TWO THOUSAND YEARS AGO, Egyptian woodworkers figured out how to clamp two boards together, drill an angled hole through both, and insert a dowel to make a powerful joint.
Two decades ago, when Iowa tool and die maker Craig Sommerfeld sought an effective way to attach face frames to cabinets while hiding the screw heads, he used his engineering skills to revisit the joinery method, creating his now famous pocket-hole jig.
Pocket-hole joinery has come a long way since Craig’s first one-hole guide (the M1 Kreg Jig) hit the streets in 1990 (Photo A). Now, the product line includes everything from simple clamp-on jigs to fully-automated industrial versions used in kitchen cabinet and door factories.
A few competing pocket-hole jigs have entered the market, but no other company has come close to the Kreg range of products. Among them are the very simple Steelex jig from Woodstock International (Photo B), and a couple of more comprehensive offerings from Penn State Industries (PSI)—the Pocket-Hole Jig Junior System (Photo C) and the Pocket-Hole Jig Master System 3 (Photo D). All of them rely on the basic techniques and format developed by Sommerfeld.
POCKET-HOLE COMPETITORS: Like the Kreg pocket-hole jigs (top of the page and Photo A), the Steelex D1060 jig (B) and Penn State Industries’ Junior System PHJIGJR and Master System PHJIG3 (C, D) all provide a reliable way to join wood parts using specially designed screws.
Jig Options: clamp-on, bench-mounted, stand-alone
You can perform pocket-hole joinery with a very simple clamp-on jig, a more comprehensive bench-mounted jig such as the K3, or by stand-alone production machines designed for commercial shops, where no portable drill is required (cost-prohibitive so not covered here). The simplest of these options, the clamp-on one-hole jig, runs about $25, and usually includes a single-hole guide with a hardened bushing. Any shop clamp is used to secure the jig in position. The Kreg version of this guide comes as a kit with a step drill bit, a stop collar, and a hex key to lock the collar (Photo A), preceding page. The step drill bit cuts a pilot hole for the smooth part of the screw shaft, and a larger, flat-bottomed pocket hole to seat the screw head (Photo E), thereby allowing the screw to function as a clamp that draws in parts and holds them together.
Bench-mounted pocket-hole jigs include the Kreg K3 Master, PSI Pocket Hole Jig Junior System and PSI Jig Master System 3. Of these, the Kreg jig is far more versatile, and its price reflects this at $150. The PSI versions sell at $40 and $100, respectively. The former (the Junior version) uses a screw clamp instead of a toggle clamp to hold stock while drilling and fastening.
The Kreg K3 Master includes a portable base along with the bench-mounted clamping base. This portable system also is available separately for $80, and includes a K3 drill guide block (with three guide bushings), the portable base, a premium face clamp, a 3/8" step drill bit, a #2 square drive bit, a depth collar and Allen wrench, screws, a carrying case and instructions.
Pocket Hole Advantages
Time savings. A woodworker doesn’t need to wait for an hour or more while glue cures. Joined parts can be worked on immediately. Special self-tapping screws act as clamps, pulling mating parts together. Complicated clamping procedures are avoided.
Strength. Pocket-hole joints out-muscle biscuit and dowel joints.
Alignment. Edges align perfectly, so there is little or no sanding.
Versatility. Parts as narrow as 1¼" can be joined, and boards can be as wide as one wants. Should joints loosen for any reason, they can be retightened with a screwdriver.
Ease of Use. One joint can be worked on at a time, instead of having to glue and clamp several parts simultaneously. Large assemblies become a one-man job. No need for excessive accuracy during placement. Holes can be drilled anywhere.
Cosmetics. Screws can be hidden by drilling at the back of a joint. Visible or partially visible screws can be concealed using special plugs that take advantage of the pocket.
Mess Maintenance. By avoiding glue, cleanup consists of vacuuming up wood filings from drilling. Glue squeeze-out issues are nonexistent.
