Just a small update showing how the connection for the back stay is made.
I machine a slug from bar stock that is pressed into the end of the tube. The socket piece is also machined inside to make it concentric and smooth. The slug is a neat slip fit. I also drilled out the center of the slug to reduce a bit of weight.
With the whole thing clamped down in a section of angle iron I can make sure it's all in line ready for welding. The slug and the end of the pipe are machined/ground to give a nice V groove for the weld.
This back stay is in mild steel so not as shiney but much easier to work with than stainless.
Tig weld the slug in place. TIG gives good penitration without adding a lot of extra filler material. The weld needs to be good since It'll be linished smooth on the outside.
After linishing the weld back slip the socket section on and clamp it in the mill vice. Drill, tap and countersink for a 10mm retaining screw on both sides.
To make the retaining screws a bit nicer looking I put a countersunk head cap screw in the lathe and machine the shoulders of it off to more of a dome shape.
Set screws in place. The countersunk heads keep the joint snugged closed.
Cheers