Find the bore before
you drill the blank.

The standard straight-shank drill family used for many kit bores. Match the exact diameter in the kit instructions and clear chips frequently in deep blanks.

A wood-focused drill with a locating point and rim spurs. It can start accurately in a blank, but the required kit diameter still controls the final choice.

A deep-hole drill style with open flutes that help move chips out of long pen and project blanks. Use the size specified by the kit maker.

A rim-guided drill for flat-bottomed or larger bores. Use it only when the kit instructions call for that form and exact diameter.

Imperial drill sizes written as fractions, such as 3/8 in or 27/64 in. Similar-looking sizes are not interchangeable when tube fit is critical.

Drill sizes specified in millimeters. Keep the instruction value in metric rather than rounding to a nearby fractional size unless the kit maker lists an alternative.

North American letter-gauge drills such as J, O, or V. The letter is the size designation, so use the exact letter called out in the instructions.

Number-gauge drills use designations such as #7. The number is a defined diameter, not a count or product quantity.