McMaster-Carr logo
    Forward
    Enter e-mail addresses in the fields below
    Message
    Cancel
    Print
    How can we improve?
    Comments
    E-mail address (if you would like a response)
    18 Products
    About Counterbores
    industrial info icon

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

    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
    No. of
    Pieces
    Shank
    Type
    No. of
    Flutes
    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"
    		10Round400000000000000
     

    Built-In-Pilot Counterbores

    The pilot centers the counterbore and prevents wobbling for an accurate cut on the first try. With dimensions that match standard screw-head diameters and thread diameters, this is your plug-and-play option for pilot-driven counterbores.
    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
    Each
    Each
    No. 10
    		0.314"0.19"0.281"5 1/4"9/32"Round4000000000000000000000000000
     

    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
    No. of
    Pieces
    Shank
    Type
    No. of
    Flutes
    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"
    		9Round2Plastic Case000000000000000
    No. 5, No. 6, No. 8, No. 10, 1/4", 5/16", 3/8", 7/16", 1/2"
    		9Round2Plastic Case00000000000000
     

    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 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
    Each
    Each
     
    1/64" Oversize
    No. 10
    		0.330"0.206"0.281"5 1/4"9/32"Round4000000000000000000000000000
     
    1/32" Oversize
    No. 10
    		0.345"0.221"0.281"5 1/4"9/32"Round40000000000000000000000000
     

    Counterbores for High-Profile Rounded-Head Screws

    Image of Product. Front orientation. Counterbores. 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 Steel
    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.
    Each
    No. 10
    		0.328"2 7/8"Round20.190"0000000000000
     

    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 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.
    Overall
    Lg.
    Dia.
    Type
    No. of
    Flutes
    Max. Hole
    Drilling Dp.
    Each
    No. 10
    		0.332"1 1/2"5/16"Round20.312"00000000000000
    No. 10
    		0.332"2 1/4"3/8"Round20.6"00000000000000
     

    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
    No. of
    Pieces
    Oversize
    Amount
    Shank
    Type
    No. of
    Flutes
    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"
    		101/64"Round400000000000000
    No. 4, No. 5, No. 6, No. 8, No. 10, 1/4", 5/16", 3/8", 7/16", 1/2"
    		101/32"Round40000000000000
     

    Long-Life Counterbore Drill Bits

    Image of Product. Front orientation. Contains Annotated. Counterbore Drill Bits. Long-Life Counterbore Drill Bits.
    Also known as subland drill bits, these last longer than standard counterbore drill bits because the diameter stays the same after sharpening. They drill and counterbore at the same time. After drilling and counterboring, tap the hole and install your fastener.
    Dia.
    Lg.
    For Screw
    Size
    Body
    Step
    Step
    Overall
    No. of
    Flutes
    Point
    Angle
    For Use On
    Each
    Uncoated High-Speed Steel
    No. 10
    		0.313"0.190"1/2"2 13/16"2118°Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel00000000000000
     

    Oversized Long-Life Counterbore Drill Bits

    Image of Product. Front orientation. Contains Annotated. Counterbore Drill Bits. Oversized Long-Life Counterbore Drill Bits.
    These counterbores are often used when screw holes in sheets or layers are misaligned. Also known as subland drill bits, they last longer than standard counterbore drill bits because the diameter stays the same after sharpening. They drill and counterbore at the same time. After drilling and counterboring, tap the hole and install your fastener. The diameters account for the 1/32” or 1/64” oversized diameter rating.
    Dia.
    Lg.
    For Screw
    Size
    Body
    Step
    Step
    Overall
    No. of
    Flutes
    Point
    Angle
    For Use On
    Each
    Uncoated High-Speed Steel
     
    1/64" Oversize
    No. 10
    		0.328"0.206"5/8"4 5/8"2118°Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel00000000000000
    No. 10
    		0.344"0.206"1/2"4 3/4"2118°Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel0000000000000
     

    Counterbore Drill Bits

    Image of Product. Front orientation. Contains Annotated. Counterbore Drill Bits. Counterbore Drill Bits.
    Often called step drill bits, these drill and counterbore holes at the same time. After drilling and counterboring, tap the hole and install your fastener. The body diameter may decrease after multiple sharpenings.
    Dia.
    Lg.
    For Screw
    Size
    Body
    Step
    Step
    Overall
    Point
    Angle
    For Use On
    Each
    Uncoated High-Speed Steel
    No. 10
    		0.332"0.204"5/8"4 3/4"118°Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel0000000000000
     
    back to top