I'm really sorry to make another post, but it appears I missed some specs when first glancing over those links.
http://www.ruland.com/ps_couplings_rigid_clx.asp
In that link they list a model that has a 1/2" side and a 3/8" side.
I maybe be able to make that work.
I also noticed on this...
I am not sure how to edit a post, so unfortunately I have to make another.
These seem like they could be suitable:
http://www.ruland.com/ps_couplings_rigid_mscx.asp
http://www.ruland.com/ps_couplings_rigid_clx.asp
If they were available with two different internal diameters.
It is a lever. The force will be applied approx. 5" away from this joint (with the center of rotation approx. 2" in the other direction). It will be a few pounds of force, so it will have to be fairly sturdy.
I think more surface contact will be necessary than that of the collar-type...
I'd like to couple a 14mm solid steel shaft, to a 10mm x 1.5pitch
threaded rod. If possibly I'd like to avoid modifying the
shafts in any way (threading the smooth one, drilling holes,
ect). Also, I would like the coupler to be removable.
For the smooth shaft I was thinking of either...