For building things out of wood, the mortise and tenon is the strongest woodworking joint while the butt joint is the weakest. Unfortunately, the mortise and tenon is difficult to get right even for professionals, and has stopped more than one amateur woodworking project before it even got off the ground. Fortunately, humans are inventive creatures. Just like inserting iron or steel rods into concrete greatly strengthens the entire system, the same goes for inserting a screw into the simple butt joint. The simplest method is called the screwed butt joint, while a stronger and more complex variation is called pocket hole joinery. Until the late 1980s, pocket hole joinery was as difficult to do as the mortise and tenon while not being stronger. But that changed with the invention of the Kreg jig.

The Kreg jig has made pocket hole joinery simple even for novice and casual woodworkers. It has also enabled professional woodworkers to greatly increase their productivity. And after twenty years, for those who do not think the Kreg jig is worth its price, there are quite a few cheaper knock-offs and third-party parts.

So which is stronger - the mortise and tenon or the pocket hole joint? With modern glues and modern screws, it does not make a difference in practice. Woodworkers and carpenters with too much time on their hands have compared both joints by sticking random pieces of wood together and bashing them to pieces. In most tests, the pieces of wood broke apart before the joints did, regardless of how those joints were formed. Since using a Kreg jig (or any of its clones) makes pocket hole joinery so much easier and faster than the mortise and tenon, there is no longer any reason not to do it.

This means that a professional carpenter, to whom time is money, has no reason to continue using the mortise and tenon now that the Kreg jig has made pocket hole joinery such a quick process. The same goes for any amateur carpenter who has been using the screwed butt joint up to now. There is no longer has a reason to stick with this weaker joint. They can use a Kreg jig to make a pocket hole joint as easily and quickly as their good old screwed butt joint. The only ones who may still want to use the mortise and tenon are master craftsmen who make premium furniture or reproduction antique furniture.

The Kreg jig, its clones and its pirated knock-offs also make furniture repair easy. In the past, when the joints of a chair or table or anything else made of wood started to become loose, you would hammer a nail in or screw the pieces together. This kind of impromptu repair work tends to be ugly and does not last as long as you hope it will. Drilling in the angled holes needed for pocket hole joinery on an already assembled piece of furniture is something not many carpenters could do. But now the Kreg jig allows even an amateur carpenter to make a clean repair to older creaking furniture.

So should every woodworker rush out to buy a Kreg jig, or should they hunt around for a cheap pirated clone? That depends on your experience in carpentry. For a casual DIY-er or novice, it is better to buy the original. The instruction manual has been fine-tuned over two decades and is very clearly written to teach you how to do pocket hole joinery correctly (with the Kreg jig). Fortunately, Kreg company has made a number of different models at different price points to suit every budget. The cheapest model is a single hole system that sells for around $20.

On the other hand, a seasoned professional would not need the instruction manual, and could buy a good Kreg jig secondhand at a steep discount to the list price of a new kit. Or he could choose to buy a good quality clone which uses cheaper generic screws for the pocket holes.

What you choose to do is up to you, but a Kreg jig (or some kind of cheaper knock-off) is an invaluable addition to any carpenter's kit. It is something that allows you to strongly join two pieces of wood together quickly and easily.