Metallics 1420CTBE Carbon Steel Tap Bottoming Type 1/4-20 (1pc)

A bottoming tap has almost no lead chamfer, so it cuts full-depth threads right to the bottom of a blind hole. The 1420CTBE is the bottoming type, which is what you reach for after a taper or plug tap has started the hole, or when you need usable threads in the last turn or two of a hole that does not pass through. For starting a thread from scratch in an open hole, a taper tap enters easier.

Not well. Because it is a bottoming tap, the 1420CTBE has little or no taper at the nose, so it is hard to align and start in a bare hole. Use a taper tap first to establish the thread, then follow with this one to carry the threads to the bottom. In a through hole you usually do not need a bottoming tap at all.

Carbon steel. That suits hand tapping and thread chasing in mild steel, aluminum, and brass, which covers most electrical box, strut, and enclosure work. For production tapping or harder alloys, a high speed steel tap holds its edge longer.

One tap per order, supplied in a pouch. If you are stocking a van or a shop drawer and want a full taper, plug, and bottoming progression in 1/4-20, you order the other chamfer styles separately.

Yes, chasing buggered 1/4-20 threads is a normal use for it. Run it in by hand with cutting oil and back it off regularly to clear chips. Keep in mind it is a cutting tap, not a thread-restoring file, so if the hole is cross-threaded badly you may end up removing metal rather than reforming it.