Breech Block Suite for Zesty Nimble

thingiverse

First and foremost, I find that standard Breech Blocks work very well even for Makeshaper Ultra-Flexible TPU (nee X60) filament. I use these modified blocks for one specific application. Note well that extra compression of soft filaments can easily result in the filament being squeezed between the drive wheel and the lower filament guide lip. If unnoticed, this situation can cause enough filament to be driven into the Nimble to the point that the halves become separated and the worm gear is damaged. Caveat Emptor. Minimize extrusion resistance and speed. Performing a test of desired settings by extruding 10-20mm then opening the breech to inspect is recommended. The X in the pX file designation indicates the amount of additional filament compression in tenths of mm. The zip file contains 123D Design files, step files, and images. Required Components: * 3 pieces of 3mm shaft or 3mm shanked/partially threaded SHCS - minimum 12mm grip length. * 683ZZ ABEC-7 10PCS 3x7x3 mm Bearings Tools: * 3mm Reamer (ideally) or 3mm drill bit to size cross holes. * Small rounded edge riffler file to clean up filament guide groove. Printing: * Material: Stiffer material that allows for reasonably clean support separation and is amenable to machining operations i.e. PETG. * Layer height: 0.125mm. * Extrusion width: 0.3mm or so. * Support: Required - I used an x, y gap of 0.25mm and z gap of 0.125 with PETG and my lamentable single filament setup. * Orientation: For best cross hole location accuracy, print on side (as shown in stl renderings above). Instructions: * Prepare cross pins - see photo. 7mm for the bearing pin, minimum 12mm grip length for the upper and lower pins. * Remove support material with care, ensure bearing is firmly gripped by the inner axle ring but is able to turn freely when installed. * Carefully ream 3mm holes - oversize holes will defeat the purpose of the exercise. * Clean up filament guide path groove * Ensure Breech Block fits correctly without interference. (Note: Clearances are tight so a little fettling, particularly on the bottom of the breach block, is likely required.)