Added one to my 7x14 mini lathe.
G3190 frommatching handle H320* and 20 mins of turning/drilling will get you a no-sweat setup for threading.
Here're the basics (having a mill is a bid help - I used my mini mill):
- drill the handle's hole to may be 3/4" (can use end mills),
- cross-drill and tap 1/4-20, down the middle. Use a HHD, it is safe, watch that bubble to get a square cut.
- I used alum: get a 4" long 1 OD round. Drill through with 5/16. Enlarge the hole to 1/2 from one end to about 3/4" deep. Turn that end to .807 (my spindle's bore, measure yours), for 1.5" or so.
- turn the opposite end to the size of the hole in the wheel - .750 in my case, as long as the handle's hole is deep
- slit the .807 end - I used slitting saw and did cross-pattern cut, .750 deep. Hacksaw won't look nearly as pretty but will do the job
- get a 4.5" long piece of alum or mild steell in .600 OD or thereabout. We are about to make a rod, tapered on on end ( from .600 to just under 5/16 in 1/4 or so), turned down to .240 and threaded 1/4-20 for .500 on the other end, just under 5/16 the rest of the way
- no dims are critical - play by ear. The idea is to make it of size where the locking rod is snug, with the tapered portion resting against the slitted end and the threaded portion sticking out 1/2" with a nut on it and still have enough thread inside, so that when the nut is turned 1/2 turn, it forces the tapered end to go inside of the slit(ted?) end and enlarge the OD as the result to where it will lock inside of the spindle
- assemble by putting the big peice into the handle, lock in with a1/4 set screw or SHCS. Put the tapered rod in, screw the nut on the threaded end. Stick the thing into the spindle, turn the nut 1/2 turn - it will lock the whole assembly with the spindle. To remove - half a turn the other way and it will come out just fine. 3 seconds to install or remove, not bad.
Be safe - have the power cord unplugged_ when you use the wheel to thread. YOu will have tons of torque due to 8" OD wheel and full control so you'll never ever run into shoulder. For ultimate in accuracy when threading and to fool proof it 100%, do NOT disengage the halfnuts after you engage them, till the job is done. You simply don't have to , as now there's no fear of running into the shoulder, chuck or whatever. You will always track the thread this way ...
The heavy handwheel will also give you some inertia - for the longer threads it will come in handy.