Low mass gearExtruder
by dkennell, published
An updated version can be found at http://www.thingiverse.com/thing:251227.
This is a robust, low mass extruder for 1.75 mm filament. It can be mounted to a vertical x axis with 70 mm spacing or can be mounted to a horizontal axis using the hot end mounting bolts. It is for the MakerGear hot end with the standard mounting pattern. The shaft is really milled rather than hobbed, which gives a much better "bite". It uses steel gears from Misumi which give a 5/1 gear ratio. The aluminum mounting plate acts as a heat sink, so fan cooling is unnecessary.
This extruder/carriage is about 1/2 the weight of the original on the Aluminum Mendel, allowing for faster prints and smoother operation.
Some weight comparisons to common extruders:
gearExtruder - 311g (11 oz)
Wade extruder - 549g (19.3 oz)
MakerGear 5 /1 - 457g (16.2 oz)
Minebea PG35L w/fan - 178g (6.3oz)
This project requires some metal working tools. I used my MicroMill to cut the aluminum back plate, hot end mounting plate, and the hobbed shaft. These can be done by hand if you are very careful. Print out the alumPlate Template and use it as a drill guide. I originally used a #4-40 tap to hob the shaft, but I had much better results milling the shaft. I will post a fixture for milling the shaft soon.
I recommend setting the retraction length to .5 mm and the retraction speed to 15 mm/s in Slic3r to avoid skipping steps on filament retraction at high print speeds.