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    483 Products
    About Counterbores
    industrial info icon

    Create flat-bottomed holes, so your screw heads sit flush, recessed, or slightly raised.

    Pilot Type

    Counterbore Type

    Drill-Point Counterbores

    Skip a step when installing screws in metal. With a sharp point on the tip, these counterbores drill a pilot hole topped with a flat recess for the screw head. That's faster and more accurate than switching to a counterbore in between passes with your drill bit.
    High-Speed SteelAbout High-Speed Steel
    Image of Product. Front orientation. Counterbores. Drill-Point Counterbores.
    Durable and wear resistant, these counterbores make accurate cuts in most materials without chipping or cracking.
    Shank
    Uncoated
    For Screw
    Size
    Body
    Dia.
    Drill Tip
    Dia.
    Overall
    Lg.
    Dia.
    Type
    No. of
    Flutes
    Max. Hole
    Drilling Dp.
    Mfr.
    Each
    No. 5
    		0.220"0.138"1 7/32"1/4"Round20.25"Link Industries29445A11000000
    No. 5
    		0.220"0.138"2"1/4"Round20.414"Link Industries29445A31100000
    No. 6
    		0.242"0.15"1 7/32"1/4"Round20.25"Link Industries29445A1200000
    No. 6
    		0.242"0.15"2"1/4"Round20.45"Link Industries29445A31200000
    No. 8
    		0.290"0.178"1 15/32"5/16"Round20.281"Link Industries29445A1300000
    No. 8
    		0.290"0.178"2 1/4"3/8"Round20.534"Link Industries29445A31300000
    No. 10
    		0.332"0.2"1 1/2"5/16"Round20.312"Link Industries29445A1400000
    No. 10
    		0.332"0.2"2 1/4"3/8"Round20.6"Link Industries29445A31400000
    1/4"
    		0.406"0.28"1 3/4"7/16"Round20.375"Link Industries29445A1500000
    1/4"
    		0.406"0.28"2 3/4"3/8"Round20.84"Link Industries29445A31500000
    5/16"
    		0.490"0.34"1 15/16"1/2"Round20.375"Link Industries29445A1600000
    5/16"
    		0.490"0.34"3"1/2"Round21.02"Link Industries29445A31600000
    3/8"
    		0.593"0.406"2 11/32"5/8"Round20.468"Link Industries29445A1700000
    3/8"
    		0.593"0.406"3 1/2"1/2"Round21.218"Link Industries29445A31700000
    7/16"
    		0.687"0.468"2 1/2"5/8"Round20.5"Link Industries29445A1800000
    7/16"
    		0.687"0.468"4"1/2"Round21.404"Link Industries29445A31800000
    1/2"
    		0.781"0.532"2 11/16"5/8"Round20.562"Link Industries29445A1900000
    1/2"
    		0.781"0.532"4 1/2"1/2"Round21.596"Link Industries29445A319000000
    M3
    		5.9 mm3.57 mm1 1/4"1/4"Round26.35 mmLink Industries29445A2100000
    M4
    		7.5 mm4.36 mm1 3/8"1/4"Round27.54 mmLink Industries29445A2200000
    M5
    		9.1 mm5.55 mm1 1/2"5/16"Round27.94 mmLink Industries29445A2300000
    M6
    		10.7 mm6.35 mm1 9/16"5/16"Round29.52 mmLink Industries29445A2400000
    M8
    		13.4 mm8.73 mm1 13/16"7/16"Round211.11 mmLink Industries29445A2500000
    M10
    		16.6 mm10.32 mm2 1/16"1/2"Round214.29 mmLink Industries29445A2600000
    M12
    		18.7 mm12.7 mm2 7/16"5/8"Round215.87 mmLink Industries29445A2700000
    M14
    		21.8 mm14.68 mm2 5/8"5/8"Round216.67 mmLink Industries29445A2800000
    M16
    		24.6 mm16.67 mm2 3/4"5/8"Round217.46 mmLink Industries29445A2900000
     

    Quick-Change Hex Drill-Bit Counterbores for Wood

    Image of ProductInUse. Shown with Optional Drill Stop (Sold Separately). Front orientation. Counterbores. Quick-Change Hex Drill-Bit Counterbores for Wood.

    Shown with Optional Drill

    Stop (Sold Separately)

    Pop the 1/4" hex shank into a drill chuck, power screwdriver, or impact driver to drill and counterbore a hole in a single step. These counterbores move along the included drill bit and lock into place with set screws to match the length of the screw you're installing.
    SteelAbout Steel
    Image of Product. Front orientation. Counterbores. Quick-Change Hex Drill-Bit Counterbores for Wood.
    Image of Product. Front orientation. Countersink and Counterbore Depth Stops.

    Depth Stops

    Depth Stops—Attach with a set screw to stop the counterbore at the exact depth you need.
    Counterbores
    Depth Stops
    Replacement
    Drill Bits
    Shank
    Black Oxide
    Body
    Dia.
    Drill Bit
    Size
    Overall
    Lg.
    Size
    Type
    No. of
    Flutes
    Max. Hole
    Drilling Dp.
    Mfr.
    Each
    Each
    Each
    3/8"1/8"
    		2 7/8"1/4"Quick-Change Hex31.1"Make It Snappy Tools3438N210000003438N110000002908A3500000
    1/2"1/8"
    		2 7/8"1/4"Quick-Change Hex31.2"Make It Snappy Tools3438N22000003438N11000002908A350000
    5/8"3/16"
    		3 1/4"1/4"Quick-Change Hex31.3"Make It Snappy Tools3438N2300000———02908A390000
    5/8"1/4"
    		3 21/32"1/4"Quick-Change Hex32.7"Make It Snappy Tools3438N31100000———02908A440000
    3/4"3/16"
    		3 1/4"1/4"Quick-Change Hex31.3"Make It Snappy Tools3438N2400000———02908A390000
    3/4"1/4"
    		3 5/8"1/4"Quick-Change Hex31.6"Make It Snappy Tools3438N2500000———02908A440000
    3/4"5/16"
    		3 31/32"1/4"Quick-Change Hex33"Make It Snappy Tools3438N31200000———02908A4800000
    1"7/16"
    		4 11/16"1/4"Quick-Change Hex33.7"Make It Snappy Tools3438N31300000———02908A5700000
     

    Drill-Bit Counterbores for Wood

    Image of ProductInUse. Shown with Drill Bit (Sold Separately). Front orientation. Counterbores. Drill-Bit Counterbores for Wood.

    Shown with Drill Bit (Sold

    Separately)

    Drill and counterbore holes of different depths without changing tools. These counterbores move along the drill bit (sold separately) and lock into place with set screws to match the length of the screw you're installing.
    SteelAbout Steel
    Image of Product. Front orientation. Counterbores. Drill-Bit Counterbores for Wood.
    Image of Product. Front orientation. Countersink and Counterbore Depth Stops.

    Depth Stops

    Depth Stops—Attach with a set screw to stop the counterbore at the exact depth you need.
    Counterbores
    Depth Stops
    Uncoated
    Body
    Dia.
    Drill Bit
    Size
    Overall
    Lg.
    No. of
    Flutes
    Mfr.
    Each
    Each
    5/8"3/16"1"4W. L. Fuller3105A110000002903A1700000
    5/8"1/4"1"4W. L. Fuller3105A21000002903A170000
    3/4"1/4"1"4W. L. Fuller3105A12000002903A180000
    3/4"5/16"1 1/8"4W. L. Fuller3105A13000002903A180000
    7/8"3/8"1 1/4"4W. L. Fuller3105A14000002903A190000
    1"7/16"1 3/8"4W. L. Fuller3105A15000002903A210000
    1 1/8"1/2"1 1/2"4W. L. Fuller3105A16000002903A320000
    1 1/4"9/16"1 5/8"4W. L. Fuller3105A22000002903A230000
     

