Drill America POU1/2NPTW/DRILL, 1/2 in NPT tap and 23/32 in drill

Because the tapping drill size is what decides whether a thread holds or tears out, and it is the figure this hub’s introduction promises. Drill the hole too small and the tap jams and snaps; too large and there is not enough metal left to form a full thread, so it strips under load. For a 1/2 in NPT thread the tapping drill is 23/32 in, and this set simply puts the two together — which no other product in this hub, in either half, does for a single size.

Carbon steel here, and the listing is clear about what that means: the tap is "designed to clean and or re-thread damaged or Jam pipe threads". A carbon steel tap is softer than HSS, loses its edge sooner and will not hold up to cutting a new thread in solid steel — but for chasing rust and burrs out of an existing fitting it is adequate and cheap. For cutting new threads, the HSS-G sets in the European half of this hub are the tools.

It is tapered, by three quarters of an inch per foot. That is what makes a pipe joint seal: the thread wedges as it tightens, rather than relying on a flat face and a gasket. In practice it means the tap cannot simply be run through the hole — it is driven until the fitting sits at the right depth, and going too far leaves a joint that will not seal. The drill, by contrast, is a plain straight 23/32 in hole.