Counterbore Sets | McMaster-Carr

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	For Use On For Use On

	Diameter Rating Diameter Rating

	Material Material

High-Speed Steel

Steel

	Number of Pieces Number of Pieces

	Shank Type Shank Type

	Round

	Number of Flutes Number of Flutes

	2		4

	Container Type Container Type

Plastic Case

Wood Case

Wood Stand

	Drill Tip Diameter Drill Tip Diameter

	DFARS (Defense Acquisition Regulations Supplement) DFARS (Defense Acquisition Regulations Supplement)

DFARS Specialty Metals
COTS-Exempt

	Pilot Length Pilot Length

	Shank Diameter Shank Diameter

	Maximum Hole Drilling Depth Maximum Hole Drilling Depth

	Body Diameter Body Diameter

	REACH (Registration, Evaluation, Authorization and Restriction of Chemicals) REACH (Registration, Evaluation, Authorization and Restriction of Chemicals)

REACH Compliant

	RoHS (Restriction of Hazardous Substances) RoHS (Restriction of Hazardous Substances)

RoHS Compliant

	Finish Finish

Uncoated

	Overall Length Overall Length

9 Products

About Counterbores

Counterboring—Enlarge the top of an existing hole to create a cylindrical-shaped opening with a flat bottom that acts as a seat for the head of a screw or wood plug.

The built-in pilot maintains alignment in the hole.

Uncoated High-Speed Steel
Sizes Included	Number of Pieces	Pilot Lg.	Number of Flutes	Flute Style	Shank Type	For Use On		Set
No. 4, No. 5, No. 6, No. 8, No. 10, 1/4", 3/8", 5/16", 7/16", 1/2"	10	0.156", 0.188", 0.219", 0.250", 0.281", 0.313", 0.375", 0.500"	4	Spiral	Round	Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel	0000000	0000000

Metric Size Counterbore Sets with Built-In Pilot

The counterbores in this set are oversized for counterboring screw holes in sheets or layers of material that are misaligned. All have a built-in pilot to maintain alignment in the hole.

Uncoated High-Speed Steel
Dia. Rating	Sizes Included	Number of Pieces	Pilot Lg.	Number of Flutes	Flute Style	Shank Type	For Use On		Set
0.5 mm Oversized	3 mm, 4 mm, 5 mm, 6 mm, 8 mm, 10 mm, 12 mm, 14 mm	8	0.218", 0.250", 0.281", 0.312", 0.375", 0.500", 0.562"	4	Spiral	Round	Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel	0000000	0000000

Oversized Counterbore Sets with Built-In Pilot

Use these oversized counterbore sets when the screw holes in sheets or layers of material are misaligned. They have a built-in pilot to maintain alignment in the hole.

Uncoated High-Speed Steel
Dia. Rating	Sizes Included	Number of Pieces	Pilot Lg.	Number of Flutes	Flute Style	Shank Type	For Use On		Set
1/64" Oversized	No. 4, No. 5, No. 6, No. 8, No. 10, 1/4", 5/16", 3/8", 7/16", 1/2"	10	0.156", 0.188", 0.219", 0.250", 0.281", 0.313", 0.375", 0.500"	4	Spiral	Round	Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel	0000000	0000000
1/32" Oversized	No. 4, No. 5, No. 6, No. 8, No. 10, 1/4", 5/16", 3/8", 7/16", 1/2"	10	0.156", 0.188", 0.219", 0.250", 0.281", 0.313", 0.375", 0.500"	4	Spiral	Round	Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel	0000000	000000

Metric Size Drill-Point Counterbore Sets

No need for separate tools, these sets have counterbores in various sizes that drill and counterbore holes with enough clearance for socket head cap screws. The longer the counterbore, the thicker the material it can drill.

