Metallics 3410CTB Carbon Steel Tap Bottoming Type 3/4-10 (1pc)

The 3410CTB cuts a 3/4-10 thread, meaning 3/4 inch diameter with 10 threads per inch, which is the standard UNC coarse pitch for that diameter. If your rod, bolt or threaded hanger is 3/4-10, this is the tap that will chase or cut the matching female thread.

A bottoming tap has almost no chamfer at the tip, so it threads nearly to the bottom of a blind hole. That also makes it poor at starting: it does not self-align or ease into the hole the way a taper tap does. Standard practice is to start the hole with a taper (and plug) tap, then finish with the bottoming tap like the 3410CTB to carry the 3/4-10 thread full depth. For a through hole you usually do not need a bottoming tap at all.

It is a carbon steel tap. Carbon steel holds an edge well in softer material, so it suits hand tapping and chasing threads in mild steel, aluminum, brass and similar. It will not take the heat and abuse of production machine tapping in hard or stainless material the way high speed steel does, so treat this as a hand tap: tap wrench, cutting oil, back it off to clear chips.

Yes, chasing damaged or painted-over 3/4-10 female threads is exactly where a bottoming tap earns its place, because it reaches threads near the closed end of a blind hole that a taper tap cannot. Common on 3/4-10 concrete inserts and hanger anchors for trapeze and conduit support. Use cutting oil and a tap wrench; the carbon steel body is meant to be turned by hand, not driven with an impact.

No. The 3410CTB cuts a straight 3/4-10 machine thread, not a tapered pipe thread. For 3/4 inch NPT you need a tapered pipe tap, which has a different pitch and taper and will not interchange. Trying to use this one on a pipe port will not produce a sealing thread.

One tap per pack, supplied in a pouch. If you are tapping a run of holes from scratch you will want a taper tap in the same 3/4-10 size alongside it, since the bottoming tap is the finishing tool rather than the starter.