This week I’m working on a small Arts & Crafts project coming out in a week or two. One of the joints used in the project is what I call an egg-crate joint as shown in the opening photo. Some woodworkers call this joint a half-lap because you’re slipping half of each board together. Years ago I called a ship-lap joint a half-lap for the same reason. Regardless of what you call this slipped-together connection, I thought I’d share how I tweak the fit when using a table saw.
Attach a sacrificial fence to your miter gauge so that a portion of the scrap extends beyond the blade by a few inches – it also needs to be taller than your cut by a couple of inches. Set your tablesaw blade height to half of the overall width of the two boards you’re joining – in my case one of the pieces becomes a handle so it’s wider than the other, but the joint itself is half the width of the non-handled piece.
With the layout work done on your parts (if you want to see how I do that work, you’ll need to become a paid member of 360 WoodWorking), align the inside edge of your mark with one side of your blade and make a cut. I then align the second mark with the opposite side of the blade, again on the inside edge of the mark, and make cut #2. Working this way guarantees that you’ll not make the opening wider than the piece you’re trying to fit, unless your layout work is incorrect. If you need to, clean out any remaining waste with another pass over the blade.
If I need to tweak the opening so that two pieces fit, I slide the part back over the blade, turn on the saw then move the work piece to one side until it just kisses the blade. As I make a complete pass, the joint usually opens just a hair. If the fit is still too tight, I repeat the action and push the second side of the slot against the blade and make another pass. Moving side to side helps keep the slot centered in the board.
You may have a different method to create this joint. And you may have a different name for the joint. If you do, what do you call it?