Alternate Method for Measuring Grindstone

[BobD]

Figured I would post this in the off chance it hasn't already been covered and someone finds themselves in a situation without access to calipers.

With a decent flexible metal, polyvinyl, cloth etc... tape you can measure the circumstance of the grindstone. This will reduce any error or discrepancy  by more than a third (π to be exact) when converting to diameter, opposed to quickly measuring the radius where it would be doubled.

*See example figures in the pictures below

The metallic tape is a Starrett Stix. It's 4' with both metric and Imp. I think it was $4

The two others are just run of the mill tapes that are spring wound like a regular tape measure.

[John_B]

This is a great reminder of the diameter/ circumference relationship.

[Ken S]

I second John's thought.

Ken