MIMF

John, that's an interesting refinement. I've seen 3/16" square rods used and they also solve the torque problem at modest weight increase. Rounding the stock requires a lathe and 4 jaw or square collet.

Chuck Tweedy wrote: John, you should be able to anneal / temper the welded assembly back to a non-brittle state. Maybe you have tried with with the drill rod and it didn't work - that may be, but I'm sure it would work if you used O1 oil-hardening steel rod.

I'm sure there are drill rods and annealing processes that would work fine, but the welding rod works fine with no annealing, and I had to get a whole package from the welding supply rather than just a few rods, so I have far more than a lifetime supply!

Hard to argue with that!

I like the idea of the flat.

Hmmm...., how about using some flat bar and just welding the threaded section of a bolt at the end?