Nema 8 Worm Gear Print Head Redux - for foehnsturm Modular Printhead

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The overall design remains intact, but I have completely redesigned the body from scratch.Main Distinctions from Foehnsturm's design include: (1) swapping out the hot end mount for a UBIS system (2) slightly tilting the motor mount to provide more space for cooling (3) expanding the gear box to accommodate a wider variety of worm gears (4) increasing the gear box shaft to 5 mm. The bearings remain 10 mm OD.For the motor, I recommend using a 0.8A rated Nema 8 stepper, although you can also make do with a 0.6A stepper. Running at 1/4 steps at 1553 steps/mm yields good results. At 0.6A, you might be able to avoid installing a fan on the stepper motor, but at 0.8A, something is definitely needed. I employed a crossflow fan that blows across the top of the printer.I highly recommend printing the part from PETg or a more heat-resistant material, as PLA will soften excessively from exposure to the motor and hotend.You can obtain the pressure arm file from Foehnsturm's design; however, you may need to trim off excess material if it interferes with your worm gear. https://www.youmagine.com/designs/modular-printhead-nema8-worm-gearTo change filament easily, use a pair of adjustable pliers to compress the pressure arm, rather than pulling against the motor when doing so.After printing the main body, apply a hard epoxy to fill in the rectangular divot at the top of the main body where the spring bears against. This will prevent the spring from tearing up the plastic.On the 2 mm screw that passes by the mk8 filament drive gear, you must grind off the threads on the lower half to make clearance for the mk8 gear.You should use aluminum foil or a similar material to shim up one side of the motor to adjust the contact between worm and worm gear. When done correctly, the worm should be able to rotate with very little resistance.