About Counterbores
Create flat-bottomed holes, so your screw heads sit flush, recessed, or slightly raised.
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 Steel
 |  |
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 | Each | Shank Dia. | Overall Lg. | Each | ||||
| 5/16" | 1/2" | 4 | 0000000 | 000000 | 3/32" | 6" | 0000000 | 00000 | ||
| 5/16" | 1/2" | 4 | 0000000 | 00000 | 1/8" | 6" | 0000000 | 0000 | ||
| 5/16" | 1/2" | 4 | 0000000 | 00000 | 5/32" | 6" | 0000000 | 0000 | ||
| 3/8" | 1/2" | 4 | 0000000 | 00000 | 1/8" | 6" | 0000000 | 0000 | ||
| 3/8" | 1/2" | 4 | 0000000 | 00000 | 5/32" | 6" | 0000000 | 0000 | ||
| 3/8" | 1/2" | 4 | 0000000 | 00000 | 3/16" | 6" | 0000000 | 00000 | ||
| 1/2" | 1/2" | 4 | 0000000 | 00000 | 5/32" | 6" | 0000000 | 0000 | ||
| 1/2" | 1/2" | 4 | 0000000 | 00000 | 3/16" | 6" | 0000000 | 00000 | ||
| 1/2" | 1/2" | 4 | 0000000 | 00000 | 1/4" | 6" | 0000000 | 00000 | ||
