Let me know if you get that to work. Make two, I would like to buy one from you:-)) Sounds like an inexpensive way to do it. Why not try it (carefully at first)? I think the knurl is just for grip, not a spline because when you are adjusting you move it all around.

Someone on this board has already built a unit from a cheap , basic univeral ( plus posted pics)...can't recall how he did the "ends"...in principle, I think the splines simply offer grip and are not part of a machined-match pairing...

Wil

FYI,

According to Charlie the first run of brass couplers has been ordered. Mid December delivery to purchasers is expected.