Metallics 1428CTBE Carbon Steel Tap Bottoming Type 1/4-28 (1pc)

It cuts a 1/4-28 thread, which is the UNF (fine) pitch for a 1/4 inch fastener, not the more common 1/4-20 coarse thread. If the screws or studs you are chasing are 1/4-20, this tap will not match them.

A bottoming tap has almost no lead taper, so it cuts threads nearly to the bottom of a blind hole. That makes the 1428CTBE the finishing tap, not the starting tap. In a blind hole you normally start the thread with a taper or plug tap and then run the bottoming tap in to carry the thread down to the base. In a through hole you usually don't need it at all.

Carbon steel. That suits hand tapping and thread chasing in mild steel, aluminum and brass on install and maintenance work. For powered tapping or harder alloys, an electrician or millwright would reach for a high speed steel tap instead, since carbon steel loses its edge faster under heat.

Yes, chasing an existing 1/4-28 thread is a normal job for it, and the bottoming grind lets you reach threads near the base of a blind tapped hole that a taper tap can't finish. Back it out frequently to clear chips, since a carbon steel tap is easy to snap if you force it.

One tap per pack, supplied in a pouch. If you are stocking a van or a shop crib and want spares on hand, order multiple pieces rather than expecting a set of taper, plug and bottoming styles in the package.

Order Metallics 1428CTBE. That is the single model offered for the carbon steel 1/4-28 bottoming tap, sold one piece per pouch.