Open ended mortise on the table saw
This little project started with a desire to have a safe place to store a bunch of spare 8-foot (2.4 meter) long fluorescent tubes in my big garage workshop.
That's a good reason to use better joinery.
I imagine the joint would have held a little better if I had used the Kreg washer head screws instead of drywall screws.
I'm going to cut the tenons using my table saw sled, with a plywood box on it.
The box is pinned down on the table saw sled with a block of wood that is clamped to the sled. A shim under the far end of the block causes it to rack a bit, exerting downward pressure on the inside the box, locking it in place.
The workpiece is clamped to the box and the tenons are cut. I flipped the workpiece to do the other side. I normally advise against flipping the workpiece, because any inaccuracy in the wood will translate into inaccuracy of the tenon. But I only had two joints to make.
There was about half a millimeter of waste left on the tenons. I broke these off by hand and cleaned up the edges with a utility knife. If the waste was a thicker, I would have trimmed it on the table saw.
Next I need to cut a strip of wood that is one blade thickness less than the thickness of the tenons. So I hold the tenon next to the fence, and set the fence such that the left side of the tenon is flush with the left edge of the blade.
If in doubt, err on the side of making the strip too thin. If you make the strip too thick, your mortises will be too wide.
An open ended mortise can also be called a "bridle joint", though a typical example of a bridle joint would join two pieces of wood with similar cross sections.
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