There are fortunately a lot of gage options available when inspecting screws and nuts. However, you will need to make sure that you select the gage that is right for what you are measuring. You will also need to know how to properly use your gage.

Using Gages

Gages are important in situations where each of the nuts of a machine must bear a specific load. If a nut fails to bear this load, you are more likely to see the machine fail. Unfortunately, there are cases when you do not know the specifications of a nut or bolt and you will need to test it with a thread plug gage.

Choosing The Right Gage

One of the most common types of thread plug gages is the fixed limit thread gage. They are known for being simple, cost-effective and reliable. Therefore, they are used throughout the assembly of a product for quality testing.

Another option is the working and master gages. These devices can verify the correct pitch and size diameter for external and internal threads. Given their high accuracy, they are used under situations where a thread must be accurate down to millionths of an inch.

Making Sure The Gage Has The Right Size

Make sure to select the correct-sized plug gauge for the externally threaded product. This is easier when the drawing and specification requirements are available and are accurate. To make sure that the thread gage is compatible with the product, you must know the:

  • TPI/pitch
  • Major diameter
  • Class of fit

Also, the gage must conform to the ANSI/ASME B1.16M. While most gages in the United States will, you may run into an incompatible gage when working with international customers.

Once you have the right gage, using the gage is easy. The NoGo thread plug is shorter than the Go. When the Go thread plug goes inside the threaded hole and the NoGo does not, the product is within the tolerance limits. Never force the NoGo to enter the product thread.

Checking All Elements Of The External Thread

When using a thread ring gage, make sure to use a setting plug or a master plug. These plugs check the calibration of the thread ring gage so that it can check all elements of the external thread, excluding the major diameter. Check the major diameter with the master plug or setting plug. Master and setting plugs are important because they are designed with closer tolerances.

Contact a company, like WEST port, for more help.