Pockethole
Pockethole joints are a quick and easy way for DIY enthusiasts to join workpieces together. To do this, so-called pocket holes are drilled into a workpiece at a shallow angle and the parts are connected with special screws. Correctly positioned, concealed screw connections are possible. In this tutorial, you will learn everything you need to know about the correct use of pocket hole connections.
How do you make pocket holes?
So-called "undercover jigs" or "pocket hole jigs" are used to drill pocket holes. These allow holes to be drilled at a shallow angle to the workpiece surface, in which the matching screws disappear completely. Without jigs, it is not possible to drill a hole at such a shallow angle. The jig gives the drill the correct angle from the outset. Pocket holes can also be found on old furniture. However, these were not usually drilled, but rather chiselled with chisels or gouges.
Fig.: Drilling at such a flat angle to the surface is only possible with a template.
Important to know: When using screws to join wood, the grain direction must be observed. If a screw is screwed in in the direction of the grain, it will cut through the wood fibres that are supposed to hold the screw several times. Screws screwed in in the direction of the grain are therefore comparatively easy to pull out and offer less support. If screws are screwed in at right angles to the grain, they are supported laterally by the fibres and the connection holds much better. Attention must also be paid when using pocket holes. A pocket hole can be drilled diagonally lengthways to the fibre (with the fibre) or diagonally crossways, but screws are always screwed into transverse fibres. Another aspect that plays an important role when using pocket holes is the shrinkage behaviour of wood - more on this later.
Which timber joints are pocket-hole joints suitable for?
If you follow the basic principles mentioned above, pocket-hole joints are suitable for all types of timber joints, i.e. frame joints, carcass joints and surface joints. There are different pocket-hole jigs for mobile and stationary use. For example, you can use a stationary drilling template to quickly and efficiently pre-drill the workpieces in your workshop, or use a small mobile jig to determine the position of the holes during assembly.
What is a jig drill?
In order to screw two wooden parts together flush and countersink the screw at the same time, three holes with different diameters would basically have to be drilled:
- Hole in the diameter of the head,
- hole in the diameter of the screw shank and a
- hole in the core diameter of the screw thread.
The 1st and 2nd holes are drilled with the drilling aid and are the actual pocket hole. This hole is drilled with the so-called jig drill, which is a stepped drill that is usually included with the drilling template or jig. The third hole on the other workpiece is drilled by so-called "self-tapping screws" during assembly.
Which screws do I use for pocket hole joints?
Special pocket hole screws are available for screwing pocket holes or pocket hole joints. These are flat-head screws whose head is flush with the base of the stepped hole. Countersunk head screws are unsuitable for pocket hole connections as they would split the wood when screwed. Most manufacturers of pockethole jigs offer suitable screws (e.g. included in the complete set from UJK ). Alternatively, you can also use so-called self-tapping backing screws.
Pocket hole screws are self-tapping and work quite well with soft types of wood and panel materials; with harder woods, splitting in the direction of the grain can occur. It is therefore important to use the right type of screw for the type of wood or material. For softwood (spruce, pine, etc.), chipboard or OSB boards, these have a coarse thread, while screws with a fine thread are used for hardwood (oak, ash, beech, etc.).
The length of the screws depends on the material thickness. The position of the exit point of the screw should be as close as possible to the centre of the edge of the workpiece. With most Pockethole drilling templates, you can set a stop to the material thickness. With very thick material (e.g. when joining beams), it can be useful to drill pocket holes from both sides.
Where can I drill a pocket hole?
Fig.: Our example for the use of pocket hole connections: a small stool
If possible, position all pocket holes or pocket hole connections so that they are concealed by other workpieces. To do this, you can drill the pocket holes on the inside of the body, for example. In our example stool, we have drilled all the holes on the inside or on the underside of the parts. In the video, we have screwed all parts flush with each other. However, you can achieve more stability if you offset the side parts and upper cross struts slightly inwards (approx. 5 to 10 mm). There will then be more material on the outer edge to provide additional support for the screws. If the pocket holes are later concealed by a worktop or a decorative frame, for example, you can also position the drilling jig on the outside.
When constructing your furniture, also consider the shrinkage behaviour of wood: solid wood works much more strongly in the radial and tangential direction (across the grain) than in the longitudinal direction. So if possible, only screw lengthwise wood to lengthwise wood and crosswise wood to crosswise wood. In the case of our stool, the grain runs all the way round: the side sections, the seat and the lower cross strut can "work" together in the same direction. Only in the upper cross struts does the cross grain meet the longitudinal grain. However, the struts are only 80 mm wide, so their shrinkage behaviour can be neglected.
Which screwdriver for pocket hole screws?
An extended bit is required to screw in the Pockethole screws at a shallow angle (normal bits are too short, the drill chuck or screwdriver could hit the surface and soil or scratch it). Some manufacturers, e.g. Kreg, use a special drive shape or slotted shape for their screws. In the case of Kreg screws, this is an internal square drive. You need special bits for these drives.
FAQs on the topic of pockethole connections
How do I hold the parts together when screwing them together?
Many manufacturers offer special clamps with which you can clamp workpieces with pocket holes flush together. Alternatively, you can clamp two stop bars at right angles on the worktable and use them to align your workpieces. This is usually quicker and also works well with larger furniture parts.
Which holds better: Pockethole, wooden dowel, flat spring or domino?
Compared to other fastening systems such as Duodübler, Domino and Lamello, pocket hole joints are slightly less stable. However, if you additionally glue the joints or parts together, this already provides a considerable increase in load-bearing capacity. You can also combine pocket holes with other connection systems. For example, you can use lamellas, dominoes or wooden dowels to ensure precise positioning of the parts and use pocket hole connections to enable assembly without clamps.
My cordless screwdriver doesn't fit into the piece of furniture. What can I do?
With smaller furniture or furniture parts (e.g. drawers), this can mean that there is not enough space for the cordless screwdriver or drill inside the cabinet. In this case, use a hand screwdriver or a drilling winch with ratchet function or attach the pocket hole on the outside.
Conclusion
Pockethole joints offer you quick and easy ways to join wooden parts together. You only need a few tools, such as a cordless screwdriver, a pockethole jig with a suitable step drill and an extra-long screw bit. Pocketholes are well suited for corner joints, T-joints, frame corners and furniture carcasses. Placed in the right places, pockethole joints are almost invisible and very stable.
If we have inspired you and you would now like to get started with a pockehole jig, you will find high-quality drilling templates and accessories from quality manufacturers such as UJK and Kreg in our online shop.