    Drill-Point Counterbore Sets

    Image of Product. Front orientation. Counterbores. Drill-Point Counterbore Sets.
    Skip a step when installing screws of various thread diameters in metal. With a sharp point on the tip, these counterbores drill a pilot hole topped with a flat recess for the screw head. That's faster and more accurate than switching to a counterbore in between passes with your drill bit.
    High-Speed Steel—Durable and wear resistant, these counterbores make accurate cuts in most materials without chipping or cracking.
    For Screw Size
    Overall Length
    Shank
    Type
    No. of
    Flutes
    No. of
    Pieces
    Container
    Type
    Mfr.
    Each
    Uncoated High-Speed Steel
    No. 5, No. 6, No. 8, No. 10, 1/4", 5/16", 3/8", 7/16", 1/2"
    		1.21875", 1.21875", 1.46875", 1.5", 1.75", 1.9375", 2.34375", 2.5", 2.6875"Round29Plastic CaseLink Industries9940N1110000000
    No. 5, No. 6, No. 8, No. 10, 1/4", 5/16", 3/8", 7/16", 1/2"
    		2", 2", 2.25", 2.25", 2.75", 3", 3.5", 4", 4.5"Round29Plastic CaseLink Industries9940N112000000
    M3, M4, M5, M6, M8, M10, M12, M14, M16
    		1.28125", 1.40625", 1.5625", 1.625", 1.90625", 2.15625", 2.5625", 2.84375", 3.5"Round29Plastic CaseLink Industries9940N113000000
     

    Drill-Bit Counterbore Sets for Wood

    Image of Product. Front orientation. Counterbores. Drill-Bit Counterbore Sets for Wood.
    Drill and counterbore holes of different depths without changing tools. These counterbores move along the drill bit (sold separately) and lock into place with set screws to match the length of the screw you're installing.
    Body Dia.
    For Drill Bit Size
    No. of
    Pieces
    Container
    Type
    Mfr.
    Each
    Uncoated Steel
    5/8", 3/4", 7/8", 1", 1 1/8"3/16", 1/4", 5/16", 3/8", 7/16", 1/2"6Wood StandW. L. Fuller3105A310000000
     

    Adjustable-Diameter Counterbores

    Skip buying different tools to counterbore multiple diameters. Use the set screw on these counterbores to adjust the blades to the diameter you need.
    The included replaceable pilot has the minimum pilot head diameter recommended for use with these counterbores. If your application requires a larger pilot head diameter, choose a different pilot with the same shank diameter as the included pilot. These counterbores require rigid tool holding to prevent breakage and are not for use with hand-held tools.
    High-Speed Steel Blade
    Image of Product. Front orientation. Counterbores. Adjustable-Diameter Counterbores, Round Shank.
    Image of Product. Front orientation. Counterbores. Adjustable-Diameter Counterbores, Morse Taper Shank.

    Round Shank

    Morse Taper Shank

    Durable and wear resistant, these blades make accurate cuts in most materials without chipping or cracking.
    Counterbores
    Replacement
    Counterbore Blades
    Shank
    Body Dia.
    Overall
    Lg.
    Dia.
    Type
    Machine
    Taper No.
    Pilot
    Lg.
    No. of
    Flutes
    Pilot Head
    Dia.
    Pilot Shank
    Dia.
    Mfr.
    Each
    Pkg.
    Qty.
    Pkg.
    1" to 1 1/4"4"1/2"Round—0.438"27/16"3/16"Alvord-Polk Tool3104A11000000023104A310000000
    1 1/4" to 1 5/8"4 3/8"1/2"Round—0.563"29/16"1/4"Alvord-Polk Tool3104A1400000023104A32000000
    2 1/8" to 2 7/8"6"—Morse TaperMorse 30.750"23/4"3/8"Alvord-Polk Tool3104A2200000023104A34000000

    Built-in-Pilot Counterbores

    A pilot centers these counterbores and prevents wobbling for an accurate cut on the first try. With dimensions that match standard screw-head diameters and thread diameters, they are your plug-and-play option for pilot-driven counterbores.
    Metric counterbores have undersized pilots to meet DIN standards.
    High-Speed SteelAbout High-Speed Steel
    Image of Product. Front orientation. ZoomedIn view. Counterbores. Built-in-Pilot Counterbores.
    Durable and wear resistant, these counterbores make accurate cuts in most materials without chipping or cracking.
    Titanium Nitride (TiN) Coated—Withstand heat, corrosion, and abrasion for longer than uncoated counterbores, so the cutting edges stay sharper.
    Pilot
    Shank
    Uncoated
    Titanium Nitride
    (TiN) Coated
    For Screw
    Size
    Body
    Dia.
    Dia.
    Lg.
    Overall
    Lg.
    Dia.
    Type
    No. of
    Flutes
    Mfr.
    Each
    Each
    No. 4
    		0.186"0.112"0.156"3 7/8"5/32"Round4Alvord-Polk Tool2919A3100000028225A31000000
    No. 5
    		0.205"1/8"0.188"4 1/8"3/16"Round4Alvord-Polk Tool2919A320000028225A3200000
    No. 6
    		0.228"0.138"0.219"4 5/8"7/32"Round4Alvord-Polk Tool2919A330000028225A3300000
    No. 8
    		0.272"0.164"0.250"5"1/4"Round4Alvord-Polk Tool2919A340000028225A3400000
    No. 10
    		0.314"0.19"0.281"5 1/4"9/32"Round4Alvord-Polk Tool2919A350000028225A3500000
    1/4"
    		0.382"1/4"0.313"5 5/8"5/16"Round4Alvord-Polk Tool2919A360000028225A3600000
    5/16"
    		0.475"5/16"0.375"6 1/8"3/8"Round4Alvord-Polk Tool2919A370000028225A3700000
    3/8"
    		0.572"3/8"0.500"6 1/2"1/2"Round4Alvord-Polk Tool2919A380000028225A3800000
    7/16"
    		0.663"7/16"0.500"7"1/2"Round4Alvord-Polk Tool2919A390000028225A39000000
    1/2"
    		0.757"1/2"0.500"7 1/2"1/2"Round4Alvord-Polk Tool2919A410000028225A41000000
    5/8"
    		0.945"5/8"0.625"7 5/8"5/8"Round4Alvord-Polk Tool2919A4200000028225A42000000
    3/4"
    		1.133"3/4"0.750"7 3/4"3/4"Round4Alvord-Polk Tool2919A4300000028225A43000000
    7/8"
    		1.322"7/8"0.875"8 1/8"7/8"Round4Alvord-Polk Tool2919A4700000028225A44000000
    1"
    		1.510"1"1.000"8 1/2"1"Round4Alvord-Polk Tool2919A4500000028225A45000000
    M4
    		8.0 mm3.3 mm0.197"2 3/4"3/16"Round3Dormer Pramet2919A2700000———0
    M5
    		10.0 mm4.2 mm0.217"3 1/8"5/16"Round3Dormer Pramet2919A2800000———0
    M6
    		11.0 mm5.0 mm0.236"3 1/8"5/16"Round3Dormer Pramet2919A2900000———0
    M8
    		15.0 mm6.8 mm0.315"3 7/8"1/2"Round3Dormer Pramet2919A9700000———0
    M10
    		18.0 mm8.5 mm0.394"3 7/8"1/2"Round3Dormer Pramet2919A9800000———0
    M12
    		20.0 mm10.2 mm0.394"3 7/8"1/2"Round3Dormer Pramet2919A9900000———0
     
    Cobalt SteelAbout Cobalt Steel
    Image of Product. Front orientation. ZoomedIn view. Counterbores. Built-in-Pilot Counterbores.
    Tougher and more wear resistant than high-speed steel counterbores, these counterbores last at least twice as long. They can also run up to 25% faster at higher temperatures without chipping on hard materials, such as nickel.
    Pilot
    Shank
    Uncoated
    For Screw
    Size
    Body
    Dia.
    Dia.
    Lg.
    Overall
    Lg.
    Dia.
    Type
    No. of
    Flutes
    Mfr.
    Each
    No. 4
    		0.186"0.112"0.188"3"5/32"Round3Keo11162N11000000
    No. 6
    		0.228"0.138"0.203"3"7/32"Round3Keo11162N1300000
    No. 8
    		0.272"0.164"0.250"3"1/4"Round3Keo11162N1400000
    No. 10
    		0.314"0.19"0.266"4 1/2"9/32"Round3Keo11162N1500000
    1/4"
    		0.382"1/4"0.313"4 1/2"5/16"Round3Keo11162N1600000
    5/16"
    		0.475"5/16"0.359"4 1/2"3/8"Round3Keo11162N1700000
    3/8"
    		0.572"3/8"0.500"5"1/2"Round3Keo11162N1800000
    1/2"
    		0.757"1/2"0.500"6"1/2"Round3Keo11162N21000000
     
