Filter by
Pilot Diameter
Body Diameter
Sold As
Material
Pilot Length
Overall Length
Length
Manufacturer
Export Control Classification Number (ECCN)
DFARS Specialty Metals
Component
About Counterbores
%20--%3e%3csvg%20version='1.1'%20id='Layer_1'%20xmlns='http://www.w3.org/2000/svg'%20xmlns:xlink='http://www.w3.org/1999/xlink'%20x='0px'%20y='0px'%20viewBox='0%200%20400%20400'%20style='enable-background:new%200%200%20400%20400;'%20xml:space='preserve'%3e%3cstyle%20type='text/css'%3e%20.st0{fill:%231A70A0;}%20.st1{opacity:0.5;}%20%3c/style%3e%3cg%3e%3cg%3e%3cpath%20class='st0'%20d='M200,56.9c38.35,0,74.4,14.93,101.51,42.05c27.11,27.11,42.05,63.17,42.05,101.51s-14.93,74.4-42.05,101.51%20S238.35,344.02,200,344.02s-74.4-14.93-101.51-42.05c-27.11-27.11-42.05-63.17-42.05-101.51s14.93-74.4,42.05-101.51%20S161.65,56.9,200,56.9%20M200,12.9C96.41,12.9,12.44,96.88,12.44,200.46c0,103.59,83.97,187.56,187.56,187.56%20c103.59,0,187.56-83.97,187.56-187.56C387.56,96.88,303.59,12.9,200,12.9L200,12.9z'/%3e%3c/g%3e%3cg%3e%3cg%20class='st1'%3e%3cpath%20class='st0'%20d='M235.49,152.24h16.15l-27.46,111.87c-1.94,7.8-2.91,12.5-2.91,14.1c0,1.82,0.58,3.29,1.73,4.41%20c1.16,1.12,2.69,1.68,4.61,1.68c5.23,0,11.78-3.85,19.63-11.55l17.22,21.34c-16.95,17.33-34.87,26-53.78,26%20c-8.37,0-15.45-1.47-21.23-4.41c-5.79-2.94-10.44-7.25-13.95-12.92c-3.51-5.67-5.27-11.18-5.27-16.53c0-1.93,0.35-5.24,1.05-9.94%20c1-6.94,2.05-12.54,3.15-16.82l15.22-62.15h-32.69l7.65-30.97C190.89,163.58,214.53,158.88,235.49,152.24z%20M230.44,80.84%20c8.24,0,14.66,2.62,19.26,7.86c4.6,5.24,6.9,11.55,6.9,18.94c0,5.46-1.42,10.7-4.25,15.73c-2.83,5.03-6.88,9.07-12.12,12.12%20c-5.24,3.05-10.33,4.57-15.24,4.57c-4.6,0-9.17-1.23-13.72-3.69c-4.55-2.46-8.02-5.78-10.43-9.95%20c-2.41-4.17-3.61-8.67-3.61-13.48c0-5.35,1.52-10.64,4.57-15.89c3.05-5.24,7.03-9.25,11.96-12.04%20C218.68,82.23,224.24,80.84,230.44,80.84z'/%3e%3c/g%3e%3cg%3e%3cpath%20class='st0'%20d='M214.08,152.24h16.15l-27.46,111.87c-1.94,7.8-2.91,12.5-2.91,14.1c0,1.82,0.58,3.29,1.73,4.41%20c1.16,1.12,2.69,1.68,4.61,1.68c5.23,0,11.78-3.85,19.63-11.55l17.22,21.34c-16.95,17.33-34.87,26-53.78,26%20c-8.37,0-15.45-1.47-21.23-4.41c-5.79-2.94-10.44-7.25-13.95-12.92c-3.51-5.67-5.27-11.18-5.27-16.53c0-1.93,0.35-5.24,1.05-9.94%20c1-6.94,2.05-12.54,3.15-16.82l15.22-62.15h-32.69l7.65-30.97C169.48,163.58,193.11,158.88,214.08,152.24z%20M209.03,80.84%20c8.24,0,14.66,2.62,19.26,7.86c4.6,5.24,6.9,11.55,6.9,18.94c0,5.46-1.42,10.7-4.25,15.73c-2.83,5.03-6.88,9.07-12.12,12.12%20c-5.24,3.05-10.33,4.57-15.24,4.57c-4.6,0-9.17-1.23-13.72-3.69c-4.55-2.46-8.02-5.78-10.43-9.95%20c-2.41-4.17-3.61-8.67-3.61-13.48c0-5.35,1.52-10.64,4.57-15.89c3.05-5.24,7.03-9.25,11.96-12.04%20C197.26,82.23,202.83,80.84,209.03,80.84z'/%3e%3c/g%3e%3c/g%3e%3c/g%3e%3c/svg%3e){kind=small}
Create flat-bottomed holes, so your screw heads sit flush, recessed, or slightly raised.
