A thread plug gauge is a very specific tool that allows you to make sure that various components fit together properly. In order for your thread plug gauge to provide you with accurate results, you need to make sure that you are using the thread plug gauge properly. Improper use could result in your thread plug gauge becoming damaged, and thus not providing you with the information you need.
#1 Be Careful with Pressure
The first thing you need to do is make sure that you are careful when applying pressure. There is no exact system for applying pressure to your thread plug gauge. However, when you apply a thread plug gauge, you should not have to apply force. It should easily fit into the threaded hole without you have to apply a lot of extra pressure.
If you have to apply a lot of extra pressure, there is more than likely an issue with the threaded hole that you are trying to use the thread plug gauge on. If you can't get the thread plug gauge in without the use of excessive pressure, don't try to force it into place.
#2 Only Have the Right Sized Gauge On Hand
Second, make sure when testing threaded holes that you only have the exact sized thread plug gauge that you need on hand. Look up the size of the threaded hole that you are working with, and get out the thread plug gauge that is that exact size.
Do not have other thread plug gauge outs. That way, you don't try to accidentally force the wrong sized thread plug gauge into a threaded hole, doing damage to the gauge and to the threaded hole at the same time. This is a simple trick to ensure that you don't make a mistake.
#3 Work Slowly
When testing multiple threaded holes, remember to work at a slow and steady pace. Do not rush when trying to get thread measurements. You are most likely to damage the thread plug gauge during the insertion and removal of the gauge into a threaded hole, especially if you are rushing and being rough.
Instead, take your time with each measurement, carefully putting the thread plug gauge into each threaded hole and gathering the accurate measurements and data before taking the thread plug gauge out. Taking your time will ensure that you get accurate measurements without damaging your tools.
The key to taking care of your thread plug gauge is to use it with care. Be careful and precise with how you use the tool in order to ensure that it lasts.