I wanted more control while threading than just tripping the half nut on my mini lathe.
Needing to thread up to a shoulder without leaving the clearance necessary for safety.
I have seen a couple of these that were made up in different ways and I settled on the "wedge" type.
Grizzly had a nice 7" aluminum wheel that seemed about the right size...(turned out a bit large but it works fine)
The hot rolled steel arbor was turned on the lathe to mate up with the Grizzly wheel, my spindle spider, and the internal diameter of my spindle.
So there are 3 diameters involved. After turning to diameter and drilling the arbor I threaded the end that would become the wedge. The remainder of the arbor was drilled for clearance of a 5/16 piece of all thread.
The arbor was then cutoff at a 45 deg angle using a slitting saw in the mill.
The cut end of the arbor was now drilled thru so the arbor has the 5/16 clearance the entire length.
Put a flat on the end of the arbor that would hold the wheel and that was all there was to it.
The length was set so the assembly would fit on the lathe with the spider installed or if the case was removed it will fit the spindle without
bottoming out on the ridge inside the spindle where the MT3 taper was cut.
Works fine. Now I can manually thread....