There are dozens of different ways to cut a tenon, from using a $10 handsaw to a two-headed tenon that costs thousands of dollars. But most of us home woodworkers choose something in between. We want precision, of course, and speed would be nice, but we don’t want to have to spend a lot of money or be limited to a small range of sizes.
No template is perfect for every type of tenon under the sun, but there are a few we can select for our consideration. These are my criteria for choosing a dowel jig.
1. Length of the spike.
Any jig that cuts the end of the dowel vertically, such as the Leigh Router Jig or the Delta Table Saw Jig, will have the machine’s depth of cut as a limiting factor. For a 10″ table saw, this means tenons up to 3″ long. On a router, it is the length of the exposed router cutter.
On a band saw there is no length limitation, just that the width of the workpiece is less than the height below the blade guard.
2. Thickness of the dowel
If you use a template that uses templates, then you are limited to the size of those templates. For new build projects that probably won’t be a problem, but may be if an older part is restored. Most people in North America use inches as their unit of measurement, while most of the rest of the world works in millimeters. Being able to use either system is sometimes very advantageous.
3. Accuracy and consistency
Consider the way the template actually works. Are both cuts on the cheeks referencing one face, just like you would with the hand, or are they referencing two different faces? The latter is common, where you have to rotate the workpiece to cut the second cheek, but this is inherently inaccurate. If your workpieces are a slightly different thickness, then your tenons will be, too. Some will be tight and some will be loose and will require a lot of adjustment to get right. Also, the tang will always be dead center whether you want it to or not.
4. Safety of the machine
Many dowel jigs, especially those designed for use on table saws, require the user to remove the riving blade because it is in the way. The splitting knife usually supports the blade guard, thus exposing the user to unnecessary risk. Be sure to choose a jig that allows for easy operation but maintains your personal safety.
5. Versatility
If the template you choose can be used for a variety of tasks in the shop, you’ll get an added benefit. For example, will it also cut flanges or joints in half, or perhaps keyed miters? Can it handle offset tangs or twin tangs, or is it a one trick pony?
6. Speed set-up
Almost all dowel jigs can be relied on to produce accurate dowels, but how easy are they to set? Some templates take longer to set up than to use for a batch job. It is not only the fit of the shank that must be taken into account, but also its position within the thickness of the workpiece. This is especially important when framing faces. If the dowel is not in the right place, the fabricator will have to plane the faces of all the rails and the backs of all the studs to get it all flush. On some jigs, moving the dowel more, say, 1/32″ requires repositioning both faces of the dowel separately, so both adjustment and positioning become a matter of trial and error.
7. Speed in use
Once the jig is set up, how fast does it cut the tenons? A jig that cuts through the cheeks and shoulders in one cut, rather than nibbling off 1/8″ at a time, will be quicker to use.
Once you’ve satisfied yourself with the dowel jig problems above and found one that ticks all the boxes for you, you need to decide whether to buy one off the shelf or build your own.
There are many plans online, some free, some not, but most of them, at least in my opinion, fall short, especially in the departments of speed of setup and security in use.
And many of those available on the market have serious capacity limitations, as well as the configuration and security issues of most others.
With speed, safety, precision, and versatility in mind, I developed the Ultimate Tablesaw Tenon Jig and, later, the Ultimate Bandsaw Tenon Jig. There’s no bare table saw blade to risk your fingers on and both jigs are quick to set up and use. Also, I’m not restricted to having the tenon dead center, I can make it match the mortise if it’s not dead center, and if the tenon isn’t quite in the right place, I can move the entire jig precisely and accurate. just enough to get it to line up properly and to do so without losing the tang fit in the process.
I also found it easy to use for twin tangs and half split joints, so it ticks all the boxes for me and others have said they would never go back to their old cast iron model. Sure, buying one is quick, but making your own as a project in its own right is very satisfying, especially when the end result is so much better.
It looks complex when you first see it, but each part has a particular function and it’s pretty simple itself. If you find it too daunting, start by making one of the many free designs available on the net. But see if you can improve on the original design, keeping in mind some of the issues raised above.
So however you decide to cut your tenons, make sure your jig cuts them right the first time every time.
Happy woodworking!