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 | 28225A64 | 000000 | ||
| 1" | 1.526" | 1.016" | 1.000" | 8 1/2" | 1" | Round | 4 | Alvord-Polk Tool | 2919A65 | 000000 | 28225A65 | 000000 | ||
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 | 28225A84 | 000000 | ||
| 1" | 1.541" | 1.031" | 1.000" | 8 1/2" | 1" | Round | 4 | Alvord-Polk Tool | 2919A85 | 000000 | 28225A85 | 000000 | ||
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 | ——— | 0 | ||
| M4 | 7.5 mm | 4.5 mm | 0.250" | 5" | 1/4" | Round | 4 | Alvord-Polk Tool | 2740A12 | 00000 | ——— | 0 | ||
| M5 | 9.0 mm | 5.5 mm | 0.281" | 5 5/8" | 5/16" | Round | 4 | Alvord-Polk Tool | 2740A13 | 00000 | ——— | 0 | ||
| M6 | 10.5 mm | 6.5 mm | 0.313" | 5 5/8" | 5/16" | Round | 4 | Alvord-Polk Tool | 2740A14 | 00000 | ——— | 0 | ||
| M8 | 13.5 mm | 8.5 mm | 0.375" | 6 1/2" | 1/2" | Round | 4 | Alvord-Polk Tool | 2740A15 | 00000 | ——— | 0 | ||
| M10 | 16.5 mm | 10.5 mm | 0.500" | 7" | 1/2" | Round | 4 | Alvord-Polk Tool | 2740A16 | 00000 | ——— | 0 | ||
| M12 | 18.5 mm | 12.5 mm | 0.500" | 7 1/8" | 1/2" | Round | 4 | Alvord-Polk Tool | 2740A17 | 00000 | ——— | 0 | ||
| 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.
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 | ||||||||||||
| 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 | ||
C5 Carbide | ||||||||||||
1/64" Oversize | ||||||||||||
| 1/4" | 0.398" | 17/64" | 0.313" | 5 5/8" | 5/16" | Round | 3 | Rock River Tool | 3218A213 | 000000 | ||
| 5/16" | 0.491" | 21/64" | 0.375" | 6 1/8" | 3/8" | Round | 3 | Rock River Tool | 3218A223 | 000000 | ||
| 3/8" | 0.588" | 25/64" | 0.500" | 6 1/2" | 1/2" | Round | 3 | Rock River Tool | 3218A233 | 000000 | ||
| 7/16" | 0.679" | 29/64" | 0.500" | 7" | 1/2" | Round | 3 | Rock River Tool | 3218A243 | 000000 | ||
| 1/2" | 0.773" | 33/64" | 0.500" | 7 1/2" | 1/2" | Round | 3 | Rock River Tool | 3218A253 | 000000 | ||
| 5/8" | 0.961" | 41/64" | 0.625" | 7 5/8" | 5/8" | Round | 3 | Rock River Tool | 3218A263 | 000000 | ||
| 3/4" | 1.149" | 49/64" | 0.750" | 7 3/4" | 3/4" | Round | 3 | Rock River Tool | 3218A273 | 000000 | ||
| 7/8" | 1.338" | 57/64" | 0.875" | 8 1/8" | 7/8" | Round | 4 | Rock River Tool | 3218A283 | 000000 | ||
| 1" | 1.526" | 1 1/64" | 1.000" | 8 1/2" | 1" | Round | 4 | Rock River Tool | 3218A293 | 000000 | ||
1/32" Oversize | ||||||||||||
| 1/4" | 0.413" | 9/32" | 0.313" | 5 5/8" | 5/16" | Round | 3 | Rock River Tool | 3218A212 | 000000 | ||
| 5/16" | 0.506" | 11/32" | 0.375" | 6 1/8" | 3/8" | Round | 3 | Rock River Tool | 3218A222 | 000000 | ||
| 3/8" | 0.603" | 13/32" | 0.500" | 6 1/2" | 1/2" | Round | 3 | Rock River Tool | 3218A232 | 000000 | ||
| 7/16" | 0.694" | 15/32" | 0.500" | 7" | 1/2" | Round | 3 | Rock River Tool | 3218A242 | 000000 | ||
| 1/2" | 0.788" | 17/32" | 0.500" | 7 1/2" | 1/2" | Round | 3 | Rock River Tool | 3218A252 | 000000 | ||
| 5/8" | 0.976" | 21/32" | 0.625" | 7 5/8" | 5/8" | Round | 3 | Rock River Tool | 3218A262 | 000000 | ||
| 3/4" | 1.164" | 25/32" | 0.750" | 7 3/4" | 3/4" | Round | 3 | Rock River Tool | 3218A272 | 000000 | ||
| 7/8" | 1.353" | 29/32" | 0.875" | 8 1/8" | 7/8" | Round | 4 | Rock River Tool | 3218A282 | 000000 | ||
| 1" | 1.541" | 1 1/32" | 1.000" | 8 1/2" | 1" | Round | 4 | Rock River Tool | 3218A292 | 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 | ||
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.
