Radius Gauge

thingiverse

Daydreaming in geometry class a lifetime ago, I conceived the "3 points define a circle" principle as a means to measure an arc's radius. Mentally designing the tool presented here, I realized its potential but had no way to bring it to life ... until 3D printing revolutionized my possibilities. Touching the tool's 3 disks to a curved surface instantly reveals the radius in centimeters or inches on the dial. This innovative device draws inspiration from the "lens clock" your optometrist uses to measure the curvature of a lens with precision. Update 2015-08-01: I would like to extend my gratitude to roki@thingiverse for their text() tip, which led me to post updated code. Additionally, I strengthened the hinge since it had broken in the past. Update 2016-05-29: To cater to a broader audience, I added an "inch" version of this device, expanding its utility and appeal.