Stigma (letter) Stigma (letter) Stigma (ϛ) is a ligature of the Greek letters sigma (Σ) and tau (Τ), which was used in writing Greek between the Middle Ages and the 19th century. It is also used as a numeral symbol for the number 6. In this unrelated function, it is a continuation of the old letter digamma (originally Ϝ, cursive form ), which had served as a numeral since antiquity and was conflated with the σ-τ ligature in the minuscule handwriting of the Middle Ages. The στ ligature (, ) was one of many ligature forms that came into widespread use as
Torque tester Torque tester A torque tester is used as a quality control device to test or calibrate torque controlled tools. This includes electronic torque wrenches, click torque wrenches, dial torque wrenches, electric screwdrivers, air screwdrivers, pulse tools, cordless screwdrivers, nutrunners, and torque screwdrivers. Today’s advanced torque testers include the ability to measure in clockwise and counter-clockwise directions, convert to 8 engineering units (in·oz, in·lb, ft·lb, N·m, cN·m, kgf·cm, gf·cm, kgf·fm), 3 modes of operation (peak, 1st peak, track), and include a National Institute of Standards and Technology (NIST) certificate (or its domestic pendant). A torque transducer, similar to a load cell,