On Nov 11, 4:56*pm, David Billington
wrote:
...

Maybe a bit large for a mini mill but the rod used on car damper struts
could be of use and readily available. Last dampers that came out of my
VW I kept and were 22mm OD chromed ground bar and while I could see the
wear area by the finish the difference in size from the unworn sections
was almost indistinguishable with a 0.01mm graduated non digital
micrometer, maybe in the order of 0.001 mm to 0.002mm.

IIRC Rollie's Dad used a shock absorber rod.

jsw