Radius Measurement tool

Need to measure the radius of something to CAD a holder or accessory?
Need a way to model and reproduce that sleek round surface?
This might help.

Attach to a Digital Dial indicator in order to calculate the radius of a curved surface.

Designed to fit a Digital Dial Indicator with a shaft diameter of 8mm, such as
"Neoteck DTI Digital Dial Indicator 1''/25.4mm | Digital Probe Indicator Dial Test Gauge High Resolution: 0.0005''/0.01mm" on Amazon US.

How to zero:
raise/lower the plastic component along the shaft while placed on a flat surface... It should be just touching the surface at probe's full extension. Can be optionally secured using a #6 set/machine screw. There is an optional second channel parallel to the main one, in which a #6 set screw can be inserted in order to assist in holding the part off the dial indicator at a certain distance in order to help zero with more precision.

Formula for determine radius:
Radius=[(Cord Length^2) /4+ (Measured height^2)] / (