Using the wrong bolt in a threaded hole will instantly strip the threads, leading to costly repairs. A thread pitch gauge helps you identify the exact thread sizing. It features a pocket-knife style set of thin metal blades. Each blade has a series of teeth cut along its edge that match standard metric or SAE thread profiles, labeled with the pitch value (like 1.25mm or 16 threads per inch).
To use it, you press different blades against the threads of the bolt until you find one that locks into the grooves perfectly with no gaps. Once matched, read the number stamped on the blade. Metric pitches measure the distance between threads in millimeters, while SAE pitches count the number of threads per inch. Keep the blades clean of grease to ensure a precise fit.