In preparation of the lock nut of a certain manufacturer, we plan to screw the coupling with a lathe and to escape like a tap like a tap.
It takes time to thread threads because the thread groove is deep.
Since there is no JIS standard screw, there is no commercially available tap, and even if there is, it will cost 2.30 ten thousand taps. (Refer to the price of taps for piping)
So, I decided to process a thick coupling.
The grip of the tap will use piping iron pipe as it is.