What screw sizes are available for building guitars?
The threads on screws come in either National Coarse, or National Fine. On 6/32 screw the 6 is the diameter and the 32 is the threads per inch. Each screw size has two thread sizes each being either National Coarse or National Fine. The chart below will give you an example of the common sizes available in the American National Thread System for machine screws and not wood screws.
