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What Is a Forstner Drill Bit?

Christina Edwards
Christina Edwards

The Forstner drill bit was invented in the 19th century by a gunsmith. This type of drill bit has a sharp point surrounded by circular cutting edges. It can be used to drill holes with flat bottoms, as well as angled holes and overlapping holes. Since a lot of force must be applied to the bit for it to work properly, a Forstner bit is usually found in a drill press instead of a hand-held drill. These types of drill bits also come in a variety of sizes.

Benjamin Forstner was a gunsmith born in 1834 in Beaver County, Pennsylvania. Along with being a gunsmith, Forstner was an inventor. He invented an electric motor as well as a special drill bit, known as the Forstner drill bit.

A drill with a Forstner bit.
A drill with a Forstner bit.

A Forstner drill bit consists of a long shank with sharp tip in the center. This tip is used to initially guide the bit into the start of the hole. The tip is also surrounded by a cylindrical cutting edge, which is necessary for boring holes. Flat cutting edges run from the circular cutting edge to the center point, and these are necessary for removing wood from the bottom of the bored hole.

Due to its unique design, the Forstner drill bit is capable of boring holes with flat bottoms. Since it is guided by the cutting edges on the side and not the center point, this type of drill bit is also useful for boring holes in wood with imperfections, like knots. Regular wood drill bits are often thrown off center when they are used to bore holes into this type of wood.

A Forstner drill bit can also be used to drill at an angle. Unlike regular drill bits, they can also be used to make holes that overlap. One would also use a Forstner bit to bore partial holes into the edge of a piece of wood.

Forstner drill bits usually require a decent amount of force for them to work. For this reason, they are not usually recommended for normal hand held drills, since users would have to press on the drill very hard. Instead, they are usually used with drill presses. When using a Forstner drill bit, one will also typically need to remove pieces of wood from the hole as the bit bores through the wood.

Several Forstner drill bit sizes are available. These can usually be found in both imperial and metric sizes. Forstner drill bit sets typically come with several drill bits of varying sizes. A consumer also has the option to purchase a single Forstner drill bit of a certain size.

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    • A drill with a Forstner bit.
      By: Amy Walters
      A drill with a Forstner bit.