Remake of bdring's extruder mod. Thank you bdring!
This extruder block and lever is used with an mk7 style drive gear and McMaster-Carr pn 6138k64 bearing with 3/16 inch ID and 1/2 inch OD. This extruder mod does not require sourcing any screws, which is its main benefit. Simply push the bearing onto the printed shaft for a snug fit. The design is mounted with the mk7 style drive gear set screw positioned away from the stepper motor so that the set screw rests on the stepper spindle flat to prevent slipping. This method also reduces the lever arm with respect to the stepper's internal bearing and the filament contact position. I adjusted the spring cavity for a spring that I was previously using. I found it easier to rework the cad file than to look for a new spring.
Thank you open source reprap community!