1 3/8"-6 Taps | McMaster-Carr

Taper Chamfer—Good for both starting holes and threading through holes. These taps have the longest taper to gradually engage with the material, reducing the force needed to turn them. They can't reach the bottom of blind holes, however, so you will likely need to finish with a bottoming-chamfer tap.

Plug Chamfer—Our go-to chamfer type, these thread both through holes and blind holes. The tapered section is shorter than a taper chamfer and longer than bottoming chamfer. As a result, they're easier to turn than bottoming taps but require more force than taper taps.

Bottoming Chamfer—Cut all the way to the bottom of blind holes with taps that have the shortest taper. Since these require the most force to turn, they’re often used to finish holes started by taper- or plug-chamfer taps.

Number of Flutes—Taps with fewer flutes have more space to capture chips, so you won’t have to clear them as often. However, they can be more difficult to keep straight in the hole.

Taps Sold as Sets—Include one tap of each chamfer type.

	Taps														Taps Sold as Sets
						Drill Bit			Taper Chamfer		Plug Chamfer		Bottoming Chamfer
	Thread Size	Thread Lg.	Overall Lg.	Thread Type	No. of Flutes	Size	Decimal Size Equiv.	Shank Type		Each		Each		Each	No. of Taps		Each
High-Speed Steel







				Uncoated

				1 3/8"-6	3"	6 1/16"	UNC	4	1 7/32"	1.2188"	Square	2521A584	0000000	2521A634	0000000	2521A654	0000000	3	2521A784	0000000


				Carbon Steel







								Uncoated

								1 3/8"-6	3"	6 5/32"	UNC	4	1 7/32"	1.2188"	Square	26035A135	000000	26035A169	000000	26035A193	000000	—	———	0

Tap Sets

These sets include a variety of taps for threading holes so screws, bolts, and rods fit snugly.

High-Speed Steel—Single Thread Size Sets

Taper, Plug, and Bottoming

Chamfer Set

The most versatile taps resist heat and wear to stay sharp. They’re good for most metals and plastic. These sets include one of each chamfer type: Taper for starting holes and threading through holes; plug for through holes and blind holes; and bottoming for cutting the closest to the bottom of any hole.

Uncoated—The economical choice, these won't last as long as coated taps.

							Taper Chamfer, Plug Chamfer, Bottoming Chamfer
	No. of Pieces	Thread Size	Thread Type	Container Type	No. of Flutes	Shank Type		Each
Uncoated



		3	1 3/8"-6	UNC	Plastic Case	4	Square	2521A784	0000000

Carbon Steel—Single Thread Size Sets

Taper, Plug, and Bottoming

Chamfer Set

The economical choice for occasional hand tapping. These work on most metals and plastic but will dull more quickly than other taps. Sets include one each chamfer type: Taper for starting holes and through holes; plug for through holes and blind holes; and bottoming for cutting the closest to the bottom of any hole.

							Taper Chamfer, Plug Chamfer, Bottoming Chamfer
	No. of Pieces	Thread Size	Thread Type	Container Type	No. of Flutes	Shank Type		Each
Uncoated



		3	1 3/8"-6	UNC	Plastic Case	4	Square	26035A365	0000000

Helical Insert Taps

Match the size of helical inserts so they fit tightly when installed in the hole.

High-Speed Steel—These taps resist heat and wear to stay sharp.

						Drill Bit			Bottoming Chamfer
	For Insert Size	Thread Lg.	Overall Lg.	For Insert Thread Type	No. of Flutes	Size	Decimal Size Equiv.	Shank Type		Each
High-Speed Steel







				Uncoated

				1 3/8"-6	3 3/16"	6 11/16"	UNC	6	1 27/64"	1.4219"	Square	91709A512	0000000