I got this rod to rod jig idea off another site and thought it was pretty good. My jig is made of 1 aluminum angle (because that is what I had), the window is 2 long and the total length is 4 long. I had a couple of short SS 3/8 rods lying around and did not want to cut a larger piece down. I beveled the ends to be welded on the lathe, clamped them in the jig, welded them together and finished the rod off on the lathe.
Pic 1 &2 Two pieces beveled and clamped in the jig (top and bottom view).
Pic 3 Welded pieces after wire brushing.
Pic 4 Finished rod, just a couple of pits I didnt fill in.
It was a very easy to align the rods and the final produce spun pretty true in the lathe.