Pocket-hole joinery, or pocket-screw joinery, involves drilling a hole at an angle — usually 15 degrees — into one work piece, and then joining it to a second work piece with a self-tapping screw. The technique, in addition to doweling, is said to have its roots in ancient Egypt, although much doubt is thrown on this theory. Older woodworking reference books never mention the technique of pocket-hole joinery and contemporary woodworking references describe it as new and nontraditional.
Improvements in pocket hole jig technology in recent years have made pocket joints not only easy but often preferred in certain applications such as many types of face frames.
There are numerous different styles of pocket joints, but the basic idea is a jig with a machined aluminum guide cylinder is positioned at a precise angle in the jig. The jig is then clamped to the headboard, and a particular bit the same diameter as the hole (with a much smaller bit on the tip) is used to drill through the aluminum cylinder into the headboard.
Once the pocket hole has been drilled in the headboard, the tailboard is clamped into place, and a screw is driven through the pocket hole into the tailboard. If the glue is to be added to strengthen the joint, it should be placed on the mating surface between the tailboard and headboard before inserting the screw.
Pocket hole jigs
Pocket holes can be formed by drilling a series of holes until a pocket hole is created, but pocket hole jigs make the process much quicker and easier. Pocket hole jigs allow the user to drill a hole at an accurate angle to get a good joint. Using a pocket hole jig also makes for a cleaner and neater appearance as opposed to creating a pocket hole without the help of a jig. A pocket hole jig is generally made of plastic and has a metal insert that the drill bit is inserted through to drill the hole. A jig can be a stationary device that the wooden pieces are clamped into, or a portable device that is clamped onto the wooden pieces.
When joining boards at a right angle, it is important that the cuts are precise and square to prevent gaps or un-perpendicular joints between the boards. Some woodworkers lay out their project before drilling their pocket holes and mark the face of the board that they want to drill to ensure the hole is in the correct location. Most pocket joints are made by screwing into the face or the edge of the board rather than the end grain because the screw will grab better.
Pocket hole joint screws
Self tapping pocket screws are used for pocket hole joints. Pocket screws are generally more expensive, but they are needed for a tight, strong joint. Pocket screws have a wide washer head to prevent screwing too far into the joint and cracking the wood. The self tapping screws will grip any type of wood, but coarse threads are needed for softer wood and fine threads are needed for harder wood.
- Because the screws act as internal clamps holding the joint together, glue is unnecessary (but usually recommended) for most common joints. If glue is used, clamping is not required because of the ‘internal clamps’ holding the joint together while the glue dries.
- Gluing and screwing the joints together prevents gaps from forming as wood shrinks and expands with temperature and moisture.
- Requires only one hole to be drilled, eliminating the need to precisely line up mating workpieces, as is required with dowel and mortise and tenon joints.
- Does not require any complex mathematics or measurements, such as those used in mortise and tenon joints.
- Because pocket-hole joinery doesn’t require access to the inside of the joint, quick repairs are possible without completely disassembling the joint. Fixing a squeaky chair or strengthening furniture requires only the drilling of additional pocket holes, and the use of screws to pull the two pieces together.
- Pocket hole joints have been proven to be superior to traditional joinery. A comparable mortise and tenon joint failed at 453 pounds under a shear load while a pocket hole joint failed at 707 pounds.
- A broken pocket-hole joint “likely can’t be repaired”.
There Many applications of pocket-hole joint:
3. Beveled corners
5. Edge banding
Edge banding is used to cover the exposed sides of materials such as plywood, particle board or MDF, increasing durability and giving the appearance of a solid or more valuable material. Common substitutes for edgebanding include face frames or molding. Edge banding can be made of different materials including PVC, ABS, acrylic, melamine, wood or wood veneer.
6. Edge joining
7. Euro-style cabinets
8. Face frames
9. Cabinet frames
10. Leg rails
11. Picture frames
13. Window jambs
HOW POCKET HOLE JOINERY WORKS
The important thing to always keep in mind, whether you are using pocket screws or not, is that screwing into the end grain of a board provides the weakest connection.
THE DRILL BIT AND SCREWS
A pocket hole’s stepped drill bit has a narrow tip to guide the screw and a wider part to bore the pocket hole.
DRILLING THE POCKET HOLES
The nice thing about pocket hole joinery is that you only have to drill a hole in one board: you don’t have to drill a matching hole in its mating piece like you would for a dowel joint. This allows for a lot of flexibility when positioning your holes. Anywhere you place them on the board it fine.
SCREWING THE BOARDS TOGETHER
Make sure the board the screw will be driving into is the face or edge grain board. This is the correct way: