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About Counterbores
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Create flat-bottomed holes, so your screw heads sit flush, recessed, or slightly raised.
Counterbore Type
Oversized Counterbores
High-Speed Steel
 |
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" | Round | 4 | Alvord-Polk Tool | 2919A51 | 000000 | 28225A51 | 000000 | ||
| No. 5 | 0.221" | 0.141" | 0.188" | 4 1/8" | 3/16" | Round | 4 | Alvord-Polk Tool | 2919A52 | 00000 | 28225A52 | 00000 | ||
| No. 6 | 0.244" | 0.154" | 0.219" | 4 5/8" | 7/32" | Round | 4 | Alvord-Polk Tool | 2919A53 | 00000 | 28225A53 | 00000 | ||
| No. 8 | 0.288" | 0.18" | 0.250" | 5" | 1/4" | Round | 4 | Alvord-Polk Tool | 2919A54 | 00000 | 28225A54 | 00000 | ||
| No. 10 | 0.330" | 0.206" | 0.281" | 5 1/4" | 9/32" | Round | 4 | Alvord-Polk Tool | 2919A55 | 00000 | 28225A55 | 00000 | ||
| 1/4" | 0.398" | 0.266" | 0.313" | 5 5/8" | 5/16" | Round | 4 | Alvord-Polk Tool | 2919A56 | 00000 | 28225A56 | 00000 | ||
| 5/16" | 0.491" | 0.328" | 0.375" | 6 1/8" | 3/8" | Round | 4 | Alvord-Polk Tool | 2919A57 | 00000 | 28225A57 | 00000 | ||
| 3/8" | 0.588" | 0.391" | 0.500" | 6 1/2" | 1/2" | Round | 4 | Alvord-Polk Tool | 2919A58 | 00000 | 28225A58 | 00000 | ||
| 7/16" | 0.679" | 0.453" | 0.500" | 7" | 1/2" | Round | 4 | Alvord-Polk Tool | 2919A59 | 00000 | 28225A59 | 000000 | ||
| 1/2" | 0.773" | 0.515" | 0.500" | 7 1/2" | 1/2" | Round | 4 | Alvord-Polk Tool | 2919A61 | 00000 | 28225A61 | 000000 | ||
| 5/8" | 0.961" | 0.641" | 0.625" | 7 5/8" | 5/8" | Round | 4 | Alvord-Polk Tool | 2919A62 | 000000 | 28225A62 | 000000 | ||
| 3/4" | 1.149" | 0.766" | 0.750" | 7 3/4" | 3/4" | Round | 4 | Alvord-Polk Tool | 2919A63 | 000000 | 28225A63 | 000000 | ||
| 7/8" | 1.338" | 0.891" | 0.875" | 8 1/8" | 7/8" | Round | 4 | Alvord-Polk Tool | 2919A67 | 000000 | ——— | 0 | ||
| 1" | 1.526" | 1.016" | 1.000" | 8 1/2" | 1" | Round | 4 | Alvord-Polk Tool | 2919A65 | 000000 | ——— | 0 | ||
1/32" Oversize | ||||||||||||||
| No. 4 | 0.221" | 0.143" | 0.156" | 3 7/8" | 5/32" | Round | 4 | Alvord-Polk Tool | 2919A71 | 00000 | 28225A71 | 00000 | ||
| No. 5 | 0.236" | 0.156" | 0.188" | 4 1/8" | 3/16" | Round | 4 | Alvord-Polk Tool | 2919A72 | 00000 | 28225A72 | 00000 | ||
| No. 6 | 0.259" | 0.169" | 0.219" | 4 5/8" | 7/32" | Round | 4 | Alvord-Polk Tool | 2919A73 | 00000 | 28225A73 | 00000 | ||
| No. 8 | 0.303" | 0.195" | 0.250" | 5" | 1/4" | Round | 4 | Alvord-Polk Tool | 2919A74 | 00000 | 28225A74 | 00000 | ||
| No. 10 | 0.345" | 0.221" | 0.281" | 5 1/4" | 9/32" | Round | 4 | Alvord-Polk Tool | 2919A75 | 00000 | 28225A75 | 00000 | ||
| 1/4" | 0.413" | 0.281" | 0.313" | 5 5/8" | 5/16" | Round | 4 | Alvord-Polk Tool | 2919A76 | 00000 | 28225A76 | 00000 | ||
| 5/16" | 0.506" | 0.344" | 0.375" | 6 1/8" | 3/8" | Round | 4 | Alvord-Polk Tool | 2919A77 | 00000 | 28225A77 | 00000 | ||
| 3/8" | 0.603" | 0.406" | 0.500" | 6 1/2" | 1/2" | Round | 4 | Alvord-Polk Tool | 2919A78 | 00000 | 28225A78 | 00000 | ||
| 7/16" | 0.694" | 0.469" | 0.500" | 7" | 1/2" | Round | 4 | Alvord-Polk Tool | 2919A79 | 00000 | 28225A79 | 000000 | ||
| 1/2" | 0.788" | 0.531" | 0.500" | 7 1/2" | 1/2" | Round | 4 | Alvord-Polk Tool | 2919A81 | 00000 | 28225A81 | 000000 | ||
| 5/8" | 0.976" | 0.656" | 0.625" | 7 5/8" | 5/8" | Round | 4 | Alvord-Polk Tool | 2919A82 | 000000 | 28225A82 | 000000 | ||
| 3/4" | 1.164" | 0.781" | 0.750" | 7 3/4" | 3/4" | Round | 4 | Alvord-Polk Tool | 2919A83 | 000000 | 28225A83 | 000000 | ||
| 7/8" | 1.353" | 0.906" | 0.875" | 8 1/8" | 7/8" | Round | 4 | Alvord-Polk Tool | 2919A87 | 000000 | ——— | 0 | ||
| 1" | 1.541" | 1.031" | 1.000" | 8 1/2" | 1" | Round | 4 | Alvord-Polk Tool | 2919A85 | 000000 | ——— | 0 | ||
0.5 mm Oversize | ||||||||||||||
| M3 | 6.0 mm | 3.5 mm | 0.219" | 4 1/2" | 3/16" | Round | 4 | Alvord-Polk Tool | 2740A11 | 00000 | 28225A91 | 00000 | ||
| M4 | 7.5 mm | 4.5 mm | 0.250" | 5" | 1/4" | Round | 4 | Alvord-Polk Tool | 2740A12 | 00000 | 28225A92 | 00000 | ||
| M5 | 9.0 mm | 5.5 mm | 0.281" | 5 5/8" | 5/16" | Round | 4 | Alvord-Polk Tool | 2740A13 | 00000 | 28225A93 | 00000 | ||
| M6 | 10.5 mm | 6.5 mm | 0.313" | 5 5/8" | 5/16" | Round | 4 | Alvord-Polk Tool | 2740A14 | 00000 | 28225A94 | 00000 | ||
| M8 | 13.5 mm | 8.5 mm | 0.375" | 6 1/2" | 1/2" | Round | 4 | Alvord-Polk Tool | 2740A15 | 00000 | 28225A95 | 00000 | ||
| M10 | 16.5 mm | 10.5 mm | 0.500" | 7" | 1/2" | Round | 4 | Alvord-Polk Tool | 2740A16 | 00000 | 28225A96 | 000000 | ||
| M12 | 18.5 mm | 12.5 mm | 0.500" | 7 1/8" | 1/2" | Round | 4 | Alvord-Polk Tool | 2740A17 | 00000 | 28225A97 | 000000 | ||
| M14 | 21.5 mm | 14.5 mm | 0.563" | 7 1/2" | 5/8" | Round | 4 | Alvord-Polk Tool | 2740A18 | 000000 | ——— | 0 | ||
| M16 | 24.5 mm | 16.5 mm | 0.625" | 7 5/8" | 5/8" | Round | 4 | Alvord-Polk Tool | 2740A22 | 000000 | ——— | 0 | ||
| M20 | 30.5 mm | 20.5 mm | 0.750" | 8 1/8" | 7/8" | Round | 4 | Alvord-Polk Tool | 2740A26 | 000000 | ——— | 0 | ||
Carbide-Tipped Steel
|
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" | Round | 3 | Rock River Tool | 3218A113 | 0000000 | ||
| 5/16" | 0.491" | 21/64" | 0.375" | 6 1/8" | 3/8" | Round | 3 | Rock River Tool | 3218A123 | 000000 | ||
| 3/8" | 0.588" | 25/64" | 0.500" | 6 1/2" | 1/2" | Round | 3 | Rock River Tool | 3218A133 | 000000 | ||
| 7/16" | 0.679" | 29/64" | 0.500" | 7" | 1/2" | Round | 3 | Rock River Tool | 3218A143 | 000000 | ||
| 1/2" | 0.773" | 33/64" | 0.500" | 7 1/2" | 1/2" | Round | 3 | Rock River Tool | 3218A153 | 000000 | ||
| 5/8" | 0.961" | 41/64" | 0.625" | 7 5/8" | 5/8" | Round | 3 | Rock River Tool | 3218A163 | 000000 | ||
| 3/4" | 1.149" | 49/64" | 0.750" | 7 3/4" | 3/4" | Round | 3 | Rock River Tool | 3218A173 | 000000 | ||
| 7/8" | 1.338" | 57/64" | 0.875" | 8 1/8" | 7/8" | Round | 4 | Rock River Tool | 3218A183 | 000000 | ||
| 1" | 1.526" | 1 1/64" | 1.000" | 8 1/2" | 1" | Round | 4 | Rock River Tool | 3218A193 | 000000 | ||
1/32" Oversize | ||||||||||||
| 1/4" | 0.413" | 9/32" | 0.313" | 5 5/8" | 5/16" | Round | 3 | Rock River Tool | 3218A112 | 000000 | ||
| 5/16" | 0.506" | 11/32" | 0.375" | 6 1/8" | 3/8" | Round | 3 | Rock River Tool | 3218A122 | 000000 | ||
| 3/8" | 0.603" | 13/32" | 0.500" | 6 1/2" | 1/2" | Round | 3 | Rock River Tool | 3218A132 | 000000 | ||
| 7/16" | 0.694" | 15/32" | 0.500" | 7" | 1/2" | Round | 3 | Rock River Tool | 3218A142 | 000000 | ||
| 1/2" | 0.788" | 17/32" | 0.500" | 7 1/2" | 1/2" | Round | 3 | Rock River Tool | 3218A152 | 000000 | ||
| 5/8" | 0.976" | 21/32" | 0.625" | 7 5/8" | 5/8" | Round | 3 | Rock River Tool | 3218A162 | 000000 | ||
| 3/4" | 1.164" | 25/32" | 0.750" | 7 3/4" | 3/4" | Round | 3 | Rock River Tool | 3218A172 | 000000 | ||
| 7/8" | 1.353" | 29/32" | 0.875" | 8 1/8" | 7/8" | Round | 4 | Rock River Tool | 3218A182 | 000000 | ||
| 1" | 1.541" | 1 1/32" | 1.000" | 8 1/2" | 1" | Round | 4 | Rock River Tool | 3218A192 | 000000 | ||
Built-in-Pilot Counterbores
High-Speed Steel
|
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" | Round | 4 | Alvord-Polk Tool | 2919A31 | 000000 | 28225A31 | 000000 | ||
| No. 5 | 0.205" | 1/8" | 0.188" | 4 1/8" | 3/16" | Round | 4 | Alvord-Polk Tool | 2919A32 | 00000 | 28225A32 | 00000 | ||
| No. 6 | 0.228" | 0.138" | 0.219" | 4 5/8" | 7/32" | Round | 4 | Alvord-Polk Tool | 2919A33 | 00000 | 28225A33 | 00000 | ||
| No. 8 | 0.272" | 0.164" | 0.250" | 5" | 1/4" | Round | 4 | Alvord-Polk Tool | 2919A34 | 00000 | 28225A34 | 00000 | ||
| No. 10 | 0.314" | 0.19" | 0.281" | 5 1/4" | 9/32" | Round | 4 | Alvord-Polk Tool | 2919A35 | 00000 | 28225A35 | 00000 | ||
| 1/4" | 0.382" | 1/4" | 0.313" | 5 5/8" | 5/16" | Round | 4 | Alvord-Polk Tool | 2919A36 | 00000 | 28225A36 | 00000 | ||
| 5/16" | 0.475" | 5/16" | 0.375" | 6 1/8" | 3/8" | Round | 4 | Alvord-Polk Tool | 2919A37 | 00000 | 28225A37 | 00000 | ||
| 3/8" | 0.572" | 3/8" | 0.500" | 6 1/2" | 1/2" | Round | 4 | Alvord-Polk Tool | 2919A38 | 00000 | 28225A38 | 00000 | ||
| 7/16" | 0.663" | 7/16" | 0.500" | 7" | 1/2" | Round | 4 | Alvord-Polk Tool | 2919A39 | 00000 | 28225A39 | 000000 | ||
| 1/2" | 0.757" | 1/2" | 0.500" | 7 1/2" | 1/2" | Round | 4 | Alvord-Polk Tool | 2919A41 | 00000 | 28225A41 | 000000 | ||
| 5/8" | 0.945" | 5/8" | 0.625" | 7 5/8" | 5/8" | Round | 4 | Alvord-Polk Tool | 2919A42 | 000000 | 28225A42 | 000000 | ||
| 3/4" | 1.133" | 3/4" | 0.750" | 7 3/4" | 3/4" | Round | 4 | Alvord-Polk Tool | 2919A43 | 000000 | 28225A43 | 000000 | ||
| 7/8" | 1.322" | 7/8" | 0.875" | 8 1/8" | 7/8" | Round | 4 | Alvord-Polk Tool | 2919A47 | 000000 | 28225A44 | 000000 | ||
| 1" | 1.510" | 1" | 1.000" | 8 1/2" | 1" | Round | 4 | Alvord-Polk Tool | 2919A45 | 000000 | 28225A45 | 000000 | ||
| M4 | 8.0 mm | 3.3 mm | 0.197" | 2 3/4" | 3/16" | Round | 3 | Dormer Pramet | 2919A27 | 00000 | ——— | 0 | ||
| M5 | 10.0 mm | 4.2 mm | 0.217" | 3 1/8" | 5/16" | Round | 3 | Dormer Pramet | 2919A28 | 00000 | ——— | 0 | ||
| M6 | 11.0 mm | 5.0 mm | 0.236" | 3 1/8" | 5/16" | Round | 3 | Dormer Pramet | 2919A29 | 00000 | ——— | 0 | ||
| M8 | 15.0 mm | 6.8 mm | 0.315" | 3 7/8" | 1/2" | Round | 3 | Dormer Pramet | 2919A97 | 00000 | ——— | 0 | ||
| M10 | 18.0 mm | 8.5 mm | 0.394" | 3 7/8" | 1/2" | Round | 3 | Dormer Pramet | 2919A98 | 00000 | ——— | 0 | ||
| M12 | 20.0 mm | 10.2 mm | 0.394" | 3 7/8" | 1/2" | Round | 3 | Dormer Pramet | 2919A99 | 00000 | ——— | 0 | ||
Cobalt Steel
|
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" | Round | 3 | Keo | 11162N11 | 000000 | ||
| No. 6 | 0.228" | 0.138" | 0.203" | 3" | 7/32" | Round | 3 | Keo | 11162N13 | 00000 | ||
| No. 8 | 0.272" | 0.164" | 0.250" | 3" | 1/4" | Round | 3 | Keo | 11162N14 | 00000 | ||
| No. 10 | 0.314" | 0.19" | 0.266" | 4 1/2" | 9/32" | Round | 3 | Keo | 11162N15 | 00000 | ||
| 1/4" | 0.382" | 1/4" | 0.313" | 4 1/2" | 5/16" | Round | 3 | Keo | 11162N16 | 00000 | ||
| 5/16" | 0.475" | 5/16" | 0.359" | 4 1/2" | 3/8" | Round | 3 | Keo | 11162N17 | 00000 | ||
| 3/8" | 0.572" | 3/8" | 0.500" | 5" | 1/2" | Round | 3 | Keo | 11162N18 | 00000 | ||
| 1/2" | 0.757" | 1/2" | 0.500" | 6" | 1/2" | Round | 3 | Keo | 11162N21 | 000000 | ||
Carbide-Tipped Steel
|
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" | Round | 3 | Rock River Tool | 3218A111 | 0000000 | ||
| 5/16" | 0.475" | 5/16" | 0.375" | 6 1/8" | 3/8" | Round | 3 | Rock River Tool | 3218A121 | 000000 | ||
| 3/8" | 0.572" | 3/8" | 0.500" | 6 1/2" | 1/2" | Round | 3 | Rock River Tool | 3218A131 | 000000 | ||
| 7/16" | 0.663" | 7/16" | 0.500" | 7" | 1/2" | Round | 3 | Rock River Tool | 3218A141 | 000000 | ||
| 1/2" | 0.757" | 1/2" | 0.500" | 7 1/2" | 1/2" | Round | 3 | Rock River Tool | 3218A151 | 000000 | ||
| 5/8" | 0.945" | 5/8" | 0.625" | 7 5/8" | 5/8" | Round | 3 | Rock River Tool | 3218A161 | 000000 | ||
| 3/4" | 1.133" | 3/4" | 0.750" | 7 3/4" | 3/4" | Round | 3 | Rock River Tool | 3218A171 | 000000 | ||
| 7/8" | 1.322" | 7/8" | 0.875" | 8 1/8" | 7/8" | Round | 4 | Rock River Tool | 3218A181 | 000000 | ||
| 1" | 1.510" | 1" | 1.000" | 8 1/2" | 1" | Round | 4 | Rock River Tool | 3218A191 | 000000 | ||
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" | Round | 4 | 10 | Alvord-Polk Tool | 2919A12 | 0000000 | ||
Counterbores for High-Profile Rounded-Head Screws
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. | Mfr. | Each | |||
| No. 0 | 0.110" | 2 1/2" | Round | 2 | 0.110" | Republic Drill | 2909A22 | 000000 | ||
| No. 1 | 0.133" | 2 1/2" | Round | 2 | 0.170" | Republic Drill | 2909A23 | 00000 | ||
| No. 2 | 0.155" | 2 1/2" | Round | 2 | 0.120" | Republic Drill | 2909A13 | 00000 | ||
| No. 3 | 0.176" | 2 1/2" | Round | 2 | 0.120" | Republic Drill | 2909A14 | 00000 | ||
| No. 4 | 0.198" | 2 5/8" | Round | 2 | 0.170" | Republic Drill | 2909A15 | 00000 | ||
| No. 5 | 0.220" | 2 5/8" | Round | 2 | 0.220" | Republic Drill | 2909A16 | 00000 | ||
| No. 6 | 0.241" | 2 5/8" | Round | 2 | 0.230" | Republic Drill | 2909A17 | 00000 | ||
| No. 8 | 0.285" | 2 3/4" | Round | 2 | 0.120" | Republic Drill | 2909A18 | 00000 | ||
| No. 10 | 0.328" | 2 7/8" | Round | 2 | 0.190" | Republic Drill | 2909A19 | 00000 | ||
| No. 12 | 0.372" | 3" | Round | 2 | 0.250" | Republic Drill | 2909A21 | 00000 | ||
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" | Round | 4 | 10 | Alvord-Polk Tool | 2919A14 | 0000000 | ||
| No. 4, No. 5, No. 6, No. 8, No. 10, 1/4", 5/16", 3/8", 7/16", 1/2" | 1/32" | Round | 4 | 10 | Alvord-Polk Tool | 2919A16 | 000000 | ||
| M3, M4, M5, M6, M8, M10, M12, M14 | 0.5 mm | Round | 4 | 8 | Alvord-Polk Tool | 2740A19 | 000000 | ||
Coolant-Fed Port Counterbores
Carbide-Tipped Steel
 |
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 | 04 | 3 1/2" | 1/2" | 2" | Round | 3 | 0.551" | MS16142 | Everede Tool | 9833N11 | 0000000 | 9851N13 | 0000000 | 5277N26 | 0000000 | ||
| 9/16"-18 | 06 | 3 1/2" | 1/2" | 2" | Round | 3 | 0.610" | MS16142 | Everede Tool | 9833N12 | 000000 | 9851N15 | 000000 | 5277N28 | 000000 | ||
| 3/4"-16 | 08 | 3 1/2" | 3/4" | 2" | Round | 3 | 0.689" | MS16142 | Everede Tool | 9833N13 | 000000 | 9851N16 | 000000 | 5277N29 | 000000 | ||
SAE AS5202 | |||||||||||||||||
| 7/16"-20 | 04 | 3 1/2" | 1/2" | 2" | Round | 3 | 0.661" | MS33649 | Everede Tool | 9833N14 | 000000 | 9851N23 | 000000 | 5277N26 | 000000 | ||
| 9/16"-18 | 06 | 3 1/2" | 1/2" | 2" | Round | 3 | 0.714" | MS33649 | Everede Tool | 9833N15 | 000000 | 9851N25 | 000000 | 5277N28 | 000000 | ||
| 3/4"-16 | 08 | 4" | 3/4" | 2" | Round | 3 | 0.839" | MS33649 | Everede Tool | 9833N16 | 000000 | 9851N26 | 000000 | 5277N29 | 000000 | ||
Port Counterbores
Carbide-Tipped Steel
 |
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 | 02 | 3" | 1/2" | 1 3/4" | Round | 3 | 0.511" | MS16142 | Scientific Cutting Tools | 9869N17 | 0000000 | 9910N11 | 0000000 | 9851N11 | 0000000 | 5277N24 | 0000000 | ||
| 3/8"-24 | 03 | 3" | 1/2" | 1 3/4" | Round | 3 | 0.519" | MS16142 | Scientific Cutting Tools | 9869N18 | 000000 | 9910N12 | 000000 | 9851N12 | 000000 | 5277N25 | 000000 | ||
| 7/16"-20 | 04 | 3 1/8" | 1/2" | 1 7/8" | Round | 3 | 0.603" | MS16142 | Scientific Cutting Tools | 9869N19 | 000000 | 9910N13 | 000000 | 9851N13 | 000000 | 5277N26 | 000000 | ||
| 1/2"-20 | 05 | 3 1/8" | 1/2" | 1 7/8" | Round | 3 | 0.603" | MS16142 | Scientific Cutting Tools | 9869N21 | 000000 | 9910N14 | 000000 | 9851N14 | 000000 | 5277N27 | 000000 | ||
| 9/16"-18 | 06 | 3 3/8" | 1/2" | 1 7/8" | Round | 3 | 0.675" | MS16142 | Scientific Cutting Tools | 9869N22 | 000000 | 9910N15 | 000000 | 9851N15 | 000000 | 5277N28 | 000000 | ||
| 3/4"-16 | 08 | 3 11/16" | 3/4" | 2 1/8" | Round | 3 | 0.769" | MS16142 | Scientific Cutting Tools | 9869N23 | 000000 | 9910N16 | 000000 | 9851N16 | 000000 | 5277N29 | 000000 | ||
| 7/8"-14 | 10 | 3 13/16" | 3/4" | 2 1/8" | Round | 3 | 0.872" | MS16142 | Scientific Cutting Tools | 9869N24 | 000000 | ——— | 0 | ——— | 0 | 5277N31 | 000000 | ||
| 1 1/16"-12 | 12 | 3 15/16" | 3/4" | 2 1/8" | Round | 3 | 0.997" | MS16142 | Scientific Cutting Tools | 9869N25 | 000000 | ——— | 0 | ——— | 0 | 5277N32 | 000000 | ||
| 1 3/16"-12 | 14 | 4 7/32" | 1" | 2 1/4" | Round | 3 | 1.007" | MS16142 | Scientific Cutting Tools | 9869N26 | 000000 | ——— | 0 | ——— | 0 | 5277N32 | 000000 | ||
| 1 5/16"-12 | 16 | 4 1/4" | 1" | 2 1/4" | Round | 3 | 1.007" | MS16142 | Scientific Cutting Tools | 9869N27 | 000000 | ——— | 0 | ——— | 0 | 5277N32 | 000000 | ||
SAE AS5202 | |||||||||||||||||||
| 5/16"-24 | 02 | 3" | 1/2" | 1 3/4" | Round | 3 | 0.629" | MS33649 | Scientific Cutting Tools | 9869N28 | 000000 | 9910N17 | 000000 | 9851N21 | 000000 | 5277N24 | 000000 | ||
| 3/8"-24 | 03 | 3" | 1/2" | 1 3/4" | Round | 3 | 0.643" | MS33649 | Scientific Cutting Tools | 9869N29 | 000000 | 9910N18 | 000000 | 9851N22 | 000000 | 5277N25 | 000000 | ||
| 7/16"-20 | 04 | 3 1/8" | 1/2" | 1 7/8" | Round | 3 | 0.716" | MS33649 | Scientific Cutting Tools | 9869N31 | 000000 | 9910N19 | 000000 | 9851N23 | 000000 | 5277N26 | 000000 | ||
| 1/2"-20 | 05 | 3 1/8" | 1/2" | 1 7/8" | Round | 3 | 0.721" | MS33649 | Scientific Cutting Tools | 9869N32 | 000000 | 9910N21 | 000000 | 9851N24 | 000000 | 5277N27 | 000000 | ||
| 9/16"-18 | 06 | 3 3/8" | 1/2" | 1 7/8" | Round | 3 | 0.789" | MS33649 | Scientific Cutting Tools | 9869N33 | 000000 | 9910N22 | 000000 | 9851N25 | 000000 | 5277N28 | 000000 | ||
| 5/8"-18 | 07 | 3 3/8" | 1/2" | 1 7/8" | Round | 3 | 0.805" | MS33649 | Scientific Cutting Tools | 9869N34 | 000000 | 9910N23 | 000000 | ——— | 0 | 5277N28 | 000000 | ||
| 3/4"-16 | 08 | 3 27/32" | 3/4" | 2 1/8" | Round | 3 | 0.924" | MS33649 | Scientific Cutting Tools | 9869N35 | 000000 | 9910N24 | 000000 | 9851N26 | 000000 | 5277N29 | 000000 | ||
| 13/16"-16 | 09 | 3 27/32" | 3/4" | 2 1/8" | Round | 3 | 0.940" | MS33649 | Scientific Cutting Tools | 9869N36 | 000000 | ——— | 0 | ——— | 0 | 5277N29 | 000000 | ||
| 7/8"-14 | 10 | 3 15/16" | 3/4" | 2 1/8" | Round | 3 | 1.030" | MS33649 | Scientific Cutting Tools | 9869N37 | 000000 | ——— | 0 | ——— | 0 | 5277N31 | 000000 | ||
| 1"-12 | 11 | 4 1/8" | 3/4" | 2 1/8" | Round | 3 | 1.164" | MS33649 | Scientific Cutting Tools | 9869N38 | 000000 | ——— | 0 | ——— | 0 | 5277N32 | 000000 | ||
| 1 1/16"-12 | 12 | 4 1/8" | 3/4" | 2 1/8" | Round | 3 | 1.164" | MS33649 | Scientific Cutting Tools | 9869N39 | 000000 | ——— | 0 | ——— | 0 | 5277N32 | 000000 | ||
| 1 3/16"-12 | 14 | 4 3/8" | 1" | 2 1/4" | Round | 3 | 1.174" | MS33649 | Scientific Cutting Tools | 9869N41 | 000000 | ——— | 0 | ——— | 0 | 5277N32 | 000000 | ||
| 1 5/16"-12 | 16 | 4 3/8" | 1" | 2 1/4" | Round | 3 | 1.174" | MS33649 | Scientific Cutting Tools | 9869N42 | 000000 | ——— | 0 | ——— | 0 | 5277N32 | 000000 | ||
ISO 6149-1 | |||||||||||||||||||
| M8 × 1 mm | — | 3" | 1/2" | 1 3/4" | Round | 3 | 0.489" | — | Scientific Cutting Tools | 9869N16 | 000000 | ——— | 0 | ——— | 0 | 5277N22 | 000000 | ||
| M10 × 1 mm | — | 3" | 1/2" | 1 3/4" | Round | 3 | 0.502" | — | Scientific Cutting Tools | 9869N11 | 000000 | ——— | 0 | ——— | 0 | 5277N22 | 000000 | ||
| M12 × 1.5 mm | — | 3 1/8" | 1/2" | 1 7/8" | Round | 3 | 0.600" | — | Scientific Cutting Tools | 9869N12 | 000000 | ——— | 0 | ——— | 0 | 5277N33 | 000000 | ||
