HeliCoil Gauges are available as Go/No Go thread plug gauges for inspection of tapped holes prior to HeliCoil fitment. The gauges are available in 5H & 6H class for Metric sizes and 2B/3B for UNC/UNF sizes.
Accuracy of the finished thread when the insert is installed is dependent upon the accuracy of the tapped hole. If the finished tapped hole gages satisfactorily, the installed insert will be within the thread tolerance. It is not necessary to gage the installed insert. After the insert is installed, the GO thread plug gage may not enter freely; however, the insert will always seat itself when the bolt or screw is installed and tightened. (Reference NASM33537).