The penny dropped in regards the quill dogs, I removed one and mounted the boring head no problem.
Photos show the set-up on the mill, and the finished product.
Size is 28.3 mm diameter, and deliberately offset a little to maintain thickness on the slotted side.
It was interesting to see the amount of spring in the bar, did two spring cuts and finished with a nice finish.
80 RPM, 10 mm/min under CNC, 0.1 mm cut.
Now to making a sleeve.
I think I will glue the sleeve in the bore, then slit it - seems the safest option.
Attachment 385849Attachment 385850
John