Tip #91
How to Counterbore For Screws
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Description:
Counterboring is increasing the diameter of part of a hole. When the clearance hole for a wood screw is counterbored to receive the screw head, it is necessary to increase the depth of the clearance and pilot holes an amount equal to the length of the counterbore. The size of the counterbore is made large enough to accommodate the entire head of the screw below the surface of the stock. Counterboring may be done before clearance and pilot holes are drilled. However, since counterbores usually have removable pilots, such drilling may be done last.

Fig. 1 Click image for larger view.

Use:
Counterboring of screw holes is used: a) to allow the root of the screw to enter the stock to be joined when the thickness of the stock counterbored is greater than the length of the screw. b) to cover the screw head with a wood plug. The plug may be required for concealment, protection, or decoration.

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