I made my own, the first cut was with welded nut into threaded rod. It cost a bit to get the collars sleeved to be exactly right...
They are plenty strong enough, no movement, I have tested the welds and belted them.
I am now getting some machined up to that size just to be sure...
Which I think is the most common practice.

I am very happy at the moment because I just got an engineer to review my work and he said the welds were all good to go...

Here is a pic I sent to Lincoln....




Gavan