Spring Calipers & Dividers

A spring joint caliper uses a curved spring steel arch at the pivot, tensioned against a screw, allowing precise one-handed adjustment and a setting that stays put under normal handling. A firm joint caliper relies purely on pivot friction, adjusted by tapping the legs against a surface — simpler and often cheaper, but less precise to fine-tune and more prone to slipping out of setting.

Outside and inside calipers have curved legs ending in rounded contact surfaces designed to measure or transfer external or internal dimensions on a workpiece. Dividers have two straight legs ending in sharp points, designed to scribe arcs and circles, step off equal distances, or transfer a measurement point-to-point from a rule — they're not meant to contact and measure a curved surface the way calipers do.

Set the calipers to a known dimension (from a rule or gauge), then adjust the legs to just touch the workpiece surface without forcing them — the 'feel' of a light drag is the traditional technique for accurate transfer. The caliper itself doesn't display a number; you either compare it against a rule or use it purely to check that a dimension matches a reference.

A hermaphrodite caliper has one curved (caliper-style) leg and one straight, pointed (divider-style) leg, used for scribing a line at a set distance from an edge — the curved leg rides along the workpiece edge while the pointed leg scribes the layout line. It's a specialized layout tool distinct from standard inside/outside calipers or dividers.

Spring calipers and dividers remain useful for transferring measurements to irregular or curved surfaces a digital caliper's jaws can't reach, for scribing layout lines directly (which a digital caliper doesn't do), and in shops that value tools with no battery or electronics to fail. They complement rather than replace digital measuring instruments for many layout tasks.