The mortise and tenon joint has been around woodworking and timber framing for hundreds of not thousands of years and continues to be a popular form of joinery. The joint can be both hidden or as it is described as "a through tenon" which often means the end protrude through the wood to expose the end of the tenon. Either way the tenon is a very strong joint and when combined with a good quality wood glue, in strength tests with many woods, the wood around the joint will fail before the joint fails.
The disadvantage of the joint is that it does take time to make and often takes some finessing to get a good quality joint, still, the mortise and tenon joint is one of mainstays of woodworking. Like many things in woodworking, pratice are repetition are the key elements of make good quality mortise and tenon joints, and this jig will give you a good head start on making the the tenon part of the joint.
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For our project today we are making a pretty simple jig that is accurate and easy to use and will give accurate joints without strenuous setup.
The jig only requires 4 pieces of wood, the main upright piece, which I recommend in and MDF or similar component as it is flat and retains it's shape and I made mine 10 inches wide by a 16 inches high. The wood components that fit around the fence. For these it's best work with wood that will slide on top of the fence and use the second piece as the adjustable part using hanger bolts with wing nuts in the event the wood swells or shrinks and the jig can be re-positioned around the fence for nice snug fit. The block of wood stabilizer that is attached to the upright needs to be substantially thick enough that when the wood being cut is re-positioned to cut the sides, the stabilizer is thick enough to hold the wood. I made mine about 2 inches side and 1-3/4 inches deep and about as 15 inches long.
I found that setting up the backer board with the topper board and pre-drilling the holes for the hanger bolts was the easiest approach. The topper board could then be flipped over and attached to the main upright board and thus the main components are assembled and ready to use.
The final piece is to attach the stabilizer piece which is easily done using a large square and a clamp. The lower part can be attached when the jig is in it's main assembly then the final screw can be inserted in the top when it is in place on the table saw. This will ensure the stabilizer board is absolutely vertical to the table saw's base.
The jig is surprisingly easy to set up and use, but really lends it'self to using measuring or set-up blocks and the blade height jig I made sometime back was also very useful, so if you are one of those woodworkers who enjoy creating mortise and tenon joints, or you would like to try it out, this quick and esay jig is a great place to start.
Copyright Colin Knecht