Midwatch extruder

Use the excellent A4T improvements to the ByThorsThunder WWBMG extruder and move the stepper motor to the middle of the extruder to improve x travel and gantry clearance.

Developed to allow the latest A4T innovations (and there are lots!) to be compatible with my MadMax V0.

Shown here on hartk's glorious AntHead toolhead. Like the A4T WWBMG, this uses sherpa mini pattern mounting holes. This was inspired by the WWBMG in hartk's AntHead repository (a.k.a. "Mandible") which uses a similar motor placement.

I added a little spot at the back with space for a couple of heat set inserts, and I've provided an example accessory that can be mounted there to improve wiring to a toolboard.

The idler is stock from A4T repo and included for completeness. You can probably use their smooth idler with this too, I didn't test it.

License inherited from A4T.

Changelog:

v0.3 modified motor plate. Fixed some CAD artefacts (don't worry there are still lots, but it should be more likely to import correctly now).

v0.2 modified motor plate. Increased clearance for plastic gear. Increased depth of heat set holes. Improved printability.

v0.1 release

The stepper motor is relocated to the middle of the extruder.