    Carbide-Tipped Steel
    Image of Product. Front orientation. ZoomedIn view. Counterbores. Built-in-Pilot Counterbores.
    The hardest and most wear-resistant counterbores we offer. These bits stay sharper at higher temperatures and faster speeds for the best performance on hard and abrasive materials.
    Pilot
    Shank
    Uncoated
    For Screw
    Size
    Body
    Dia.
    Dia.
    Lg.
    Overall
    Lg.
    Dia.
    Type
    No. of
    Flutes
    Mfr.
    Each
    1/4"
    		0.382"1/4"0.313"5 5/8"5/16"Round3Rock River Tool3218A1110000000
    5/16"
    		0.475"5/16"0.375"6 1/8"3/8"Round3Rock River Tool3218A121000000
    3/8"
    		0.572"3/8"0.500"6 1/2"1/2"Round3Rock River Tool3218A131000000
    7/16"
    		0.663"7/16"0.500"7"1/2"Round3Rock River Tool3218A141000000
    1/2"
    		0.757"1/2"0.500"7 1/2"1/2"Round3Rock River Tool3218A151000000
    5/8"
    		0.945"5/8"0.625"7 5/8"5/8"Round3Rock River Tool3218A161000000
    3/4"
    		1.133"3/4"0.750"7 3/4"3/4"Round3Rock River Tool3218A171000000
    7/8"
    		1.322"7/8"0.875"8 1/8"7/8"Round4Rock River Tool3218A181000000
    1"
    		1.510"1"1.000"8 1/2"1"Round4Rock River Tool3218A191000000
     

    Changeable-Pilot Counterbores

    Image of ProductInUse. Shown with Pilot (Sold Separately). Front orientation. Counterbores. Changeable-Pilot Counterbores.

    Shown with Pilot (Sold Separately)

    A popular choice when counterboring for nonstandard screw sizes, this tool creates counterbored holes for screws of various thread diameters. Attach a pilot (sold separately) that matches the diameter of your pilot hole. The pilot centers the counterbore and prevents wobbling to create an accurate recess for the screw head on the first try.
    High-Speed SteelAbout High-Speed Steel
    Image of Product. Front orientation. Counterbores. Changeable-Pilot Counterbores, Round Shank.
    Image of Product. Front orientation. Counterbores. Changeable-Pilot Counterbores, Reduced-Round Shank.

    Round Shank

    Reduced-Round Shank

    Durable and wear resistant, these counterbores make accurate cuts in most materials without chipping or cracking.
    Shank
    Uncoated
    Body
    Dia.
    Overall
    Lg.
    For Pilot
    Shank Dia.
    Dia.
    Type
    No. of
    Flutes
    Mfr.
    Each
    3/16"3"3/32"15/64"Round3Cleveland3015A110000000
    7/32"3"3/32"15/64"Round3Cleveland3015A12000000
    1/4"2 3/8"3/32"1/4"Reduced Round4Mist Cutting Tools3102A1100000
    1/4"3 13/16"3/32"15/64"Round3F&D Tool3015A1300000
    9/32"2 3/8"3/32"1/4"Reduced Round4Mist Cutting Tools3102A1200000
    9/32"3 13/16"3/32"17/64"Round3F&D Tool3015A1400000
    5/16"2 3/8"3/32"1/4"Reduced Round4Mist Cutting Tools3102A1300000
    5/16"3 13/16"3/32"19/64"Round3F&D Tool3015A1500000
    11/32"2 3/8"3/32"1/4"Reduced Round4Mist Cutting Tools3102A1400000
    11/32"3 13/16"3/32"5/16"Round3F&D Tool3015A1600000
    3/8"2 3/8"3/32"1/4"Reduced Round4Mist Cutting Tools3102A1500000
    3/8"4 1/16"5/32"5/16"Round3F&D Tool3015A1700000
    13/32"2 13/16"1/8"1/4"Reduced Round4Mist Cutting Tools3102A1600000
    13/32"4 1/16"5/32"3/8"Round3F&D Tool3015A1800000
    7/16"2 13/16"1/8"1/4"Reduced Round4Mist Cutting Tools3102A1700000
    7/16"4 1/16"5/32"3/8"Round3F&D Tool3015A1900000
    15/32"2 13/16"1/8"1/4"Reduced Round4Mist Cutting Tools3102A1800000
    15/32"4 5/16"3/16"7/16"Round3F&D Tool3015A2100000
    1/2"2 13/16"1/8"1/4"Reduced Round4Mist Cutting Tools3102A1900000
    1/2"4 5/16"3/16"7/16"Round3F&D Tool3015A2200000
    17/32"2 13/16"1/8"1/4"Reduced Round4Mist Cutting Tools3102A2100000
    17/32"4 5/16"3/16"1/2"Round3F&D Tool3015A2300000
    9/16"2 13/16"1/8"1/4"Reduced Round4Mist Cutting Tools3102A2200000
    9/16"4 5/16"3/16"1/2"Round3F&D Tool3015A2400000
    19/32"2 13/16"1/8"1/4"Reduced Round4Mist Cutting Tools3102A2300000
    19/32"5 1/8"3/16"1/2"Round3F&D Tool3015A2500000
    5/8"2 13/16"1/8"1/4"Reduced Round4Mist Cutting Tools3102A2400000
    5/8"5 1/8"3/16"1/2"Round3F&D Tool3015A2600000
    21/32"3 1/8"3/16"1/4"Reduced Round4Mist Cutting Tools3102A2500000
    21/32"5 1/8"3/16"1/2"Round3F&D Tool3015A2700000
    11/16"3 1/8"3/16"1/4"Reduced Round4Mist Cutting Tools3102A2600000
    11/16"5 1/8"3/16"1/2"Round3F&D Tool3015A2800000
    23/32"3 1/8"3/16"1/4"Reduced Round4Mist Cutting Tools3102A2700000
    23/32"5 3/8"1/4"1/2"Round3F&D Tool3015A2900000
    3/4"3 1/8"3/16"1/4"Reduced Round4Mist Cutting Tools3102A2800000
    3/4"5 3/8"1/4"1/2"Round3F&D Tool3015A3100000
    25/32"3 1/8"3/16"1/4"Reduced Round4Mist Cutting Tools3102A2900000
    25/32"5 1/8"1/4"5/8"Round3F&D Tool3015A3200000
    13/16"3 1/8"3/16"1/4"Reduced Round4Mist Cutting Tools3102A3100000
    13/16"5 1/8"1/4"5/8"Round3F&D Tool3015A33000000
    7/8"3 1/8"3/16"1/4"Reduced Round4Mist Cutting Tools3102A3300000
    7/8"5 3/8"1/4"3/4"Round3F&D Tool3015A34000000
    15/16"3 1/8"3/16"1/4"Reduced Round4Mist Cutting Tools3102A35000000
    15/16"6 1/8"1/4"3/4"Round3F&D Tool3015A43000000
    1"3 1/8"3/16"1/4"Reduced Round4Mist Cutting Tools3102A37000000
    1"6 3/8"5/16"3/4"Round3F&D Tool3015A36000000
    1 1/8"6 3/8"5/16"1"Round3F&D Tool3015A38000000
     
    Counterbore Pilots
    Image of Product. Front orientation. Counterbore Pilots.
    Pilot Head
    Dia.
    Pilot
    Lg.
    Each
    Uncoated Carbon Steel
     
    3/32" Diameter Pilot Shank
    3/32"3/32"3103A100000
    1/8"1/8"3103A110000
    5/32"5/32"3103A120000
    3/16"3/16"3103A130000
    7/32"7/32"3103A140000
    1/4"1/4"3103A150000
     
    1/8" Diameter Pilot Shank
    1/8"1/8"3103A160000
    5/32"5/32"3103A170000
    3/16"3/16"3103A180000
    7/32"7/32"3103A190000
    1/4"1/4"3103A20000
    5/16"5/16"3103A2100000
    3/8"3/8"3103A2200000
     
    5/32" Diameter Pilot Shank
    3/16"3/16"3103A230000
    7/32"7/32"3103A2400000
    1/4"1/4"3103A250000
    9/32"9/32"3103A6100000
    5/16"5/16"3103A2600000
    3/8"3/8"3103A2700000
     
    3/16" Diameter Pilot Shank
    3/16"3/16"3103A640000
    1/4"1/4"3103A280000
    9/32"9/32"3103A6200000
    5/16"5/16"3103A2900000
    11/32"11/32"3103A6300000
    3/8"3/8"3103A300000
    13/32"13/32"3103A6500000
    7/16"7/16"3103A3100000
    15/32"15/32"3103A6600000
    1/2"1/2"3103A3200000
    17/32"17/32"3103A4800000
    9/16"9/16"3103A3300000
    5/8"5/8"3103A3400000
     
    1/4" Diameter Pilot Shank
    5/16"5/16"3103A350000
    3/8"3/8"3103A3600000
    7/16"7/16"3103A3700000
    1/2"1/2"3103A3800000
    9/16"9/16"3103A3900000
    5/8"5/8"3103A400000
    11/16"11/16"3103A4100000
    3/4"3/4"3103A4200000
    13/16"13/16"3103A4300000
     
    5/16" Diameter Pilot Shank
    3/8"3/8"3103A4500000
    7/16"7/16"3103A4600000
    1/2"1/2"3103A4700000
    5/8"5/8"3103A4900000
    11/16"11/16"3103A500000
    3/4"3/4"3103A5100000
    1"1"3103A5500000
     
    Carbide-Tipped Steel
    Image of Product. Front orientation. Counterbores. Changeable-Pilot Counterbores, Round Shank.
    Image of Product. Front orientation. Counterbores. Changeable-Pilot Counterbores, Reduced-Round Shank.

