For October we are continuing our series on woodworking joints. This month we are featuring lap joints and miter joints. Lap joints are really a large group of joints in which one side laps over the other. A cross-lap joint joins two pieces with flush faces. The pieces may cross at any angle. Cutting dadoes of equal width and depth on the two pieces so that the face surfaces are flush when they are assembled makes the joint.
The edge cross-lap is very similar to it and is commonly used in making egg crate or grid designs. In the middle lap or “T” lap, the end of one piece joins the middle of the other. In this joint a dadoe is cut on one piece and a rabbet is cut on the other.
edge cross lap
middle or T lap
The dovetail lap joint is similar to the middle lap except that it is a locking type joint. You will find this joint on our plan #228 Noah’s Highchair. We used to lock the legs in place. The end lap is made by cutting a rabbet at the ends of both pieces, which usually join at right angles. This joint is used in making simple frames. You will find that most lap joints are cut with a dadoe head on a radial arm saw or you can use your table saw. A router table takes too long to set up and you will need to make multiple passes.
dovetail
lap 
end lap
Miter joints can be of the weakest joint that you can make. As it usually joins the end grain of both pieces. They are normally used for frame and case construction and are made to from right angle joints. This joint is very weak unless it is strengthen with a spline, biscuit, key or dowels.
A simple miter can be flat or on edge. Both types can be strengthened with dowels or splines. If a spline is used it can run either the full length of the groove or only part way across it.
flat miter with spline 
edge miter with spline
flat miter with key or feather
The woodworking season has begun and it is important that you exercise care and safety in your shop. After a full summer of kids, vacations and having a great time we can become a bit careless in our techniques and procedures. So take good care of your fingers and enjoy all your projects!
Brian Murphy
American Furniture Design Co