Determining Countersink Screw Hole Size

Many people will countersink a screw when they want to hide the screw head or want a flush finish. Some screws are also created in such a way that the head is beveled for countersinking. This countersink is actually a larger hole that is drilled after the regular screw hole has been done. A countersunk screw gives a great finished look to items like furniture or antique pieces.

Determine Size of Countersink

One of the problems that some people have is how to determine the size of the countersink for the screw head. If the countersink is too deep, the screw will be too far into the wood. If it is too shallow, the head will not fit flush. There is a simple formula for determining this countersink.

A Simple Formula

In order to get the right countersink for a screw, you will need to do a little math. Take the measurement of the overall depth length of the screw. Then, measure the diameter of the screw. Divide this diameter by 2 in order to get the radius. Once you know all of these numbers, then you simply plug them into a formula. The right countersink hole is determined by squaring the radius and then multiplying that by the constant pi. Take that number and multiply by the length of the screw, and you have the depth for your countersink.