COUNTERBORES Technical Information
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Basics of...Counterbores
Counterbores are used to enlarge a portion of an existing hole to hide the head of a screw or to provide a seat for a nut. They come with solid or interchangeable pilots, and many are built for making holes for a specific type of fastener.
Types
Solid Pilot
- Manufactured with the pilot attached to the cutting end of the tool
- Provide a very accurate hole
Interchangeable Pilot
- Do not come with an attached pilot
- Separate pilot is attached by sliding the shank through a pilot-hole built into the counterbore
- Better flexibility, as a single tool can be used in many different hole diameters by switching the pilot
Use a Counterbore for:
- Socket head cap screws
- Machine screws
- Fillister head screws
- Spot facing