I recently changed from belt drive to screw drive in the Y-axis of my printer.  That required a larger motor, so I bought a dual shaft motor that has the shaft that sticks out the back side as well as the front.  This crank allows me to turn the shaft/screw manually to reposition the print bed to do things like level the bed, work on the undercarriage, etc.  It fits tightly (I have to pry it off with a screw driver) and lets me spin the motor with my finger very easily.I originally printed it at 50% infill and the part that grabs the motor shaft didn't last.  This version was printed solid and it is holding up well.  I used 0.2 mm layers, Coex3D green ABS, no support material needed.