Thread gauges from BAER: Guaranteed standard-compliant threads

Thread gauges for testing internal & external threads

Cutting a thread is usually not enough. Especially in industry and trade, it is indispensable to ensure that the threads also comply with applicable standards by regularly checking them using thread gauges. If the diameter is too large or the pitch too steep, it can otherwise happen that the outer and internal thread threads do not fit together perfectly. And in the worst case, this leads to unusable components or even safety risks.

To quickly and reliably check the dimensional accuracy of the threads you cut, you need testing equipment you can rely on. With thread gauges from BAER Tools you are always on the safe side. Thanks to our solid expertise from 40 years of experience in the field of tapping, we know exactly what is important. In our range you will find the right testing equipment for every application, from thread gauges in inches to thread gauges for fine threads. And if you are unsure or have any questions, our friendly team at customer service will be happy to receive your enquiry via the contact form. We will be happy to advise you in detail about your requirements and respond to your wishes.

Thread gauges: What is the difference between thread measuring or gauging?

Especially with threads, high precision is important to guarantee their full functionality and interchangeability. To ensure that this is the case, various thread standards define the nominal dimensions for each thread. To make sure that your threads follow these standards, you should carry out regular checks. You have two options for this, measuring and gauging. But what is the difference between these two processes?

When measuring, you use a suitable measuring device to determine a specific measured value. Although this is helpful, it does not tell you anything about whether your thread has dimensions that comply with the standard. With gauging, on the other hand, you determine directly whether the thread is cut according to the standard. The result of this check is not a measured value, but the correct classification of whether the thread is good or rejects. The testing device you use for this is called a thread gauge.

Check your threads easily with thread gauges

Of course, you can also determine the dimensions of threads with the help of gauges. However, these require greater care in their use and can sometimes deliver inaccurate results. Thread gauges are easy to use and produce an unambiguous result immediately. You do not even have to interpret measured values and compare them with tables. In this way, thread gauges prevent measuring or reading errors and contribute to a smooth workflow. For meaningful results, you only need to make sure that the thread is free of dirt and lubricant and is at room temperature.

In addition to being easy to use, thread gauges have another decisive advantage. They ensure legal certainty, as they themselves are standardised according to DIN ISO 1502. Because no matter how often and precisely you measure, in case of doubt the result of the gauging with a standardised thread gauge is decisive. You should therefore use this important testing equipment at least randomly in your everyday business and check measurements with other measuring instruments every now and then with the thread gauge.

Thread plug gauges: The thread gauges for the internal thread

Thread gauges for internal thread are called thread plug gauges. A distinction is made between the GO thread plug gauge and the NO-GO thread plug gauge. For easier use, both gauges for smaller threads under 40 mm are mounted on a common handle and are then combined under the designation "limit thread plug gauge".

The GO thread plug gauge is the thread gauge for testing the mating dimension. This results from the interaction of the dimensions, which must be correct so that a screw of the same thread standard can be screwed in later without any problems. The core diameter is not checked; there are special, smooth thread gauges for this. The testing procedure is simple: simply screw the mandrel of the thread gauge into the thread once completely by hand and without much effort. If this succeeds, the test is successful.

Now use the thread gauge. It is sometimes marked with a red coloured ring or labelled "NO GO"; in this way, the thread limit plug gauge can also be used to distinguish the reject side from the good side. The NO-GO thread plug gauge checks the inside flank diameter and should only be screwed in a maximum of two turns. If you can screw it in further, the prescribed maximum dimension has been exceeded. The thread is therefore a reject.

Thread ring gauges: The thread gauges for the external thread

Analogous to the thread gauges for internal thread, there are also two gauges for external threads. The thread ring gauge allows you to check the mating dimension as well as the ability to screw onto the external thread. The core roundness and the outside diameter are not checked by this thread gauge. Like the corresponding GO thread plug gauge, it should also be possible to screw the GO thread ring gauge completely onto the thread by hand without using a lot of force. If this is possible without any problems, the test is positive.

The NO-GO thread ring gauge can be distinguished from the GO thread ring gauge at first glance by a red marking. It is also screwed on with little force and must not be able to be turned more than two threads. You can check this when you unscrew the NO-GO thread ring gauge. If more than two turns are possible, the thread has not passed the test. In this case, the thread is also a reject.

BAER thread gauges always test accurately

Thread gauges must be manufactured with absolute precision to ensure accurate testing. In addition, they are exposed to heavy loads due to frequent use. A long service life therefore requires a great deal of care in production and a starting material of the highest quality. If you are looking for reliable thread gauges, you have come to the right place at BAER. In addition to the common models for metric standard threads, we also stock thread gauges for fine threads or thread gauges in inches, such as those used for American standards. On request, we will calibrate your thread gauge in accordance with the applicable guidelines for test equipment monitoring and issue you with a corresponding certificate. Convince yourself of our extensive range when you visit our online shop! Of course, you will also find all thread taps to match the thread gauges, screw tap and cutting die.