Mini Lathe Hand Crank

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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.

Beyond threading, a hand crank is useful for non-violently unscrewing chucks, etc. from threaded spindles. Stop the chuck rotation with a piece of wood and use the crank to gently unscrew the spindle from the chuck.

Even better though is to remember to oil the spindle threads before screwing anything on to them. I have an oily toothbrush for this purpose. With the naked spindle running slowly in reverse apply the brush to the left side of the threads and allow the threads to move the brush to the right to the end of the spindle. Swarf is swept off and an oily surface is left behind to eliminate the need to use the hand crank.

mklotz,
Thanks for the advice Marv on threaded lathe spindles. I have had times long ago when I wished I had lightly oiled the spindle threads. It can be a big issue when a chuck was spun on too fast and the threads lock up tight. In my case though, my mini lathe does not have a threaded spindle so I don’t have to worry about that.

Quote:

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Originally Posted by old_toolmaker

mklotz,
Thanks for the advice Marv on threaded lathe spindles. I have had times long ago when I wished I had lightly oiled the spindle threads. It can be a big issue when a chuck was spun on too fast and the threads lock up tight. In my case though, my mini lathe does not have a threaded spindle so I don’t have to worry about that.

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I like to offer tidbits of advice like this even if they don't apply to the OP's situation. Future readers of this thread may learn something that helps in their unique situation.

Hi Marv,
You make a good point and I agree. Thanks for pointing that out.

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DYIer,
Thank you!

one way bearing on that and it's kinda oops proof....just incase you hit the on switch... it could also have a thumb screw to lock it to the shaft for reversing or rocking back and forth. just dont forget it's locked...a soft pin/screw may be good idea there.

Marksbug,
Thank you for making a good point. A one way bearing would be great but in my case the spindle can be easily reversed so that would not solve all potential accidents.
I disconnect power to the lathe before installing the hand crank. That is my method my fool-proofing.

one for each direction and a "soft" detent drive pin to lock it to either direction..... I like a hand wheel idea better than a handle for me...sometimes my hands are faster than my brain... I guess kinda like some of the draw bars have.Ive seen a big one behind the chuck on somebodys setup. I do like the looks of yours, and a one way bearing means you can crank it like a ratchet and not have to go all the way around with handle.. last year I was looking at the one way bearings so I could put one on my 4 wheeler on the rear solid axle so I didnt tear up the lawn hauling my yard trailer...but never got past the thinking stage.

Marksbug,
Your ratcheting idea is interesting, but
for my application I much prefer to use a smooth and steady approach to my turning using a hand crank. I am not interested in a ratcheting arrangement as it provides a start and stop action and that would not be a smooth and steady action.
I’m not saying here that a ratchet is a bad idea, but it is not for my application.

yes I under stand that.totaly. thus the ability to lock it if needed. a nice steady hand is nice to have many times. and yours would be easyer than turning a hand wheel unless it has a handle.