| M14 × 1.5 mm | — | 3 3/8" | 1/2" | 1 7/8" | Round | 4 | 0.610" | — | Scientific Cutting Tools | 9869N13 | 000000 | ——— | 0 | ——— | 0 | 5277N33 | 000000 | ||
| M16 × 1.5 mm | — | 3 3/8" | 1/2" | 1 7/8" | Round | 4 | 0.674" | — | Scientific Cutting Tools | 9869N14 | 000000 | ——— | 0 | ——— | 0 | 5277N33 | 000000 | ||
| M18 × 1.5 mm | — | 3 11/16" | 3/4" | 2 1/8" | Round | 4 | 0.743" | — | Scientific Cutting Tools | 9869N15 | 000000 | ——— | 0 | ——— | 0 | 5277N33 | 000000 | ||
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 | 04 | 3 13/32" | 5/8" | 1 7/8" | 2 | MS16142 | One 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 & Engineering | 9816N11 | 0000000 | 2 | 9816N17 | 0000000 | 2 | 9816N24 | 0000000 | 9816N31 | 00000 | 5277N26 | 0000000 | ||
| 9/16"-18 | 06 | 3 13/16" | 3/4" | 1 31/32" | 2 | MS16142 | One 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 & Engineering | 9816N12 | 000000 | 2 | 9816N18 | 000000 | 2 | 9816N25 | 000000 | 9816N32 | 0000 | 5277N28 | 000000 | ||
| 3/4"-16 | 08 | 3 15/16" | 3/4" | 1 31/32" | 2 | MS16142 | One 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 & Engineering | 9816N13 | 000000 | 2 | 9816N19 | 000000 | 2 | 9816N26 | 000000 | 9816N33 | 0000 | 5277N29 | 000000 | ||
SAE AS5202 | ||||||||||||||||||||||
| 7/16"-20 | 04 | 3 17/32" | 5/8" | 1 7/8" | 2 | MS33649 | One 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 & Engineering | 9816N14 | 000000 | 2 | 9816N21 | 000000 | 2 | 9816N27 | 000000 | 9816N31 | 0000 | 5277N26 | 000000 | ||
| 9/16"-18 | 06 | 3 29/32" | 3/4" | 1 31/32" | 2 | MS33649 | One 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 & Engineering | 9816N15 | 000000 | 2 | 9816N22 | 000000 | 2 | 9816N28 | 000000 | 9816N34 | 0000 | 5277N28 | 000000 | ||
| 3/4"-16 | 08 | 4 3/32" | 3/4" | 1 31/32" | 2 | MS33649 | One 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 & Engineering | 9816N16 | 000000 | 2 | 9816N23 | 000000 | 2 | 9816N29 | 000000 | 9816N33 | 0000 | 5277N29 | 000000 | ||
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 | 02 | Aluminum Titanium Nitride (AlTiN) Coated | One Step Drill Bit with Coolant Hole (Carbide) One Port Counterbore with Built-In Pilot (Carbide-Tipped Steel) One Thread Mill for Internal Threads (Carbide) | MS16142 | Scientific Cutting Tools | 9855N11 | 0000000 | 9851N11 | 0000000 | 9910N11 | 0000000 | 5277N24 | 0000000 | ||
| 3/8"-24 | 03 | Aluminum Titanium Nitride (AlTiN) Coated | One Step Drill Bit with Coolant Hole (Carbide) One Port Counterbore with Built-In Pilot (Carbide-Tipped Steel) One Thread Mill for Internal Threads (Carbide) | MS16142 | Scientific Cutting Tools | 9855N12 | 000000 | 9851N12 | 000000 | 9910N12 | 000000 | 5277N25 | 000000 | ||
| 7/16"-20 | 04 | Aluminum Titanium Nitride (AlTiN) Coated | One Step Drill Bit with Coolant Hole (Carbide) One Port Counterbore with Built-In Pilot (Carbide-Tipped Steel) One Thread Mill for Internal Threads (Carbide) | MS16142 | Scientific Cutting Tools | 9855N13 | 000000 | 9851N13 | 000000 | 9910N13 | 000000 | 5277N26 | 000000 | ||