Super-simple joints in minutes
Making a pocket-hole joint typically begins with a butt joint. The mating parts must be accurately milled and positioned at 90° to each other. Check your machine fences and the blade tilt while you joint, surface (plane), and cut the parts to size to ensure precision.
Step 1: Establish the stop collar location
Different jigs have slightly different set-ups, but they all share the basics. The first of these is the use of a two-step drill bit with a stop collar that you lock to the bit. The location of the collar controls the hole depth. On the Kreg K3 Master Jig, there is a channel (like a half-pipe) where you can lay the bit and line it up with a mark that represents the thickness of the material being drilled (Photo F), preceding page. Then slide the stop collar along the bit until it touches the edge of the jig, and lock it in place with the provided Allen screw and wrench. Some jig manufacturers provide written directions for using a tape measure to establish the location of the stop collar.
Step 2: Jig up the part and drill the holes
Lock the part in the jig, as shown at the top of page 18, and drill the holes. On the standard 3-hole jig, one hole stands apart, while two others are close together. Use the two close-together holes for drilling stock that is 1¼" to 1¾" wide; use the next two closest holes for drilling material that is 1¾" to 2¾" wide (Photo G); and use the holes with the widest separation for stock that is 2¾" to 3¾" wide. For parts that are narrower than 1¼", use any one hole. On long mating parts, such as mating stiles, space holes no more than 5" apart.
Step 3: Assemble the parts
Next, clamp the mating parts together on the same plane, such as a flat workbench top, so that the finished joint is flush, flat and requires little if any sanding. Or, clamp the parts together using a deep-throated vise-grip (Photo H). Now drive home the special pocket-hole screws which are all self-tapping, meaning the screw point acts like a drill bit, so no pilot hole is needed in the mating piece. (This explains why only one workpiece needs to be drilled.) For more on screws, see the sidebar at left.
MATCH THE SCREW WITH THE MATERIAL
Choosing the right screw is important. You don’t want it so long that it emerges through the second workpiece, or so short that it fails to hold the joint together. While almost all pocket-hole screws are square-drive, several other factors come into play. Go with fine threads for hardwoods and coarse threads for softwood, plywood, particleboard, MDF (medium density fiberboard), and melamine-coated composite products. For MDF, a special screw with a large washer head is used where the wider head offers a better grip. In less dense softwoods such as poplar, a special screw called a Hi-Lo can be used. This has two separate threads that cut quickly and offer great holding power. For additional holding power, consider using glue, especially in mitered or stave joints and long, edge-to-edge joints (see the Most Suitable Pocket-Hole Applications, page 21).
Most jig manufacturers supply at least one extra-long square drive bit, which is essential in many joints where the angle of the pocket makes it difficult to reach around parts. Some are magnetized, and some aren’t.
The most suitable pocket-hole applications
Although pocket-hole joinery has various applications in the home construction field, it is widely popular among furniture makers who find it especially useful for these applications.
Pocket-hole plugs for a great coverup
Every now and then, pocket holes need to be used on a surface that will be seen. Some examples are the backs of cabinet doors when the door is open, or perhaps the underside of a shelf or mantle that is tall enough to be seen when people sit in chairs nearby. For that, the industry has developed pocket-hole plugs. These are simply round dowels cut at an angle to match the shape and size of the hole. They generally are glued and pushed into place, and then trimmed and sanded flush after the glue dries. A good way to do this is to place a piece of ¾" plywood scrap beside the plug, and use a straight bit chucked in a router to trim the excess (Photo I). The router base rides on the plywood, and the bit height is adjusted to barely touch the surface of the board surrounding the plug. They can be sanded flush with a random orbit sander.
Plugs are available in oak, maple, pine, walnut, cherry, cedar and a paint grade hardwood. Plastic versions come in brown, black, white, almond and light brown, and these are primarily used in melamine-coated and plastic laminated sheet stock, or to add an interesting accent to a hardwood project by using a contrasting color or species.