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 | ||||||||||||
| 1/4" | 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 | ||
C5 Carbide | ||||||||||||
| 1/4" | 0.382" | 1/4" | 0.313" | 5 5/8" | 5/16" | Round | 3 | Rock River Tool | 3218A211 | 000000 | ||
| 5/16" | 0.475" | 5/16" | 0.375" | 6 1/8" | 3/8" | Round | 3 | Rock River Tool | 3218A221 | 000000 | ||
| 3/8" | 0.572" | 3/8" | 0.500" | 6 1/2" | 1/2" | Round | 3 | Rock River Tool | 3218A231 | 000000 | ||
| 7/16" | 0.663" | 7/16" | 0.500" | 7" | 1/2" | Round | 3 | Rock River Tool | 3218A241 | 000000 | ||
| 1/2" | 0.757" | 1/2" | 0.500" | 7 1/2" | 1/2" | Round | 3 | Rock River Tool | 3218A251 | 000000 | ||
| 5/8" | 0.945" | 5/8" | 0.625" | 7 5/8" | 5/8" | Round | 3 | Rock River Tool | 3218A261 | 000000 | ||
| 3/4" | 1.133" | 3/4" | 0.750" | 7 3/4" | 3/4" | Round | 3 | Rock River Tool | 3218A271 | 000000 | ||
| 7/8" | 1.322" | 7/8" | 0.875" | 8 1/8" | 7/8" | Round | 4 | Rock River Tool | 3218A281 | 000000 | ||
| 1" | 1.510" | 1" | 1.000" | 8 1/2" | 1" | Round | 4 | Rock River Tool | 3218A291 | 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 | No. of Pieces | Shank Type | No. of Flutes | 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" | 10 | Round | 4 | Alvord-Polk Tool | 2919A12 | 0000000 | ||
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 | 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" | 10 | 1/64" | Round | 4 | 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" | 10 | 1/32" | Round | 4 | Alvord-Polk Tool | 2919A16 | 000000 | ||
| M3, M4, M5, M6, M8, M10, M12, M14 | 8 | 0.5 mm | Round | 4 | Alvord-Polk Tool | 2740A19 | 000000 | ||
Counterbore Insert Holders
 |
Shown with Inserts (Sold Separately) |
Designed to reduce waste and costs during high-volume jobs, these counterbores consist of both an insert and a holder. When the cutting edges dull, you can replace the insert rather than the entire tool. The inserts are locked in place with a screw for a hold that’s strong enough to handle the high speeds of a CNC machine. These counterbores create flat-bottomed holes that allow socket head screws to sit flush with the surface of your material.
Counterbore Insert Holders | Replacement Insert Screws | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Dia. | |||||||||||||
For Screw Size | Body | Shank | Overall Lg. | Max. Hole Drilling Dp. | No. of Inserts Req. | Mfr. | Each | Pkg. Qty. | Pkg. | ||||
Steel | |||||||||||||
| 1/4" | 0.422" | 3/4" | 2 7/8" | 0.54" | 1 | Kyocera | 8129N122 | 0000000 | 10 | 8129N133 | 000000 | ||
| 5/16" | 0.515" | 3/4" | 2 7/8" | 0.54" | 1 | Kyocera | 8129N125 | 000000 | 10 | 8129N133 | 00000 | ||
| 3/8" | 0.515" | 3/4" | 2 7/8" | 0.54" | 1 | Kyocera | 8129N124 | 000000 | 10 | 8129N133 | 00000 | ||
| 7/16" | 0.703" | 3/4" | 2 7/8" | 0.54" | 1 | Kyocera | 8129N127 | 000000 | 10 | 8129N133 | 00000 | ||
| 1/2" | 0.797" | 3/4" | 3 1/4" | 0.79" | 2 | Kyocera | 8129N121 | 000000 | 10 | 8129N133 | 00000 | ||
| 5/8" | 1" | 3/4" | 3 1/4" | 0.79" | 2 | Kyocera | 8129N126 | 000000 | 10 | 8129N133 | 00000 | ||
| 3/4" | 1.187" | 3/4" | 3 1/4" | 0.79" | 2 | Kyocera | 8129N123 | 000000 | 10 | 8129N133 | 00000 | ||
| M6 | 0.440" | 3/4" | 2 7/8" | 0.54" | 1 | Kyocera | 8129N131 | 000000 | 10 | 8129N133 | 00000 | ||
| M8 | 0.558" | 3/4" | 2 7/8" | 0.54" | 1 | Kyocera | 8129N132 | 000000 | 10 | 8129N133 | 00000 | ||
| M10 | 0.676" | 3/4" | 2 7/8" | 0.54" | 1 | Kyocera | 8129N128 | 000000 | 10 | 8129N133 | 00000 | ||
| M12 | 0.755" | 3/4" | 3 1/4" | 0.79" | 2 | Kyocera | 8129N129 | 000000 | 10 | 8129N133 | 00000 | ||
 |  |
Individual Carbide Insert Case |
Inserts have a positive rake, which means the cutting edge is angled to reduce vibration and prevent thin workpieces from bending. For longer life, each insert has three cutting edges—when one edge dulls, rotate to the next one. They have chip breakers to stop long chips from forming, so they won’t block the flow of coolant or damage your tool. Inserts sold individually come packed in a clear plastic case to protect cutting edges during shipment. Inserts sold in packs come factory sealed from the manufacturer for maximum traceability.
