I needed to turn and thread an 8 pitch worm thread in steel for a dividing attachment I was building for the mini lathe spindle. The mini lathe has no back gear and so I was unable to slow the lathe down enough to eliminate the chatter. I had read about other mini lathe owners using a hand crank to keep RPM's down so I decided to build one. I found several ideas on the internet and found one I thought would work. In my junk box I had an old bicycle crank, I disassembled it and salvaged the spindle with bearings and machined the spindle down to suit keeping the plastic sleeve intact to serve as a grip for my hand. The crank arm is a piece of flat stock that has a square hole machined in one end which fits onto a square boss on main shaft to prevent turning. The main shaft locks into the lathe spindle by a taper shank and expanding and slotted mating sleeve. This arrangement grips tight. It serves my purpose well and is comfortable on the hand.