I'd already leveled her in plane.
Before I began the two collar test I thought I'd do a tailstock coarse adjust with a mandrel and a .0005 dial indicator.
I had a bucket of large mandrels that I've been pushing around the shop for a year (got'em at scrap value).
I'd sorted out the little ones already for a machine job this past summer.
Remaining were .75-2inch.
I found a really long one and rolled it on the surface plate to check cylindricity (qualitative).
Checked out nicely.
At this point I noticed that this ~1.25inch mandrel was about 18inch long.
Really long for a mandrel, or at least the ones I've used.
On closer inspection it was stamped "Test Bar" on the end.
Yes, I need to find better storage for all of them....
Does anyone know if test bars (and mandrels) have "airy" points like straight edges?
Or, should the entire bar be supported?
I've hung my camel-back straight edges and horizontal arbors vertically.