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Cutting tenons using power tools

There are a number of techniques, in part depending on the power tools you have available. Some require the use of a sliding table saw, but the first was used for many years before I had a slider, on a traditional (even cheap) regular table saw.

Definitions: The faces of the tenon are the four flat sides of the smaller part, normally edge grain. The shoulders of the tenon are where the faces ends, at the work piece, normally end grain. The shoulders need to be pretty, since they are the part that shows.

Method 1

When I had my regular table saw, I made a tenon jig that slid over the rip fence... it worked very well and had a lot of use. Many people copied it. see www.plesums.com/wood/tips/tenonjig.html Press backspace on your keyboard or previous page on your browser to return here.

That jig cut the 4 faces of the tenon; I just cut the shoulders with the table saw in the normal position, using the rip fence to determine the length of the tenon. (For safety, be sure the work is beyond the fence before it hits the blade, using a shim if necessary to space the work away from the fence, so the work is only supported by either the rip fence or the miter gauge, not both, when it is in the blade.)

Method 2

When I got my slider, I figured I would do it the same way, but my rip fence was not suitable for something sliding over it, so I built an "L" shaped jig (with a block of construction lumber holding the two pieces at a right angle). I clamp the jig to the slider with the hold-down clamps that came with the slider, and aligned against the smaller cross cut fence.

You can see a small vertical alignment fence on the leading edge, behind the blade in this picture. Some people prefer the fence on the trailing edge so the jig is pushing the workpiece rather than the workpiece pushing the jig and slider. Small pieces can be held by hand, or can be clamped to the jig. It worked, but has rarely been used. Someday I will just discard it.

Method 3

Occasionally I cut a tenon using the tablesaw to first cut the shoulders, then the bandsaw to cut the faces. I have a super bandsaw that I use for resawing, so I get pretty good tenons without a lot of fussing - not mirror smooth, but almost ready to glue. These tenons have square corners, my mortiser leaves round ends. I have found it easier to chisel out the mortises than to manually round the tenons (but that may be related to my lack of carving skills).

Method 4

My combo has a slot mortiser, so cutting a mortise is very quick and simple. Therefore I usually cut two mortises and use a floating tenon. Some people fear that it won't be as strong as a regular tenon, but using a table example, the mortise in the apron is about half the thickness of the apron, but the floating tenon fills the mortise, and is face glued to the inside of the mortise, so is at least as strong as the original wood. I have never had a problem.

I cut the floating tenons from scrap stock, and plane them to the thickness of my mortising bits, so I often have 10-20 feet of tenon stock in various widths, and thicknesses to match the most used cutters.

The weakness of this option is that you bring the work to the machine, and my slot mortiser is about 3 feet from the wall, so I cannot cut a mortise in the end of an apron longer than 3 feet (unless I move my machine which weighs 2,200 pounds - it isn't going to be moved just to cut a mortise). That is when I revert to method 3.

Method 5

The Festool Domino is a slot mortiser where you bring the machine to the work, rather than the work to the machine. The smaller one is ample for furniture use, and costs about the same as the slot mortiser option on the combo. If I were starting over, I would seriously consider a Domino rather than the fixed slot mortiser.

Method 6

The safety rules in Europe prohibit non-through cuts with a table saw. Therefore the classical European answer is that tenons are cut on the shaper. To get a tenon that is, for example 1½ inches long (40 mm), on a shaper with a 1¼ inch (30mm) shaft, your cutter will be at least 5-6 inches in diameter (150 mm). More realistically, a recent forum discussion involved two cutters, 16 pounds each, 220 mm (almost 9 inches) in diameter; and was discussing cutters as large as 250-290mm in diameter.

Those are scary large cutters. Removing that much wood will try to pull your work piece into the cutter, so a special tenon fence on the shaper is used that normally includes a bar across the full width of the tenon (no gap in the fence at the tenon - the cutters go above and below the bar. And a super strong hold down - MiniMax has an optional bar that attaches to the slider to support the work close to the cutter. This may be safer than a saw, but requires very expensive, heavy, professional equipment and skill - not for the audience I expect on this site. Cutting a rabbet 10mm (3/8") deep on the shaper is as scary as I want to get with that type of cut.