Cutting tiny machine screws to length

[Chuck in E. TN]

 I am assembling a team built beam engine on which all fasteners are 2-56. I purchased 100 2-56 x 3/4”, stainless steel hex head screws for this model.
I have made a couple jigs from 1/2” mild steel hex to accomplish this on my lathe.  One jig is 1/4” and one is 1/2”. I drilled and tapped each jig for the 2-56 screws, and have cut several to the size required for various components. I am having trouble with the current process. I have to really tighten the screws in the jig or they catch on the parting tool and begin to screw themselves back out of the jig.
How do you cut longer screws to length? Do you have a better way to do this without buggering the threads?
BTW, I made a nut driver type tool from a socket head cap screw, piece of brass tubing and a home made wood handle for these screws that seems to do the job, although the brass hex nuts I have are bigger than the hex screw heads.
 Chuck

[awemawson]

Take a short length of hex bar, drill and tap axially for the thread you are shortening. Counter bore and tap one end with a thread that is large enough to accommodate the head of your bolt. Screw your bolt into the jig and screw a grub screw onto its head to lock it in place. Insert in lathe chuck and part off. Obviously you need to adjust the length to the target length of your bolt.

[DMIOM]

Hi Chuck,

Tis already here on the Madmodder oracle ! - the "lantern chuck"

Dave

[Spurry]

Run the lathe backwards. Snip off the overlength with a pair of cutters, then face-off the end with normal or chamfer tool.
Obviouslythe lantern chuck is the best way, but there's quite a bit of work to make one. 
Pete

[andyf]

One way of doing it is to drill and tap holes in plates of the appropriate thickness, insert the screws and use a fine hacksaw to lop off what sticks out the other side, flush with the plate. Unscrewing will help straighten up the threads at the end.

If you want to get really  technical, tap the holes into gauge plate and then harden it.

Andy