress. I need bowden fittings on both ends so that I can chain a filament cleaner and a runout sensor before the extruder, as well as attach a heated drybox with bowden fitting to print nylon filament without exposing it to moisture. In addition to adding the second pneumatic fitting recess, I included an arrow on the back to indicate the direction of installation. Although the BMG design might not require this clarification, many extruder designs place the idler a few degrees forward of the hob. I damaged my first prototype while trying to tap the recess with an M6 screw, so I created an additional version with the ID of that recess increased by 0.2 millimeters for easier tapping. Heating up an M6 screw and driving it in hot might be the most efficient way to tap these, which I haven't tried yet. The model also includes a spacer that fits inside the recess for the screw heads. Since I'm using a metal bracket to mount my stepper to the printer, I discovered that 35mm screws don't have enough length into the stepper body but 40mm screws are too long. Depending on your bracket and stepper, you may need to adjust the spacer's thickness by scaling it on the Z axis in your slicer. 11/16/18: I uploaded a version with M6x1 threads already incorporated into the model. Although the print quality will likely be subpar, you'll still want to prep the printed lid before driving in your bowden fittings. I've had moderate success heating up an M6 socket head screw and driving it in with a hex bit in a screwdriver to create the threads in this version.