Helical Coil Thread Plug Gages (STI)

Helical Coil Thread Plug Gages (STI)

During thread building / re-building operation the tapped hole plays a major role and the accuracy of finished thread after the insert is installed completely depends on the accuracy of the tapped hole. Therefore determining its accuracy is very important. If the finished tapped hole is accurate, the installed insert will be within the required thread tolerance.


Rapi-Coil STI Thread Plug Gages (Metric) give the correct and accurate parameter to gage a tapped hole prior to installing the Screw Thread Wire Insert.


Our Gage handles and nibs are marked with the extreme product limits for the particular size and class of fit. For best results

the Gage should always be appropriately lubricated before gaging thoroughly cleaned tapped holes.


An installed Screw Thread Insert is not needed to be gaged as any gaged tapped hole will fit and wind the Insert most

perfectly and accurately.? After the insert is installed, the GO thread plug gage may not enter freely. The insert will always

seat itself when the bolt or screw is installed and tightened.


Specification :

BS 4377-1991 for ISO Metric Threads.


Rapi-Coil STI Thread Plug Gages (metric) for checking the tapped hole are listed below. The complete gage includes the GO thread plug gage, the HI thread plug gage and the appropriately marked gage handle.