Metallics 1224CTT Carbon Steel Tap Taper Type 12-24 (1pc)

A taper tap, which is what the 1224CTT is, has a long chamfered lead of several threads so it self-aligns and starts easily in a fresh hole. That lead means it will not cut full threads to the bottom of a blind hole. For through holes in panels, boxes and strut it is the right choice; if you need full threads at the base of a blind hole, you follow with a plug or bottoming tap in the same 12-24 size.

The 1224CTT is carbon steel. Carbon steel taps suit hand tapping in mild steel enclosures, sheet metal, aluminum and brass. They dull faster than high speed steel and are not intended for powered tapping or hard/stainless material, so keep it on a T-handle and use cutting oil.

Yes, chasing a buggered 12-24 hole is a common use. The tapered lead lets it pick up the existing thread without cross-threading. Back it out every half turn to clear chips, and note that a cutting tap removes metal, so if the hole is already stripped out it will not restore it and you will need a thread insert or a larger screw size.

One tap per pack, supplied in a pouch. If you are stocking a service van or a facility tool crib and expect to snap one mid-job, order a spare, since a broken tap in a tapped hole usually means drilling the hole oversize.