How a Pocket-Hole Joint Works

posted 1/14/2019 in Kreg Tool Tips: Joining by Kreg Tool


An Inside Look at Pocket-Hole Joints
Creating a pocket-hole joint is easy. As we like to say, with a Kreg®  Pocket-Hole Jig, it’s as easy as Drill. Drive. Done. To see how a pocket-hole joint comes together, though, it’s fun to take a look inside. That’s what we’ll do here.

A Kreg Pocket-Hole Jig gets set up to match the thickness of the material you’re working with. The reason for this can be seen in the illustration, which shows the board transparently. When you drill, the very tip of the pocket hole gets positioned roughly at the center of the material’s thickness. This ensures there’s plenty of wood around the hole for maximum strength. We’re showing with a benchtop-style jig, here, but it works the same whatever Kreg Pocket-Hole Jig you are using.



The Angle Creates the Oval
As you drill, the stepped drill bit enters the wood at a 15° angle. That’s what creates the distinctive oval shape. The Pocket-Hole-Jig ensures this angle is consistent, and that the bit is held steady as you work, making the process of drilling an angled hole foolproof.


Double-Duty Drill Bit
If you look “inside” the material again, you can clearly see what happens as you drill the pocket hole. The special stepped drill bit does two things: The smaller tip drills a pilot hole for the screw, while the main part of the bit drills the pocket that the screw fits into.


Parts of the Pocket
A cutaway view of the pocket hole shows all the elements, in another way. At the base of the pocket, there’s a flat ledge that the head of the screw will contact. The pilot hole continues almost—but not quite all the way—to the end of the board. It stops short for good reason: To prevent the wood fibers from “blowing out” as the bit would exit the material. That way, there’s nothing to interfere with this piece fitting tightly against the mating piece.


Self-Tapping Screws Keep It Simple
The pocket hole makes this type of joint possible, but it’s the Kreg Pocket-Hole Screw that pulls it all together. As you drive the screw in, the pocket and pilot hole guide the screw precisely, while the screw’s self-tapping tip drills its own hole into the mating piece. That means you don’t have to drill into both pieces, and you’ll get great holding power without splitting or stripping the wood.

VIDEO: How To Choose the Correct Kreg Screw


Kreg Screws Pull It All Together
As you tighten the Kreg Pocket-Hole Screw, it pulls the joint tightly together. The process is simple, but there are several things going on that make it possible. For starters, the upper part of the screw doesn’t have threads. That lets it turn easily inside the pilot hole and pull the pieces together, rather than driving them apart.

Second, the flat underside of the screw mates perfectly with the ledge at the base of the pocket. This way, the head pulls the joint tightly together to create a super-strong, lasting joint.

Learn more at kregtool.com/screws.