Spherometer - $225

Measures radius of curvature of convex and concave surfaces. Aluminum base (3/8") with heavy stainless steel feet and fittings. Dial micrometer graduated to 0.001 inch. Accuracy varies with radius being measured, but is around 0.2 inch for radius of 50 inches; less for shorter radii. This four inch footprint size is good for glass blanks 5 inches diameter and up. New, with instructions. A real help with concave and almost a necessity for convex surfaces. $225 plus shipping.