Box joints were used to join pieces of wood together to make boxes, before plastic and cardboard were invented. Boxes put together in this way were normally used to store fruits and vegetables. It was, in fact, the cheapest method because there was a large amount of pine available, hence making it very cheap. At first manufactures used dovetail joint but than realized that box joints are far cheaper and less time consuming. So a box joint is simply made up of straight wood finger slots opposing each other and interlace at a 90 degree angle.
Step 1 - Preparing Your Wood
The first thing to do is to have 2 pieces of wood to make a box joint. If you intend to make a drawer you will need four pieces of wood which should be previously sanded. Obviously, the size of the pieces of wood depends on you and your project.
Step 2 - Wear Protective Gear
Before starting off, its a good idea to wear your protective gear, such as gloves, protection glasses etc. Next you need to set the DADO width to 1/32 of an inch higher than the thickness of the pieces of wood.
Step 3 - Using the Saw
This is a bit tricky but not hard to do. First mark the center of the board you are using and then attach it to the miter gauge. Place it in such a way that the center of the board and the center of the DADO stack point line up with each other. Run the board once through the dado before turning off the saw. Cut the second time with the help of the miter gauge as far as the first cut.
Step 4 - Milling
Mill a small piece of hardwood the same width and height of the dado and cut it into a 6 inch piece. The length depends on the project at hand. Insert the 6 inch key into the first dado slot and turn it on. Move it in a forward direction so that there is only an inch visible on the back of the gauge extension. Finally attach a countersunk screw from the bottom.
Step 5 - Using the Miter Gauge
Now use the miter gauge and slip it into way and remember to keep the extension fixed in its place so that you can align the second dado slot. Once you have aligned it you can attach the extension back on the gauge.
Step 6 - Marking Your Boards
Now mark one wood board A and the other B. Ram with the key one of the two boards over the dado. Run the latter again with another dado. The result will be boards A and B which are well milled and cut at the same length in order to join accurately.
Step 7 - Pass Your Boards Through the Miter Gauge
Grab board A and place it backwards on the miter gauge. Put board B against the other board (that is A) so that the edge is lined with the edge of the dado stack. After running the dado, simply relocate B so that the first dado is now on the key and run the dado after removing A.
Step 8 - Test the Box Joints
The last step is to test the box joint and see that all fingers fit perfectly so that then you can apply the carpenters glue to fix them together. If you’d like you can use some pin nails to reinforce the joint.