Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:4470029.
Experimental Nut Cracker. Awaiting testing. Pictured with aluminium reinforced jaws, though on its own has a hard bite. Gear ratio 1:41.667.
Prints in place fully assembled without supports.
IMPORTANT: Print at 0.2mm layer height if using the default model, otherwise ensure layer_h parameter matches your layer height if customizing. Check preview before printing and ensure the 1-layer gap is preserved in the outer ring gears.
Use a sharpened spatula, razor or hobby knife to de-laminate the 1-layer gaps (watch fingers and listen for the "crack"), then turn the knob just a little to get the gears moving. Now "crack" the jaws apart manually by back-driving by a few mm (there should be a little backlash). Now all the parts are free, it will be a bit stiff at first but opening and closing a few times will loosen it up. Then apply petroleum jelly or lubricant of choice to gears and work it in (again by opening and closing a few times). Optionally reinforce jaws with aluminium angle or stainless steel and a bit of glue.