Fig 1Four-stop height comparatorMove the carriage · arrows step between blocksblock 1 · reads 2.40 mm
Plunger and needle: what moves when the height changesFour gauge blocks: 2.4, 1.8, 1.2 and 0.6 mmA dial indicator on a surface plate. Slide the carriage and the plunger rides up or down onto the block beneath it; one turn of the needle is 2 mm of illustrative travel (10 drawing units per mm), so every block reads its own height.