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.

Technique

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.

Benefits

  • 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.

Drawbacks

  • A broken pocket-hole joint “likely can’t be repaired”.

Applications

There Many applications of pocket-hole joint:

1.  Angles

pocket hole join angle
Angle is also used to designate the measure of an angle or of a rotation. This measure is the ratio of the length of a circular arc to its radius. In the case of a geometric angle, the arc is centered at the vertex and delimited by the sides. In the case of a rotation, the arc is centered at the center of the rotation and delimited by any other point and its image by the rotation. Follow The Complete Guide.

2.  Aprons

apron
You can learn this here Source

3. Beveled corners

Beveled corners
Beveled edge refers to an edge of a structure that is not perpendicular to the faces of the piece. The words bevel and chamfer overlap in usage; in general usage they are often interchanged, while in technical usage they may sometimes be differentiated as shown in the image at right. A bevel is typically used to soften the edge of a piece for the sake of safety, wear resistance, or aesthetics; or to facilitate mating with another piece.

4. Curves

Curves
A closed curve is a curve that forms a path whose starting point is also its ending point—that is, a path from any of its points to the same point. See the source.

5.  Edge banding

edge banding
Edge Banding, or edgebanding, is the name of both a process and an associated narrow strip of material used to create durable and aesthetically pleasing trim edges during finish carpentry.
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

Edge joining
Edge jointing or just jointing is the process of making the edge of a wooden board straight and true in preparation for subsequent operations, often ultimately leading to joining two or more components together. Traditionally, jointing was performed using a jointer plane. Modern techniques include the use of a jointer machine, a hand held router and straight edge, or a table-mounted router.

7. Euro-style cabinets

Frameless cabinets, also known as European-style, skip the face frame, and the doors and drawers attach directly to the cabinet box. The look is more contemporary and interior access is easier.

8.  Face frames

Face frames
A face frame in cabinet making is the frame fixed to the front of a cabinet carcass which obscures the edges of the carcass and provides the fixing point for doors and other external hardware. A face frame provides strength to the front of a cabinet and is also considered a visual feature of particular styles of furniture.

9.  Cabinet frames

Cabinet Frame
A cabinet is a box-shaped piece of furniture with doors and/or drawers for storing miscellaneous items. Some cabinets stand alone while others are built in to a wall or are attached to it like a medicine cabinet. Cabinets are typically made of wood (solid or with veneers or artificial surfaces), coated steel (common for medicine cabinets), or synthetic materials. Commercial grade cabinets, which differ in the materials used, are called casework, casegoods, or case furniture.

10.  Leg rails

Leg rails
Learn and watch this video below about Leg to Rail Joinery Methods.

11. Picture frames

Picture frames
A picture frame is a decorative edging for a picture, such as a painting or photograph, intended to enhance it, make it easier to display or protect it

12.  Stairs

Stairs
A stairway, staircase, stairwell, flight of stairs, or simply stairs, is a construction designed to bridge a large vertical distance by dividing it into smaller vertical distances, called steps. Stairs may be straight, round, or may consist of two or more straight pieces connected at angles.

13.  Window jambs

Window jambs
A jamb (from French jambe, “leg”), in architecture, is the side-post or lining of a doorway or other aperture. The jambs of a window outside the frame are called “reveals.” Small shafts to doors and windows with caps and bases are known as “jamb-shafts”; when in the inside arris of the jamb of a window they are sometimes called “scoinsons.”

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.

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For a project that won’t be subjected to a lot of stress, screwing into the end grain can work, but a far better choice is to avoid this practice, especially when using softwoods such as pine.
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This may actually be stronger than screwing straight into face grain, because the angle will ensure a longer portion of the screw will be embedded in the wood.
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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.

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A regular screw would likely blast all the way through the pocket hole. A pocket screw has a wide head that rests on the little “shelf” made by the bit.
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In this cutaway, you can see the flat ledge the head of the screw will stop on.
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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.

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Lock the board in place with the lock down mechanism.
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With your drill set to its highest speed, start drilling holes. The collar will stop the bit.
Admire your hand crafted pocket holes!
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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:

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INCORRECT: In this direction the screw will be entering the end grain of the board and be weak.
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There is a chart on the back of the screw package to help you decide what length of screw to use.
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Since I use 3/” lumber so much I almost always use 1-1/4″ coarse thread screws. I like to keep a stock of these on hand.
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The boards need to be clamped together before driving the screws in place. Without clamping, the twisting of the screw will cause the boards to slip out of alignment and the joint won’t be flush and even.
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This long driver bit makes driving the square head screws simple.
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You might want to set the clutch on your drill to a low number so that it stops twisting when it reaches a certain tightness.
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For joining boards on their edges, you can hold them together with this right angle clamp. A bar clamp will work too.
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This is the correct way: the screw goes into the face grain of the board away from the end.
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Don’t screw them in with the tips pointing toward the outside edge of the board’s end. The screw doesn’t have enough wood to hold it in place.
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