For Sale: 8 inch precision spherometer with three (3) point ball feet and a dial
indicator. The span is extreme high precision machined 4.0000" to the center
bore, and the ball feet are precision 0.375" in diameter. The indicator locking
collar is improvised from a welded nut and nylon bushing, but it works very well.
Spherometers are used by professional opticians and advanced telescope mirror
makers for monitoring the depth of the curve, or "sagitta", during coarse and fine
grinding glass operations.
Included is a dial indicator with 0.001" precision, 1" travel and a rounded probe
tip. Also, an excel spreadsheet for calculating your Radius of Curvature from
the precise sagitta measurements which can be taken with this instrument.