| 1/2"-20 | 05 | Aluminum Titanium Nitride (AlTiN) Coated | One Step Drill Bit with Coolant Hole (Carbide) One Port Counterbore with Built-In Pilot (Carbide-Tipped Steel) One Thread Mill for Internal Threads (Carbide) | MS16142 | Scientific Cutting Tools | 9855N14 | 000000 | 9851N14 | 000000 | 9910N14 | 000000 | 5277N27 | 000000 | ||
| 9/16"-18 | 06 | Aluminum Titanium Nitride (AlTiN) Coated | One Step Drill Bit with Coolant Hole (Carbide) One Port Counterbore with Built-In Pilot (Carbide-Tipped Steel) One Thread Mill for Internal Threads (Carbide) | MS16142 | Scientific Cutting Tools | 9855N15 | 000000 | 9851N15 | 000000 | 9910N15 | 000000 | 5277N28 | 000000 | ||
| 3/4"-16 | 08 | Aluminum Titanium Nitride (AlTiN) Coated | One Step Drill Bit with Coolant Hole (Carbide) One Port Counterbore with Built-In Pilot (Carbide-Tipped Steel) One Thread Mill for Internal Threads (Carbide) | MS16142 | Scientific Cutting Tools | 9855N16 | 000000 | 9851N16 | 000000 | 9910N16 | 000000 | 5277N29 | 000000 | ||
SAE AS5202 | |||||||||||||||
| 5/16"-24 | 02 | Aluminum Titanium Nitride (AlTiN) Coated | One Step Drill Bit with Coolant Hole (Carbide) One Port Counterbore with Built-In Pilot (Carbide-Tipped Steel) One Thread Mill for Internal Threads (Carbide) | MS33649 | Scientific Cutting Tools | 9855N17 | 000000 | 9851N21 | 000000 | 9910N17 | 000000 | 5277N24 | 000000 | ||
| 3/8"-24 | 03 | Aluminum Titanium Nitride (AlTiN) Coated | One Step Drill Bit with Coolant Hole (Carbide) One Port Counterbore with Built-In Pilot (Carbide-Tipped Steel) One Thread Mill for Internal Threads (Carbide) | MS33649 | Scientific Cutting Tools | 9855N18 | 000000 | 9851N22 | 000000 | 9910N18 | 000000 | 5277N25 | 000000 | ||
| 7/16"-20 | 04 | Aluminum Titanium Nitride (AlTiN) Coated | One Step Drill Bit with Coolant Hole (Carbide) One Port Counterbore with Built-In Pilot (Carbide-Tipped Steel) One Thread Mill for Internal Threads (Carbide) | MS33649 | Scientific Cutting Tools | 9855N19 | 000000 | 9851N23 | 000000 | 9910N19 | 000000 | 5277N26 | 000000 | ||
| 1/2"-20 | 05 | Aluminum Titanium Nitride (AlTiN) Coated | One Step Drill Bit with Coolant Hole (Carbide) One Port Counterbore with Built-In Pilot (Carbide-Tipped Steel) One Thread Mill for Internal Threads (Carbide) | MS33649 | Scientific Cutting Tools | 9855N21 | 000000 | 9851N24 | 000000 | 9910N21 | 000000 | 5277N27 | 000000 | ||
| 9/16"-18 | 06 | Aluminum Titanium Nitride (AlTiN) Coated | One Step Drill Bit with Coolant Hole (Carbide) One Port Counterbore with Built-In Pilot (Carbide-Tipped Steel) One Thread Mill for Internal Threads (Carbide) | MS33649 | Scientific Cutting Tools | 9855N22 | 000000 | 9851N25 | 000000 | 9910N22 | 000000 | 5277N28 | 000000 | ||
| 3/4"-16 | 08 | Aluminum Titanium Nitride (AlTiN) Coated | One Step Drill Bit with Coolant Hole (Carbide) One Port Counterbore with Built-In Pilot (Carbide-Tipped Steel) One Thread Mill for Internal Threads (Carbide) | MS33649 | Scientific Cutting Tools | 9855N23 | 000000 | 9851N26 | 000000 | 9910N24 | 000000 | 5277N29 | 000000 | ||
