Making a bronze thumbscrew

[spike7638]

Spike, not sure what kind of lathe you have but do yourself a favor and buy or make a scissors knurler. When you say "side-load", it implies you're planning to use a bump knurler that indeed puts a lot of load on the spindle, spindle bearings and the part. A scissors knurler will eliminate that.

I would make the part just like David S said. On a part this short given the OD of your stock, you do not need a live center unless you use that bump knurler.

Parting can be a problem on smaller lathes. One good option is the FoR Parting Tool from Eccentric Engineering if your lathe can run in reverse and doesn't have a threaded spindle. If your cross slide has T-slots then a rear mounted parting tool post would be ideal and will eliminate your parting issues/fears completely.

"Scissors knurler" -- a new term to me, but I think I can see what it might look like. I'll ask the folks at the shop of there's one I can use (it's a machine shop at our University, not my own, alas.)

 

[Cooter Brown]

Turn the thread OD and then the shoulder OD... Cut the threads, Knurl, chamfer the all the corners and then part it off....

 

[jdedmon91]

If you want a one piece thumbscrew I’d turn the material to the OD of the thumbscrew then knurl it, in fact do the OD and knurl long enough to make several screws. Then turn the first screw down to thread size, and thread it. The part off and do it again.

However I never make one piece thumbscrews I do the same OD operations then drill and tap for either threaded rod or a screw of the appropriate size and length. You can buy brass screws. Loctite then together I use 620 bearing mount the face the outside flat. I use a fixture in the 3 jaw to screw the thumbscrew in


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[spike7638]

If you want a one piece thumbscrew I’d turn the material to the OD of the thumbscrew then knurl it, in fact do the OD and knurl long enough to make several screws. Then turn the first screw down to thread size, and thread it. The part off and do it again.

However I never make one piece thumbscrews I do the same OD operations then drill and tap for either threaded rod or a screw of the appropriate size and length. You can buy brass screws. Loctite then together I use 620 bearing mount the face the outside flat. I use a fixture in the 3 jaw to screw the thumbscrew in


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D'oh! I should have thought of using threads that someone else already cut for me! This simplifies things a good deal. I think I even have some spare 1/4-20 bronze screws lying around.