With the GSR Thread Calculator App it is possible to determine core hole dimensions and premachining diameters for various types of threads – without having to look up annoying tables.
The operation is intuitive and simple. Select the thread type, the nominal thread dimension and the pitch. And the desired core hole dimension appears. One more click and the app calculates the pre-machining diameter. An Android operating system (at least Ice Cream Sandwich 4.0.3) is required in your smartphone.