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    12 Products
    About Counterbores
    industrial info icon

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

    Material

    Size Designation

    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 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
    7/8"
    		1.322"7/8"0.875"8 1/8"7/8"Round4Alvord-Polk Tool2919A47000000028225A440000000
     
    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.
    C2 Carbide—Hard enough to cut cleanly through cast iron and nonferrous metals.
    C5 Carbide—Harder than C2 Carbide, these counterbores cut steel without damaging themselves or the hole.
    Pilot
    Shank
    Uncoated
    For Screw
    Size
    Body
    Dia.
    Dia.
    Lg.
    Overall
    Lg.
    Dia.
    Type
    No. of
    Flutes
    Mfr.
    Each
    C2 Carbide
    7/8"
    		1.322"7/8"0.875"8 1/8"7/8"Round4Rock River Tool3218A1810000000
     
    C5 Carbide
    7/8"
    		1.322"7/8"0.875"8 1/8"7/8"Round4Rock River Tool3218A281000000
     

    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
    7/8"
    		1.338"0.891"0.875"8 1/8"7/8"Round4Alvord-Polk Tool2919A67000000028225A640000000
     
    1/32" Oversize
    7/8"
    		1.353"0.906"0.875"8 1/8"7/8"Round4Alvord-Polk Tool2919A8700000028225A84000000
     
    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.
    C2 Carbide—Hard enough to cut cleanly through cast iron and nonferrous metals.
    C5 Carbide—Harder than C2 Carbide, these counterbores cut steel without damaging themselves or the hole.
    Pilot
    Shank
    Uncoated
    For Screw
    Size
    Body
    Dia.
    Dia.
    Lg.
    Overall
    Lg.
    Dia.
    Type
    No. of
    Flutes
    Mfr.
    Each
    C2 Carbide
     
    1/64" Oversize
    7/8"
    		1.338"57/64"0.875"8 1/8"7/8"Round4Rock River Tool3218A1830000000
     
    1/32" Oversize
    7/8"
    		1.353"29/32"0.875"8 1/8"7/8"Round4Rock River Tool3218A182000000
     
    C5 Carbide
     
    1/64" Oversize
    7/8"
    		1.338"57/64"0.875"8 1/8"7/8"Round4Rock River Tool3218A283000000
     
    1/32" Oversize
    7/8"
    		1.353"29/32"0.875"8 1/8"7/8"Round4Rock River Tool3218A282000000
     
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