There are many different techniques for joining to pieces of timber, both traditional and modern. One that is proving quite resilient is pocket hole joinery. It is a modern development of the more traditional “glue and screw” method, and using a fundamentally simple concept, produces a surprisingly strong joint, even when glue is not used. Although I call it a modern joint (with Kreg developing the modern pockethole jig in 1986), the ancient Egyptians were using a version of it, inserting a dowel through the angled hole, then cutting it flush with the surface.
The pockethole is created by drilling a partial-depth hole at an angle into one member of the joint. It stops short of cutting all the way through, and the drill bit is profiled so the hole drilled has a flat bottom. This provides a good square surface for the flat-headed screws to press against. The clever part of the drill bit, is it has two diameters. The main diameter cuts the slot, and the flat bottomed hole. In the centre of this hole, another is cut that is just larger than the diameter of the screw itself, so it acts as a pilot hole to control the direction of the screw as it is tightened, and helps prevent splitting.
The drill bit depth is controlled with a metal sleeve that has a grub screw to set the depth of hole. Readings on the jig itself allow you to set the correct depth based on material thickness.
Setting bit depth
The screws can be any brand that is suitably sized, and has a flat-bottomed head, but the ones that are most commonly used are the Robertson Screw. Instead of having a Phillips, or flat drive, they use a square drive that actually predates the Phillips headed screw. This type of drive provides a number of advantages in this scenario, but it boils down to one thing. Ease of use.
Robertson Square-Drive Screw
Ready to Drive into Pockethole
The K4 is the latest offering in the range of Pockethole Jigs from Kreg. It appears to fit a useful niche between the comprehensive, (and accordingly priced) K3, and the Kreg Mini Pockethole Jig, and provides the basic components that would be used for a vast majority of pockethole joinery jobs.
Kreg K4 Pockethole Jig
The thing that strikes you very quickly when using the Kreg, is just how easy it makes creating the necessary pocketholes. It is very simple to set the jig up to suit the thickness of the materials being joined, and only a few seconds are required to cut the pocketholes. As is provided with the K3 Master System, the K4 jig comes with an integral toggle clamp which is partly why the jig is so fast and convenient to use. Another aspect is the hardened steel drill bit guide, so the bit is accurately guided, hole after hole. When two holes are needed close together, the fact the jig has three guides in close proximity means that both holes can be drilled, without the need to reposition the jig itself.
Drillbit Guide and Toggle Clamp
Setting Guide Height to Suit Material Thickness
In some situations, it is not convenient, or possible to use the jig in its standard configuration, and so the drill guide can be removed and clamped directly to the workpiece.
I don’t use pockethole joinery in every project – because of the size of the elongated oval slot caused in the surface of the workpiece, I tend to use pocketholes in situations where this cannot be seen. There are fillers available, in a variety of timbers (and white plastic for melamine), and you could conceivably use a contrasting timber to produce a visual effect, but it wouldn’t be something you’d do often. On the other hand, it would be hard to find another joinery system more suitable for joining melamine, MDF and other materials that tend to have a very weak end-grain glued joint. This is particularly true for carcass construction for cabinetry, and building kitchen melamine (MDF or particleboard cored) cupboards.
Clamping Material Ready for Pockethole
Drilling the Pockethole(s)
The Kreg K4 System is an excellent investment for people who are not expecting to want to use pockethole joinery all the time (and therefore don’t want to invest in all the accessories), but want to be able to quickly and easily produce this sort of joint when the need arises. I will stress however, that just because you haven’t invested in the comprehensive kit, you haven’t compromised in the quality of the material or jig construction. This kit provides all the core components needed to start pocketholing in style.
90 degree Clamp
There are other accessories you can optionally get. I like this one – the 90 degree clamp. One side of the clamp has a normal swivel base, while the other side is a thin diameter, flat-bottomed point perfect for clamping into the pockethole itself, so you can put a screw into the other pockethole.
For joining boards together flat, there is the more standard Kreg clamp.
First Pockethole Screwed
There are various plugs designed to hide the pocketholes, including these for melamine. Others are different wooden dowels so you can either closely match colour to disguide the joining method, or contrasting timber to accentuate it. I still normally will design projects to hide the existance of the pocketholes.
It is perfect for picture frames, cabinetry (and on and on).
This pockethole jig (and accessories) were sourced from Carbatec, who carry a lot of the Kreg range. The K4 will be available in Australia in the very near future. I don’t have a price at this stage.
Filed under: Manufactures and Suppliers, Tools | Tagged: Cabinetry, Carbatec, Kreg, Melamine, Picture Frame, Pockethole | 6 Comments »