    Round Shank

    Reduced-Round Shank

    The hardest and most wear-resistant counterbores we offer. These bits stay sharper at higher temperatures and faster speeds for the best performance on hard and abrasive materials.
    Shank
    Uncoated
    Body
    Dia.
    Overall
    Lg.
    For Pilot
    Shank Dia.
    Dia.
    Type
    No. of
    Flutes
    Mfr.
    Each
    1/4"2 3/8"3/32"1/4"Reduced Round3Rock River Tool31125A21000000
    1/4"3 13/16"3/32"15/64"Round3Rock River Tool2814A81000000
    9/32"2 3/8"3/32"1/4"Reduced Round3Rock River Tool31125A2200000
    9/32"3 13/16"3/32"17/64"Round3Rock River Tool2814A421000000
    5/16"2 3/8"3/32"1/4"Reduced Round3Rock River Tool31125A2300000
    5/16"3 13/16"3/32"19/64"Round3Rock River Tool2814A591000000
    11/32"2 3/8"3/32"1/4"Reduced Round3Rock River Tool31125A2400000
    11/32"3 13/16"3/32"5/16"Round3Rock River Tool2814A311000000
    3/8"2 3/8"3/32"1/4"Reduced Round3Rock River Tool31125A2500000
    3/8"4 1/16"5/32"5/16"Round3Rock River Tool2814A83000000
    13/32"2 3/4"1/8"1/4"Reduced Round3Rock River Tool31125A2600000
    13/32"4 1/16"5/32"3/8"Round3Rock River Tool2814A321000000
    7/16"2 3/4"1/8"1/4"Reduced Round3Rock River Tool31125A2700000
    7/16"4 1/16"5/32"3/8"Round3Rock River Tool2814A84000000
    15/32"2 3/4"1/8"1/4"Reduced Round3Rock River Tool31125A2800000
    15/32"4 5/16"3/16"7/16"Round3Rock River Tool2814A331000000
    1/2"2 3/4"1/8"1/4"Reduced Round3Rock River Tool31125A2900000
    1/2"4 5/16"3/16"7/16"Round3Rock River Tool2814A85000000
    17/32"2 3/4"1/8"1/4"Reduced Round3Rock River Tool31125A3100000
    17/32"4 5/16"3/16"1/2"Round3Rock River Tool2814A341000000
    9/16"2 3/4"1/8"1/4"Reduced Round3Rock River Tool31125A32000000
    9/16"4 5/16"3/16"1/2"Round3Rock River Tool2814A86000000
    19/32"2 3/4"1/8"1/4"Reduced Round3Rock River Tool31125A33000000
    19/32"5 1/8"3/16"1/2"Round3Rock River Tool2814A351000000
    5/8"2 3/4"1/8"1/4"Reduced Round3Rock River Tool31125A34000000
    5/8"5 1/8"3/16"1/2"Round3Rock River Tool2814A87000000
    21/32"2 3/4"3/16"1/4"Reduced Round3Rock River Tool31125A35000000
    21/32"5 1/8"3/16"1/2"Round3Rock River Tool2814A361000000
    11/16"2 3/4"3/16"1/4"Reduced Round3Rock River Tool31125A36000000
    11/16"5 1/8"3/16"1/2"Round3Rock River Tool2814A371000000
    23/32"2 3/4"3/16"1/4"Reduced Round3Rock River Tool31125A37000000
    23/32"5 3/8"1/4"1/2"Round3Rock River Tool2814A381000000
    3/4"2 3/4"3/16"1/4"Reduced Round3Rock River Tool31125A38000000
    3/4"5 3/8"1/4"1/2"Round3Rock River Tool2814A89000000
    25/32"2 3/4"3/16"1/4"Reduced Round3Rock River Tool31125A39000000
    25/32"5 3/8"1/4"5/8"Round3Rock River Tool2814A391000000
    13/16"2 3/4"3/16"1/4"Reduced Round3Rock River Tool31125A41000000
    13/16"5 3/8"1/4"5/8"Round3Rock River Tool2814A91000000
    7/8"2 3/4"3/16"1/4"Reduced Round3Rock River Tool31125A43000000
    7/8"5 3/8"1/4"3/4"Round3Rock River Tool2814A531000000
    15/16"2 3/4"3/16"1/4"Reduced Round3Rock River Tool31125A45000000
    15/16"6 1/8"1/4"3/4"Round3Rock River Tool2814A561000000
    1"2 3/4"3/16"1/4"Reduced Round3Rock River Tool31125A47000000
    1"6 3/8"5/16"3/4"Round3Rock River Tool2814A94000000
    1 1/8"6 3/8"5/16"1"Round3Rock River Tool2814A581000000
     
    Counterbore Pilots
    Image of Product. Front orientation. Counterbore Pilots.
    Pilot Head
    Dia.
    Pilot
    Lg.
    Each
    Uncoated Carbon Steel
     
    3/32" Diameter Pilot Shank
    3/32"3/32"3103A100000
    1/8"1/8"3103A110000
    5/32"5/32"3103A120000
    3/16"3/16"3103A130000
    7/32"7/32"3103A140000
    1/4"1/4"3103A150000
     
    1/8" Diameter Pilot Shank
    1/8"1/8"3103A160000
    5/32"5/32"3103A170000
    3/16"3/16"3103A180000
    7/32"7/32"3103A190000
    1/4"1/4"3103A20000
    5/16"5/16"3103A2100000
    3/8"3/8"3103A2200000
     
    5/32" Diameter Pilot Shank
    3/16"3/16"3103A230000
    7/32"7/32"3103A2400000
    1/4"1/4"3103A250000
    9/32"9/32"3103A6100000
    5/16"5/16"3103A2600000
    3/8"3/8"3103A2700000
     
    3/16" Diameter Pilot Shank
    3/16"3/16"3103A640000
    1/4"1/4"3103A280000
    9/32"9/32"3103A6200000
    5/16"5/16"3103A2900000
    11/32"11/32"3103A6300000
    3/8"3/8"3103A300000
    13/32"13/32"3103A6500000
    7/16"7/16"3103A3100000
    15/32"15/32"3103A6600000
    1/2"1/2"3103A3200000
    17/32"17/32"3103A4800000
    9/16"9/16"3103A3300000
    5/8"5/8"3103A3400000
     
    1/4" Diameter Pilot Shank
    5/16"5/16"3103A350000
    3/8"3/8"3103A3600000
    7/16"7/16"3103A3700000
    1/2"1/2"3103A3800000
    9/16"9/16"3103A3900000
    5/8"5/8"3103A400000
    11/16"11/16"3103A4100000
    3/4"3/4"3103A4200000
    13/16"13/16"3103A4300000
     
    5/16" Diameter Pilot Shank
    3/8"3/8"3103A4500000
    7/16"7/16"3103A4600000
    1/2"1/2"3103A4700000
    5/8"5/8"3103A4900000
    11/16"11/16"3103A500000
    3/4"3/4"3103A5100000
    1"1"3103A5500000
     

    Coolant-Fed Port Counterbores

    Deliver coolant to port holes as you cut to reduce heat and flush out chips. These port counterbores work in CNC machines that supply coolant through the spindle. A pilot guides the counterbore as it finishes the hole to the exact size you need for your fitting. These counterbores meet aerospace and military specifications for leakproof port holes, so fittings stay sealed over time, even during sudden pressure and vibration.
    You’ll need a step drill bit (sold separately) to rough out a hole with the right shape for your counterbore to finish. To complete your hole with threads, add a thread mill (sold separately).
    Carbide-Tipped Steel
    Image of Product. Front orientation. Counterbores. Coolant-Fed Port Counterbores.
    The hardest and most wear-resistant counterbores we offer. They stay sharp at high temperatures and fast speeds to machine port holes with ease in aluminum, steel, and other metals.
    Counterbores
    Step Drill Bits
    Thread Mills
    Shank
    Uncoated
    For Thread
    Size
    For Port
    Dash Size
    Overall
    Lg.
    Dia.
    Lg.
    Type
    No. of
    Flutes
    Pilot
    Lg.
    Mil.
    Spec.
    Mfr.
    Each
    Each
    Each
    SAE J1926/1
    7/16"-20
    		043 1/2"1/2"2"Round30.551"MS16142Everede Tool9833N1100000009851N1300000005277N260000000
    9/16"-18
    		063 1/2"1/2"2"Round30.610"MS16142Everede Tool9833N120000009851N150000005277N28000000
    3/4"-16
    		083 1/2"3/4"2"Round30.689"MS16142Everede Tool9833N130000009851N160000005277N29000000
     
    SAE AS5202
    7/16"-20
    		043 1/2"1/2"2"Round30.661"MS33649Everede Tool9833N140000009851N230000005277N26000000
    9/16"-18
    		063 1/2"1/2"2"Round30.714"MS33649Everede Tool9833N150000009851N250000005277N28000000
    3/4"-16
    		084"3/4"2"Round30.839"MS33649Everede Tool9833N160000009851N260000005277N29000000
     

    Counterbores for High-Profile Rounded-Head Screws

    Cut flat, close-fitting recesses for fillister-head screws. These counterbores cut deeply enough for screws with tall head profiles to sit flush with the surface.
    High-Speed SteelAbout High-Speed Steel
    Image of Product. Front orientation. Counterbores. Counterbores for High-Profile Rounded-Head Screws.
    Durable and wear resistant, these counterbores make accurate cuts in most materials without chipping or cracking.
    Uncoated
    For Screw
    Size
    Body
    Dia.
    Overall
    Lg.
    Shank
    Type
    No. of
    Flutes
    Pilot
    Lg.
    Mfr.
    Each
    No. 0
    		0.110"2 1/2"Round20.110"Republic Drill2909A22000000
    No. 1
    		0.133"2 1/2"Round20.170"Republic Drill2909A2300000
    No. 2
    		0.155"2 1/2"Round20.120"Republic Drill2909A1300000
    No. 3
    		0.176"2 1/2"Round20.120"Republic Drill2909A1400000
    No. 4
    		0.198"2 5/8"Round20.170"Republic Drill2909A1500000
    No. 5
    		0.220"2 5/8"Round20.220"Republic Drill2909A1600000
    No. 6
    		0.241"2 5/8"Round20.230"Republic Drill2909A1700000
    No. 8
    		0.285"2 3/4"Round20.120"Republic Drill2909A1800000
    No. 10
    		0.328"2 7/8"Round20.190"Republic Drill2909A1900000
    No. 12
    		0.372"3"Round20.250"Republic Drill2909A2100000
     

    Fast-Cutting Smooth-Finish Drill-Bit Counterbores for Wood

    Image of Product. Front orientation. ZoomedIn view. Counterbores. Fast-Cutting Smooth-Finish Drill-Bit Counterbores for Wood.
    With thin cutting edges to minimize contact with the hole, these counterbores make smooth, accurate cuts at high speeds. Attach them to any drill bit with a 1/2" shank and a cutting diameter of 1/2" or larger. They move up and down the drill bit and lock into place with set screws to match the length of the screw you're installing.
    Carbon SteelAbout Carbon Steel
    Uncoated
    Body
    Dia.
    Overall
    Lg.
    For Shank
    Dia.
    For Min. Drill
    Bit Cutting Dia.
    Mfr.
    Each
    1 1/8"1"1/2"1/2"Stern2921A12000000
    1 1/4"1"1/2"1/2"Stern2921A1300000
    1 3/8"1"1/2"1/2"Stern2921A1400000
    1 1/2"1"1/2"1/2"Stern2921A1500000
    1 3/4"1"1/2"1/2"Stern2921A17000000
    2"1 1/4"1/2"1/2"Stern2921A19000000
    2 1/2"1 1/4"1/2"1/2"Stern2921A24000000
     

    Oversized Counterbores

    Designed to give screw heads a slightly loose fit, these counterbores are a bit wider than standard sizes. The extra clearance prevents binding and leaves room for a seal or O-ring around the screw head.
    High-Speed SteelAbout High-Speed Steel
    Image of Product. Front orientation. ZoomedIn view. Counterbores. Oversized Counterbores.
    Durable and wear resistant, these counterbores make accurate cuts in most materials without chipping or cracking.
    Titanium Nitride (TiN) Coated—Withstand heat, corrosion, and abrasion for longer than uncoated counterbores, so the cutting edges stay sharper.
    Pilot
    Shank
    Uncoated
    Titanium Nitride
    (TiN) Coated
    For Screw
    Size
    Body
    Dia.
    Dia.
    Lg.
    Overall
    Lg.
    Dia.
    Type
    No. of
    Flutes
    Mfr.
    Each
    Each
    1/64" Oversize
    No. 4
    		0.206"0.128"0.156"3 7/8"5/32"Round4Alvord-Polk Tool2919A5100000028225A51000000
    No. 5
    		0.221"0.141"0.188"4 1/8"3/16"Round4Alvord-Polk Tool2919A520000028225A5200000
    No. 6
    		0.244"0.154"0.219"4 5/8"7/32"Round4Alvord-Polk Tool2919A530000028225A5300000
    No. 8
    		0.288"0.18"0.250"5"1/4"Round4Alvord-Polk Tool2919A540000028225A5400000
    No. 10
    		0.330"0.206"0.281"5 1/4"9/32"Round4Alvord-Polk Tool2919A550000028225A5500000
    1/4"
    		0.398"0.266"0.313"5 5/8"5/16"Round4Alvord-Polk Tool2919A560000028225A5600000
    5/16"
    		0.491"0.328"0.375"6 1/8"3/8"Round4Alvord-Polk Tool2919A570000028225A5700000
    3/8"
    		0.588"0.391"0.500"6 1/2"1/2"Round4Alvord-Polk Tool2919A580000028225A5800000
    7/16"
    		0.679"0.453"0.500"7"1/2"Round4Alvord-Polk Tool2919A590000028225A59000000
    1/2"
    		0.773"0.515"0.500"7 1/2"1/2"Round4Alvord-Polk Tool2919A610000028225A61000000
    5/8"
    		0.961"0.641"0.625"7 5/8"5/8"Round4Alvord-Polk Tool2919A6200000028225A62000000
    3/4"
    		1.149"0.766"0.750"7 3/4"3/4"Round4Alvord-Polk Tool2919A6300000028225A63000000
    7/8"
    		1.338"0.891"0.875"8 1/8"7/8"Round4Alvord-Polk Tool2919A67000000———0
    1"
    		1.526"1.016"1.000"8 1/2"1"Round4Alvord-Polk Tool2919A65000000———0
     
    1/32" Oversize
    No. 4
    		0.221"0.143"0.156"3 7/8"5/32"Round4Alvord-Polk Tool2919A710000028225A7100000
    No. 5
    		0.236"0.156"0.188"4 1/8"3/16"Round4Alvord-Polk Tool2919A720000028225A7200000
    No. 6
    		0.259"0.169"0.219"4 5/8"7/32"Round4Alvord-Polk Tool2919A730000028225A7300000
    No. 8
    		0.303"0.195"0.250"5"1/4"Round4Alvord-Polk Tool2919A740000028225A7400000
    No. 10
    		0.345"0.221"0.281"5 1/4"9/32"Round4Alvord-Polk Tool2919A750000028225A7500000
    1/4"
    		0.413"0.281"0.313"5 5/8"5/16"Round4Alvord-Polk Tool2919A760000028225A7600000
    5/16"
    		0.506"0.344"0.375"6 1/8"3/8"Round4Alvord-Polk Tool2919A770000028225A7700000
    3/8"
    		0.603"0.406"0.500"6 1/2"1/2"Round4Alvord-Polk Tool2919A780000028225A7800000
    7/16"
    		0.694"0.469"0.500"7"1/2"Round4Alvord-Polk Tool2919A790000028225A79000000
    1/2"
    		0.788"0.531"0.500"7 1/2"1/2"Round4Alvord-Polk Tool2919A810000028225A81000000
    5/8"
    		0.976"0.656"0.625"7 5/8"5/8"Round4Alvord-Polk Tool2919A8200000028225A82000000
    3/4"
    		1.164"0.781"0.750"7 3/4"3/4"Round4Alvord-Polk Tool2919A8300000028225A83000000
    7/8"
    		1.353"0.906"0.875"8 1/8"7/8"Round4Alvord-Polk Tool2919A87000000———0
    1"
    		1.541"1.031"1.000"8 1/2"1"Round4Alvord-Polk Tool2919A85000000———0
     
