When it comes to pipes and screws, or anything that has threaded section to it, it's important to make sure that threads are measured correctly and that the measurement is labeled so that when people go to buy the pipe or screw, they know what they are getting and they are able to get the right thing. That takes a thread gauge. This tool is used to measure the thread, but how are the threads measured?
Threads Per Inch
One measurement for threads is the threads per inch, or TPI. This is a pretty simple measurement. You just take an inch of the screw and count how many threads are in that inch. This works best on screws and pipes that aren't metric. Metric screws use a different count. They are measured by the thread pitch, which is one of the things that a thread gauge will measure.
The thread pitch is measured by looking at the space between the crest of one thread to the next. It doesn't matter if the thread is a single tap or a double tap screw, the way to measure the thread pitch is still going to be the same, from the crest to the crest.
A lot of people confuse the lead and the pitch because the way that they are measured can look very similar. The lead of the screw is also measured using a thread. The difference is that the lead is measured by counting the distance that the screw or pipe would travel along its axis from one point to the parallel point on the threads. In a single tap screw, the lead and the pitch should be generally the same.
Starts are super easy to measure. The start of a pipe or screw thread is just that, the place where it starts. A single tap screw has only one start, where a double tap screw has two starts, one for each thread ridge. Adding the additional thread of a double tap screw will slightly change the way that the pitch and lead are measured. When measuring the lead, it will be measured between the threads of the same thread ridge, ignoring the second thread ridge altogether. The lead, however, will use both thread ridges as part of their measurements. It will still measure from one point to the next along the travel of the screw.
Measuring pipe and screw threads is important. A thread gauge is used to take several measurements in order to correctly size the thread. For more information, reach out to companies like WESTport.