Coasty my mate who teaches me lathe work was back at shed today, I got 400 mm long post getting made will be hollow and i can put a mark 100 up it for min insertion, will test fit in a frame to make sure it will go in. Actually 2 being made, one for me and one to sell/ be conned out of by a Queenslander

Bought new bar for the job so it should look pretty until its been shoved in and out of a frame 20 times. If you put a smear of bronze grease on it it should still tighten up nice at clamp but not chemicaly weld itself into frame I'm told.