Tenons with a JIG

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When you need to cut a tenon with perfectly smooth cheeks (for example when making a bridle joint), the standard blade method is the answer. This technique separates the shoulder cuts and the cheek cuts into two operations.

First, the shoulders are cut with the workpiece flat on the saw table. Then, the workpiece is held upright in a tenoning jig to remove the waste from the cheeks (right photo). The jig makes control of the workpiece easier and results in more accurate cuts. I'll talk a little more about the tenoning jig when it's time to use it for the cheek cuts.

SHOULDERS FIRST

As I mentioned, the shoulder cuts come first. And there's a good reason for doing things in this order. The length of the tenon is determined by the shoulder cuts, and this dimension can easily be measured as the saw is set up and the cuts are being made. But to accurately judge the correct thickness of the tenon, you need to compare it to the mortise. You can only do this after the waste has been removed with both the shoulder cuts and the following cheek cuts.

THE SHOULDER SETUP. The table saw setup used to make the shoulder

Table Saw Fence Plans

cuts (long shoulders first) mirrors the setup used for the dado blade method, as you can see in Figure 1. The miter gauge with auxiliary fence attached and rip fence serve the same purpose as before. The difference, of course, is that you'll have a standard blade on the saw. (A combination blade works best.)

ADJUSTMENTS. Again, both the height of the blade and the position of the rip fence need to be set. Here, the blade height isn't quite as critical since the following cheek cuts determine the final thickness of the tenon. I simply sneak up on correct height with test cuts across the tip of the tenon.

Once the height of the blade is in the ballpark, you can zero in on the rip fence setting. This determines the length of the tenon, so here you want to be dead-on accurate.

THE CUTS. When the adjustments are completed, it's just one quick cut across each face (Figure 1). Keeping the workpiece snug and square to the fence and flat on the table is all you need to focus on.

SHORT SHOULDERS. The short shoulders can be cut with the same setup and in the same manner (Figure 2). But you may have to change the blade height before standing the piece on edge for the single cut. Again the key is to avoid cutting into the clean, long shoulders. Just don't force the workpiece too firmly against the fence, and this shouldn't be a problem.

First, Long Shoulders. After adjusting the blade height and the position of the rip fence, a cut across each face establishes the long shoulders.

Next, Short Shoulders. Stand the piece on edge to cut the two short shoulders. To do this, you may need to readjust the height of the blade.

First, Long Shoulders. After adjusting the blade height and the position of the rip fence, a cut across each face establishes the long shoulders.

Next, Short Shoulders. Stand the piece on edge to cut the two short shoulders. To do this, you may need to readjust the height of the blade.

USING THE JIG

With the shoulders cut, you're ready to put the tenoning jig to work cutting the cheeks and edges. There are many types of tenoning jigs, but the one I like to use, shown at right, has the dual advantage of being simple to build and easy to use. It's essentially a saddle that rides along the rip fence of your saw to carry the workpiece past the blade. A vertical fence holds the piece straight and square. And any adjustment to the cut is as easy as moving the rip fence.

THE CHEEKS CUTS. The cheek cuts come first, then the edge cuts. You start with a simple adjustment of the blade height. Just stand the workpiece beside the blade and let the shoulder cut act as your reference line while raising the blade. You want the blade to cut a hair below the shoulder line.

Next, you'll position the rip fence. This will determine the thickness of the tenon, so getting this adjustment right is pretty important.

As you see in Figure 1, the fence is positioned so that the cutoff waste can fall free and not be trapped between the jig and blade. You'll make one cheek cut and then flip the piece side-for-side in the jig to cut the opposite face.

To position the fence, I clamp a workpiece in place and start by setting it intentionally wide. Then I make a pair of cuts and compare the tenon to the mortise. This shows me how much to move the fence for another trial. I always like

Table Saw Router Workbench

Workpiece

NOTE: All jig parts are plywood, fence is hardwood

NOTE: Fence is seated in perpendicular dado

Workpiece

NOTE: Size jig to fit rip fence

NOTE: All jig parts are plywood, fence is hardwood to take it slow and gradually sneak up on a good, snug fit.

When the fence setting is dead-on, you can cut all the cheeks — one side, then the other. The jig really does the work. All you have to do is make sure the workpiece is snug to the table and clamped securely. Then push it through the blade.

TOP AND BOTTOM EDGES. The final step is to size the width of the tenon by cutting the top and bottom edges. This is also done with the piece clamped on end in the jig, but turned 90°, as in Figure 2.

Like the cheeks, the waste is cut away to the "outside" of the blade. But first, you'll have to readjust the fence to size the tenon accurately. And here, you can simply test fit the width of the tenon directly to the mortise. Just a little firm pressure should seat the tenon.

So you have two good choices. Either technique will give you great results. And when you need to go the extra mile, the box below offers a few tenon fine-tuning tips. ES

NOTE: Fence is seated in perpendicular dado

NOTE: Size jig to fit rip fence

Cheek Cuts. The workpiece is clamped securely in the jig. Make sure the waste falls to the outside.
Trim To Width. Again, with the workpiece in the jig, trim the tenon to width with a cut across each edge.

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