When you are out on a job site, you are going to have to deal with all kinds of equipment and material. You may not always know all the ins and outs about about every single piece of equipment. That can include what kind of thread pitch you are working with when it comes to anything that has been threaded. When working with threaded objects, it can be very difficult to find exactly what you need, especially when you're trying to find just one individual screw, bolt, or piece of pipe in the midst of a bunch of other types. But there are gadgets you can use to help you determine which one to use. One of those gadgets is a thread gage. Before discussing thread gages, though, there are two points you need to know:

Screw Lead and Pitch

The screw lead and the screw pitch are very similar and in many cases are the same thing. They are both distance measurements. The lead refers to the distance that the screw travels in one full 360 degree rotation. The pitch measures the distance between the crest of one thread and the next one. In a single threaded screw, the lead and the pitch are generally the same distance. However, in a screw that is double threaded, they are not going to be the same distance. 


Threaded objects come in two genders, male and female. A threaded object that is female is threaded on its interior. A threaded object that is male is threaded on the outside. A screw would be a male object and the corresponding nut would be a female. 

Now that you understand screw lead and pitch and genders, read on to learn about thread gages themselves.

Thread Gages and Plugs

When you need to know the pitch of a threaded object, a thread gage or plug is the correct tool to use. The gages come in a set on that is generally on a ring, similar to a set of keys on a ring. Each leaf of the thread gage set has a slightly different pitch ratio. In order to use the set correctly, you just need to put the leaf up against the screw. If it doesn't fit correctly, then you will need to go up or down in size until you get the right one. A thread plug will be slightly different. You are going to have to try to screw it into the pipe, nut, or other object to see if it fits. If it doesn't, then you will need to try a different plug.