    0.5 mm Oversize
    M3
    		6.0 mm3.5 mm0.219"4 1/2"3/16"Round4Alvord-Polk Tool2740A110000028225A9100000
    M4
    		7.5 mm4.5 mm0.250"5"1/4"Round4Alvord-Polk Tool2740A120000028225A9200000
    M5
    		9.0 mm5.5 mm0.281"5 5/8"5/16"Round4Alvord-Polk Tool2740A130000028225A9300000
    M6
    		10.5 mm6.5 mm0.313"5 5/8"5/16"Round4Alvord-Polk Tool2740A140000028225A9400000
    M8
    		13.5 mm8.5 mm0.375"6 1/2"1/2"Round4Alvord-Polk Tool2740A150000028225A9500000
    M10
    		16.5 mm10.5 mm0.500"7"1/2"Round4Alvord-Polk Tool2740A160000028225A96000000
    M12
    		18.5 mm12.5 mm0.500"7 1/8"1/2"Round4Alvord-Polk Tool2740A170000028225A97000000
    M14
    		21.5 mm14.5 mm0.563"7 1/2"5/8"Round4Alvord-Polk Tool2740A18000000———0
    M16
    		24.5 mm16.5 mm0.625"7 5/8"5/8"Round4Alvord-Polk Tool2740A22000000———0
    M20
    		30.5 mm20.5 mm0.750"8 1/8"7/8"Round4Alvord-Polk Tool2740A26000000———0
     
    Carbide-Tipped Steel
    Image of Product. Front orientation. ZoomedIn view. Counterbores. Oversized Counterbores.
    The hardest and most wear-resistant counterbores we offer. These bits stay sharper at higher temperatures and faster speeds for the best performance on hard and abrasive materials.
    Pilot
    Shank
    Uncoated
    For Screw
    Size
    Body
    Dia.
    Dia.
    Lg.
    Overall
    Lg.
    Dia.
    Type
    No. of
    Flutes
    Mfr.
    Each
    1/64" Oversize
    1/4"
    		0.398"17/64"0.313"5 5/8"5/16"Round3Rock River Tool3218A1130000000
    5/16"
    		0.491"21/64"0.375"6 1/8"3/8"Round3Rock River Tool3218A123000000
    3/8"
    		0.588"25/64"0.500"6 1/2"1/2"Round3Rock River Tool3218A133000000
    7/16"
    		0.679"29/64"0.500"7"1/2"Round3Rock River Tool3218A143000000
    1/2"
    		0.773"33/64"0.500"7 1/2"1/2"Round3Rock River Tool3218A153000000
    5/8"
    		0.961"41/64"0.625"7 5/8"5/8"Round3Rock River Tool3218A163000000
    3/4"
    		1.149"49/64"0.750"7 3/4"3/4"Round3Rock River Tool3218A173000000
    7/8"
    		1.338"57/64"0.875"8 1/8"7/8"Round4Rock River Tool3218A183000000
    1"
    		1.526"1 1/64"1.000"8 1/2"1"Round4Rock River Tool3218A193000000
     
    1/32" Oversize
    1/4"
    		0.413"9/32"0.313"5 5/8"5/16"Round3Rock River Tool3218A112000000
    5/16"
    		0.506"11/32"0.375"6 1/8"3/8"Round3Rock River Tool3218A122000000
    3/8"
    		0.603"13/32"0.500"6 1/2"1/2"Round3Rock River Tool3218A132000000
    7/16"
    		0.694"15/32"0.500"7"1/2"Round3Rock River Tool3218A142000000
    1/2"
    		0.788"17/32"0.500"7 1/2"1/2"Round3Rock River Tool3218A152000000
    5/8"
    		0.976"21/32"0.625"7 5/8"5/8"Round3Rock River Tool3218A162000000
    3/4"
    		1.164"25/32"0.750"7 3/4"3/4"Round3Rock River Tool3218A172000000
    7/8"
    		1.353"29/32"0.875"8 1/8"7/8"Round4Rock River Tool3218A182000000
    1"
    		1.541"1 1/32"1.000"8 1/2"1"Round4Rock River Tool3218A192000000
     

    Port Counterbores

    Cut precise port holes for hydraulic fittings. These counterbores meet aerospace, military, or international specifications for leakproof port holes, so fittings stay sealed over time, even during sudden pressure and vibration. A pilot guides the counterbore as it finishes the hole to the exact size you need for your fitting.
    You’ll need a step drill bit (sold separately) to rough out a hole with the right shape for your counterbore to finish. To complete your hole with threads, add a thread mill (sold separately).
    Carbide-Tipped Steel
    Image of Product. Front orientation. Counterbores. Port Counterbores.
    The hardest and most wear-resistant counterbores we offer. They stay sharp at high temperatures and fast speeds to machine port holes with ease in aluminum, steel, and other metals.
    Aluminum Titanium Nitride (AlTiN) Coated—The coating keeps these counterbores cool while cutting to extend their life. They're best for hard and abrasive materials, such as stainless steel and titanium.
    Counterbores
    Step Drill Bits
    Thread Mills
    Shank
    Uncoated
    Aluminum Titanium
    Nitride (AlTiN) Coated
    For Thread
    Size
    For Port
    Dash Size
    Overall
    Lg.
    Dia.
    Lg.
    Type
    No. of
    Flutes
    Pilot
    Lg.
    Mil.
    Spec.
    Mfr.
    Each
    Each
    Each
    Each
    SAE J1926/1
    5/16"-24
    		023"1/2"1 3/4"Round30.511"MS16142Scientific Cutting Tools9869N1700000009910N1100000009851N1100000005277N240000000
    3/8"-24
    		033"1/2"1 3/4"Round30.519"MS16142Scientific Cutting Tools9869N180000009910N120000009851N120000005277N25000000
    7/16"-20
    		043 1/8"1/2"1 7/8"Round30.603"MS16142Scientific Cutting Tools9869N190000009910N130000009851N130000005277N26000000
    1/2"-20
    		053 1/8"1/2"1 7/8"Round30.603"MS16142Scientific Cutting Tools9869N210000009910N140000009851N140000005277N27000000
    9/16"-18
    		063 3/8"1/2"1 7/8"Round30.675"MS16142Scientific Cutting Tools9869N220000009910N150000009851N150000005277N28000000
    3/4"-16
    		083 11/16"3/4"2 1/8"Round30.769"MS16142Scientific Cutting Tools9869N230000009910N160000009851N160000005277N29000000
    7/8"-14
    		103 13/16"3/4"2 1/8"Round30.872"MS16142Scientific Cutting Tools9869N24000000———0———05277N31000000
    1 1/16"-12
    		123 15/16"3/4"2 1/8"Round30.997"MS16142Scientific Cutting Tools9869N25000000———0———05277N32000000
    1 3/16"-12
    		144 7/32"1"2 1/4"Round31.007"MS16142Scientific Cutting Tools9869N26000000———0———05277N32000000
    1 5/16"-12
    		164 1/4"1"2 1/4"Round31.007"MS16142Scientific Cutting Tools9869N27000000———0———05277N32000000
     
