The B'Struder is an entirely new Bowden extruder design. It fits all common stepper motors, and all popular pinch gears. Variants are available for several common tube connections.
YOU PICK THE EXTRUDER HARDWARE! All you need is a few M3 screws/nuts, a suitable ~3/8" or ~10mm spring, and three 623 bearings.
Unlike most extruder designs, the B'Struder filament path runs entirely through the spring idler arm. This accomplishes two unique things:
1) Makes the filament path alignment very tolerant of different pinch gear diameters
2) Makes tension on the Bowden tube (due to filament pushing force) mildly assist pinch gear grip
This requires very specific geometry for the hinge, idler bearing, output fitting, and pinch gear contact point.
This is a new design, and feedback is welcome. But it's working great in my Delta so far. I'm running very aggressive retraction settings without any issues. Let me know how it works for you!
[UPDATE 11-13-15] Performance has been consistently awesome. I have two of them running with a lot of hours on each. The only real changes I have in the "to do" list are:
1) Widen filament inlet a bit
2) Add more fitting options (eg E3D pushfit insert, M4 tube back to the drive gear for flexibles) -- SEE REMIXES FOR MORE OPTIONS
Print the arm at 0.1mm with >50% infill and good print cooling. PLA should be fine. No supports required if printed "upright" as the STLs are oriented. May require minor cleanup of bearing pockets or filament path with a hobby knife / drill depending on your printer.
Stick an M3 nut in the nut pocket, insert a 623 bearing into the bearing slot, and screw a 12-14mm M3 screw into the nut to capture the bearing. Stick two more 623 bearings in the hinge pocket. They should be a snug fit.
Print the plate with whatever settings you want as long as it's strong. No supports required. I recommend ABS if you run your motor hot. (I'm using PLA with motor current not maxed out, but that's risky.) For NEMA 17 motors, align the hinge pivot hole with the motor bolt pattern. For smaller or geared motors, align the slots with the motor bolt pattern and break away the supports in the hinge pivot hole to expose the M3 nut pocket.
Bolt the plate to the motor. Bolt the arm hinge to the plate snug, but not so tight that the bearings bind. (A dab of thread locker is a good idea.) Install the pinch gear on the motor shaft and confirm alignment with the idler. Insert spring.
Pretty much any common extruder stepper with a centered shaft and 22mm "pilot." Should include:
Any NEMA 17, geared or ungeared
Most NEMA 14s, geared or ungeared
Compatible pinch gears:
Should work with pretty much anything from 9mm to 12mm diameter
Tested: TriDPrinting.com 8mm bore hardened pinch gear
Tested: Makerbot Mk7 gear
Tested: Random eBay mk8 gear
Tested: QU-BD Raptor
Other hardware required:
3x 623 bearings
1x M3 screw 12-14mm long (idler bearing shaft)
1x M3 screw 20-25mm long (arm hinge, length depends on motor)
2-4x M3 screw 5-8mm long (motor mount)
2x M3 nuts
4-6x M3 washers recommended
1x spring approx 3/8" or 10mm diameter, ~25-30mm long (to compress to ~15mm in use)