		Diameter
Sizes Included	Number of Pieces	Body	Shank	Drill Tip	Overall Length	Maximum Hole Drilling Depth	Number of Flutes	Shank Type	For Use On	Container Type		Each
Uncoated High-Speed Steel
3 mm 4 mm 5 mm 6 mm 8 mm 10 mm 12 mm 14 mm 16 mm	9	5.95 mm 7.54 mm 9.13 mm 10.71 mm 13.49 mm 16.66 mm 18.75 mm 21.82 mm 24.6 mm	1/4" 1/4" 5/16" 5/16" 7/16" 1/2" 5/8" 5/8" 5/8"	3.57 mm 4.36 mm 5.55 mm 6.35 mm 8.73 mm 10.32 mm 12.7 mm 14.68 mm 16.67 mm	1 9/32" 1 13/32" 1 9/16" 1 5/8" 1 29/32" 2 5/32" 2 9/16" 2 27/32" 3 1/2"	6.35 mm 7.54 mm 7.94 mm 9.52 mm 11.11 mm 14.29 mm 15.87 mm 16.67 mm 17.46 mm	2	Round	Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel	Plastic Case	00000000	0000000

Inch Size Drill-Point Counterbore Sets

Keep counterbores in various sizes on hand to drill and counterbore holes with enough clearance for socket head cap screws without changing tools. The longer the counterbore, the thicker the material it can drill.

			Diameter
Sizes Included	Overall Length	Number of Pieces	Body	Shank	Drill Tip	Maximum Hole Drilling Depth	Number of Flutes	Shank Type	For Use On	Container Type		Each
Uncoated High-Speed Steel
No. 5 No. 6 No. 8 No. 10 1/4" 5/16" 3/8" 7/16" 1/2"	1 7/32" 1 7/32" 1 15/32" 1 1/2" 1 3/4" 1 15/16" 2 11/32" 2 1/2" 2 11/16"	9	0.22" 0.242" 0.29" 0.332" 0.406" 0.49" 0.593" 0.687" 0.781"	1/4" 1/4" 5/16" 5/16" 7/16" 1/2" 5/8" 5/8" 5/8"	0.138" 0.15" 0.178" 0.2" 0.28" 0.34" 0.406" 0.468" 0.532"	1/4" 1/4" 0.281" 0.312" 3/8" 3/8" 0.468" 1/2" 0.562"	2	Round	Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel	Plastic Case	00000000	0000000
No. 5 No. 6 No. 8 No. 10 1/4" 5/16" 3/8" 7/16" 1/2"	2" 2" 2 1/4" 2 1/4" 2 3/4" 3" 3 1/2" 4" 4 1/2"	9	0.22" 0.242" 0.29" 0.332" 0.406" 0.49" 0.593" 0.687" 0.781"	1/4" 1/4" 3/8" 3/8" 3/8" 1/2" 1/2" 1/2" 1/2"	0.138" 0.15" 0.178" 0.2" 0.28" 0.34" 0.406" 0.468" 0.532"	0.414" 0.45" 0.534" 0.6" 0.84" 1.02" 1.218" 1.404" 1.596"	2	Round	Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel	Plastic Case	00000000	000000

Changeable-Pilot Counterbore Sets

Change out the pilot to use the same tool to counterbore multiple diameters. Set includes 5 counterbores and 10 pilots.

Uncoated High-Speed Steel
Sizes Included	Number of Pieces	Includes	Shank Type	For Use On	Container Type		Set
1/4", 5/16", 3/8", 7/16", 1/2"	5	10 Pilots	Round	Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel	Wood Case	0000000	0000000

Drill-Bit Counterbore Sets

Convert standard jobbers’ or brad-point drill bits into counterboring drill bits for drilling and counterboring in one step.

For technical drawings and 3-D models, click on a part number.

Uncoated Steel
Sizes Included	Number of Pieces	For Use On	Container Type		Set
3/16", 1/4", 5/16", 3/8", 7/16", 1/2"	6	Plastic, Wood	Wood Stand	0000000	0000000

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