    SAE AS5202
    5/16"-24
    		023"1/2"1 3/4"Round30.629"MS33649Scientific Cutting Tools9869N280000009910N170000009851N210000005277N24000000
    3/8"-24
    		033"1/2"1 3/4"Round30.643"MS33649Scientific Cutting Tools9869N290000009910N180000009851N220000005277N25000000
    7/16"-20
    		043 1/8"1/2"1 7/8"Round30.716"MS33649Scientific Cutting Tools9869N310000009910N190000009851N230000005277N26000000
    1/2"-20
    		053 1/8"1/2"1 7/8"Round30.721"MS33649Scientific Cutting Tools9869N320000009910N210000009851N240000005277N27000000
    9/16"-18
    		063 3/8"1/2"1 7/8"Round30.789"MS33649Scientific Cutting Tools9869N330000009910N220000009851N250000005277N28000000
    5/8"-18
    		073 3/8"1/2"1 7/8"Round30.805"MS33649Scientific Cutting Tools9869N340000009910N23000000———05277N28000000
    3/4"-16
    		083 27/32"3/4"2 1/8"Round30.924"MS33649Scientific Cutting Tools9869N350000009910N240000009851N260000005277N29000000
    13/16"-16
    		093 27/32"3/4"2 1/8"Round30.940"MS33649Scientific Cutting Tools9869N36000000———0———05277N29000000
    7/8"-14
    		103 15/16"3/4"2 1/8"Round31.030"MS33649Scientific Cutting Tools9869N37000000———0———05277N31000000
    1"-12
    		114 1/8"3/4"2 1/8"Round31.164"MS33649Scientific Cutting Tools9869N38000000———0———05277N32000000
    1 1/16"-12
    		124 1/8"3/4"2 1/8"Round31.164"MS33649Scientific Cutting Tools9869N39000000———0———05277N32000000
    1 3/16"-12
    		144 3/8"1"2 1/4"Round31.174"MS33649Scientific Cutting Tools9869N41000000———0———05277N32000000
    1 5/16"-12
    		164 3/8"1"2 1/4"Round31.174"MS33649Scientific Cutting Tools9869N42000000———0———05277N32000000
     
    ISO 6149-1
    M8 × 1 mm—3"1/2"1 3/4"Round30.489"—Scientific Cutting Tools9869N16000000———0———05277N22000000
    M10 × 1 mm—3"1/2"1 3/4"Round30.502"—Scientific Cutting Tools9869N11000000———0———05277N22000000
    M12 × 1.5 mm—3 1/8"1/2"1 7/8"Round30.600"—Scientific Cutting Tools9869N12000000———0———05277N33000000
    M14 × 1.5 mm—3 3/8"1/2"1 7/8"Round40.610"—Scientific Cutting Tools9869N13000000———0———05277N33000000
    M16 × 1.5 mm—3 3/8"1/2"1 7/8"Round40.674"—Scientific Cutting Tools9869N14000000———0———05277N33000000
    M18 × 1.5 mm—3 11/16"3/4"2 1/8"Round40.743"—Scientific Cutting Tools9869N15000000———0———05277N33000000
     

    Reverse Counterbores

    If the hole is obstructed, these counterbores drill from the reverse side instead. They're handy for adding counterbores to existing installations.
    After drilling your through hole, put the shank (sold separately) in your drill chuck and insert it all the way through. Then reach into the confined space to stick the counterbore head onto the shank. Pull back on the drill to counterbore the hole.
    High-Speed SteelAbout High-Speed Steel
    Image of ProductInUse. Front orientation. Contains Annotated, Border. Counterbores. Reverse Counterbores.
    Image of Product. Counterbore Head. Front orientation. Contains Annotated. Counterbores. Reverse Counterbores.

    Counterbore Head

    Durable and wear resistant, these counterbores make accurate cuts in most materials without chipping or cracking.
    Counterbores
    Required Shanks
    Uncoated
    Body
    Dia.
    Overall
    Lg.
    No. of
    Flutes
    Mfr.
    Each
    Shank
    Dia.
    Overall
    Lg.
    Each
    5/16"1/2"4Craig Tools3323A210000003/32"6"3309A3100000
    5/16"1/2"4Craig Tools3323A22000001/8"6"3309A320000
    5/16"1/2"4Craig Tools3323A23000005/32"6"3309A330000
    3/8"1/2"4Craig Tools3323A24000001/8"6"3309A320000
    3/8"1/2"4Craig Tools3323A25000005/32"6"3309A330000
    3/8"1/2"4Craig Tools3323A26000003/16"6"3309A3400000
    1/2"1/2"4Craig Tools3323A27000005/32"6"3309A330000
    1/2"1/2"4Craig Tools3323A28000003/16"6"3309A3400000
    1/2"1/2"4Craig Tools3323A29000001/4"6"3309A3500000
     

    Built-in-Pilot Counterbore Sets

    Image of Product. Front orientation. Counterbores. Built-in-Pilot Counterbore Sets.
    Create flat, close-fitting recesses for a range of screw-head sizes. The pilot centers and stabilizes the counterbore for an accurate cut and even surface on the first try.
    High-Speed Steel—Durable and wear resistant, these counterbores make accurate cuts in most materials without chipping or cracking.
    For Screw Size
    Shank
    Type
    No. of
    Flutes
    No. of
    Pieces
    Mfr.
    Each
    Uncoated High-Speed Steel
    No. 4, No. 5, No. 6, No. 8, No. 10, 1/4", 5/16", 3/8", 7/16", 1/2"
    		Round410Alvord-Polk Tool2919A120000000
     

    Changeable-Pilot Counterbore Sets

    Image of Product. Front orientation. Counterbores. Changeable-Pilot Counterbore Sets.
    A handful of counterbores and changeable pilots give you the versatility of dozens of normal counterbores. For each hole, mix and match counterbores and pilots to correspond with your screw-head and screw-shank diameter.
    High-Speed Steel—Durable and wear resistant, these counterbores make accurate cuts in most materials without chipping or cracking.
    Body Dia.
    Shank
    Type
    No. of
    Pieces
    Includes
    Container
    Type
    Mfr.
    Each
    Uncoated High-Speed Steel
    1/4", 5/16", 3/8", 7/16", 1/2"Round510 PilotsWood CaseF&D Tool2817A710000000
     

    Oversized Counterbore Sets

    Image of Product. Front orientation. Counterbores. Oversized Counterbore Sets.
    Designed to give screw heads a slightly loose fit, these counterbores are a bit wider than standard sizes. The extra clearance prevents binding and leaves room for a seal or O-ring around the screw head.
    High-Speed Steel—Durable and wear resistant, these counterbores make accurate cuts in most materials without chipping or cracking.
    For Screw Size
    Oversize
    Amount
    Shank
    Type
    No. of
    Flutes
    No. of
    Pieces
    Mfr.
    Each
    Uncoated High-Speed Steel
    No. 4, No. 5, No. 6, No. 8, No. 10, 1/4", 5/16", 3/8", 7/16", 1/2"
    		1/64"Round410Alvord-Polk Tool2919A140000000
    No. 4, No. 5, No. 6, No. 8, No. 10, 1/4", 5/16", 3/8", 7/16", 1/2"
    		1/32"Round410Alvord-Polk Tool2919A16000000
    M3, M4, M5, M6, M8, M10, M12, M14
    		0.5 mmRound48Alvord-Polk Tool2740A19000000
     

    Carbide-Insert Port Counterbore Kits

    Image of Product. Front orientation. Counterbores. Carbide-Insert Port Counterbore Kits.
    Replace dull edges instead of buying new counterbores to reduce costs during high-volume jobs. These kits come with all you need to cut precise port holes for hydraulic fittings, including a holder and two types of replaceable inserts. The pilot insert guides the counterbore as it penetrates material, and the form inserts finish the hole to the exact size you need. Secure the inserts with the included screws so they stay in place, even at the high speeds of your CNC machine. These kits meet aerospace and military specifications for leakproof port holes, so fittings stay sealed over time, even during sudden pressure and vibration. When you need to cut threads in the hole, use the included thread mill.
    Replacement inserts come factory sealed from the manufacturer for maximum traceability. The replacement form insert screw for 9816N12 can also be used to secure the pilot insert.
    Counterbores
    Replacement
    Pilot Inserts
    Replacement
    Form Inserts
    Replacement Pilot
    Insert Screws
    Thread Mills
    Shank
    For Thread
    Size
    For Port
    Dash Size
    Overall
    Lg.
    Dia.
    Lg.
    No. of
    Flutes
    Mil.
    Spec.
    Includes
    Mfr.
    Each
    Pkg.
    Qty.
    Pkg.
    Pkg.
    Qty.
    Pkg.
    Each
    Each
    SAE J1926/1
    7/16"-20
    		043 13/32"5/8"1 7/8"2MS16142One Insert Holder (Steel)
    Two Pilot Inserts (High-Speed Steel)
    Two Form Inserts (Carbide)
    One 7/16"-20 Thread Mill for Internal Threads (Carbide)
    One IP7 Torx Plus Key
    One IP8 Torx Plus Key    		Allied Machine & Engineering9816N11000000029816N17000000029816N2400000009816N31000005277N260000000
    9/16"-18
    		063 13/16"3/4"1 31/32"2MS16142One Insert Holder (Steel)
    Two Pilot Inserts (High-Speed Steel)
    Two Form Inserts (Carbide)
    One 9/16"-18 Thread Mill for Internal Threads (Carbide)
    One IP8 Torx Plus Key    		Allied Machine & Engineering9816N1200000029816N1800000029816N250000009816N3200005277N28000000
    3/4"-16
    		083 15/16"3/4"1 31/32"2MS16142One Insert Holder (Steel)
    Two Pilot Inserts (High-Speed Steel)
    Two Form Inserts (Carbide)
    One 3/4"-16 Thread Mill for Internal Threads (Carbide)
    One IP8 Torx Plus Key    		Allied Machine & Engineering9816N1300000029816N1900000029816N260000009816N3300005277N29000000
     
    SAE AS5202
    7/16"-20
    		043 17/32"5/8"1 7/8"2MS33649One Insert Holder (Steel)
    Two Pilot Inserts (High-Speed Steel)
    Two Form Inserts (Carbide)
    One 7/16"-20 Thread Mill for Internal Threads (Carbide)
    One IP7 Torx Plus Key
    One IP8 Torx Plus Key    		Allied Machine & Engineering9816N1400000029816N2100000029816N270000009816N3100005277N26000000
    9/16"-18
    		063 29/32"3/4"1 31/32"2MS33649One Insert Holder (Steel)
    Two Pilot Inserts (High-Speed Steel)
    Two Form Inserts (Carbide)
    One 9/16"-18 Thread Mill for Internal Threads (Carbide)
    One IP7 Torx Plus Key
    One IP8 Torx Plus Key    		Allied Machine & Engineering9816N1500000029816N2200000029816N280000009816N3400005277N28000000
    3/4"-16
    		084 3/32"3/4"1 31/32"2MS33649One Insert Holder (Steel)
    Two Pilot Inserts (High-Speed Steel)
    Two Form Inserts (Carbide)
    One 3/4"-16 Thread Mill for Internal Threads (Carbide)
    One IP8 Torx Plus Key    		Allied Machine & Engineering9816N1600000029816N2300000029816N290000009816N3300005277N29000000
     

    Port Counterbore Kits

    Image of Product. Front orientation. Contains Annotated. Counterbores. Port Counterbore Kits.
    All you need to machine precise port holes for hydraulic fittings, including a drill bit, port counterbore, and thread mill. These tools meet aerospace and military specifications for leakproof port holes, so fittings stay sealed over time, even during sudden pressure and vibration. With multiple cutting edges, the drill bit roughs out a hole with the right shape for the counterbore to finish. A built-in channel delivers coolant to the cutting surface to reduce heat and flush out chips more efficiently than a standard drill bit can. The counterbore has a pilot that guides the tool as it finishes the hole to the exact size you need for your fitting. Use the thread mill to cut internal threads. The mill leaves enough space in the hole for chips—or even a broken mill—to fall without damaging the workpiece.
    All tools are coated with aluminum titanium nitride (AlTiN) to reduce heat as you cut and extend tool life. While they’re most often used to make holes in aluminum and steel, you can also use them on hard metals like stainless steel.
    Counterbores
    Step Drill Bits
    Port
    Counterbores
    Thread Mills
    Thread
    Size
    For Port
    Dash Size
    Finish
    Includes
    Mil.
    Spec.
    Mfr.
    Each
    Each
    Each
    Each
    SAE J1926/1
    5/16"-24
    		02Aluminum Titanium Nitride (AlTiN) CoatedOne Step Drill Bit with Coolant Hole (Carbide)
    One Port Counterbore with Built-In Pilot (Carbide-Tipped Steel)
    One Thread Mill for Internal Threads (Carbide)    		MS16142Scientific Cutting Tools9855N1100000009851N1100000009910N1100000005277N240000000
    3/8"-24
    		03Aluminum Titanium Nitride (AlTiN) CoatedOne Step Drill Bit with Coolant Hole (Carbide)
    One Port Counterbore with Built-In Pilot (Carbide-Tipped Steel)
    One Thread Mill for Internal Threads (Carbide)    		MS16142Scientific Cutting Tools9855N120000009851N120000009910N120000005277N25000000
    7/16"-20
    		04Aluminum Titanium Nitride (AlTiN) CoatedOne Step Drill Bit with Coolant Hole (Carbide)
    One Port Counterbore with Built-In Pilot (Carbide-Tipped Steel)
    One Thread Mill for Internal Threads (Carbide)    		MS16142Scientific Cutting Tools9855N130000009851N130000009910N130000005277N26000000
    1/2"-20
    		05Aluminum Titanium Nitride (AlTiN) CoatedOne Step Drill Bit with Coolant Hole (Carbide)
    One Port Counterbore with Built-In Pilot (Carbide-Tipped Steel)
    One Thread Mill for Internal Threads (Carbide)    		MS16142Scientific Cutting Tools9855N140000009851N140000009910N140000005277N27000000
    9/16"-18
    		06Aluminum Titanium Nitride (AlTiN) CoatedOne Step Drill Bit with Coolant Hole (Carbide)
    One Port Counterbore with Built-In Pilot (Carbide-Tipped Steel)
    One Thread Mill for Internal Threads (Carbide)    		MS16142Scientific Cutting Tools9855N150000009851N150000009910N150000005277N28000000
    3/4"-16
    		08Aluminum Titanium Nitride (AlTiN) CoatedOne Step Drill Bit with Coolant Hole (Carbide)
    One Port Counterbore with Built-In Pilot (Carbide-Tipped Steel)
    One Thread Mill for Internal Threads (Carbide)    		MS16142Scientific Cutting Tools9855N160000009851N160000009910N160000005277N29000000
     
    SAE AS5202
    5/16"-24
    		02Aluminum Titanium Nitride (AlTiN) CoatedOne Step Drill Bit with Coolant Hole (Carbide)
    One Port Counterbore with Built-In Pilot (Carbide-Tipped Steel)
    One Thread Mill for Internal Threads (Carbide)    		MS33649Scientific Cutting Tools9855N170000009851N210000009910N170000005277N24000000
    3/8"-24
    		03Aluminum Titanium Nitride (AlTiN) CoatedOne Step Drill Bit with Coolant Hole (Carbide)
    One Port Counterbore with Built-In Pilot (Carbide-Tipped Steel)
    One Thread Mill for Internal Threads (Carbide)    		MS33649Scientific Cutting Tools9855N180000009851N220000009910N180000005277N25000000
    7/16"-20
    		04Aluminum Titanium Nitride (AlTiN) CoatedOne Step Drill Bit with Coolant Hole (Carbide)
    One Port Counterbore with Built-In Pilot (Carbide-Tipped Steel)
    One Thread Mill for Internal Threads (Carbide)    		MS33649Scientific Cutting Tools9855N190000009851N230000009910N190000005277N26000000
    1/2"-20
    		05Aluminum Titanium Nitride (AlTiN) CoatedOne Step Drill Bit with Coolant Hole (Carbide)
    One Port Counterbore with Built-In Pilot (Carbide-Tipped Steel)
    One Thread Mill for Internal Threads (Carbide)    		MS33649Scientific Cutting Tools9855N210000009851N240000009910N210000005277N27000000
    9/16"-18
    		06Aluminum Titanium Nitride (AlTiN) CoatedOne Step Drill Bit with Coolant Hole (Carbide)
    One Port Counterbore with Built-In Pilot (Carbide-Tipped Steel)
    One Thread Mill for Internal Threads (Carbide)    		MS33649Scientific Cutting Tools9855N220000009851N250000009910N220000005277N28000000
    3/4"-16
    		08Aluminum Titanium Nitride (AlTiN) CoatedOne Step Drill Bit with Coolant Hole (Carbide)
    One Port Counterbore with Built-In Pilot (Carbide-Tipped Steel)
    One Thread Mill for Internal Threads (Carbide)    		MS33649Scientific Cutting Tools9855N230000009851N260000009910N240000005277N29000000
     
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