First off since you are working on furniture…clean up your bench. Sweep it off and put the tools away. This may seem odd since you are going to take the tools out again but it’s not, you are going to pound on your work quite a bit during this process. Chips left on your bench get wedged under your work and dent it. Sweep your bench off and keep it clean. I put all my tools away after each joint is made to fit, this speeds things up because you are not fishing for tools you thought to put in one place or another, and it also helps make sure that you don’t knock a tool off of your cluttered bench onto the floor. If you knock a chisel off of your bench let it hit the floor…even if it is a $100 Ray Iles and it snaps on concrete (unlikely) it will be cheaper to replace it then go to the hospital for stitches.
The haunched mortice and tenon has a few differences from a standard mortice & tenon, but it is still a simple joint to work with.
The first major difference that you need to cut two mortices in each leg. I suggest that you pick a leg, and drive the two mortices into that leg, then cut the matching tenons for those mortices. Repeat this order on the other 3 legs.
As to the actual driving and cutting of the joints here is the best way to go about it:
1. Set your chisel to a depth that just licks the interior side of the second mortice that you will cut. (masking tape helps) This is fairly easy to figure out since you can see the final depth from the outside of the joint.
2. Cut out the partial depth mortice, leaving the haunch alone. Check for depth with a square and check that your chisel is vertical often by placing a short ruler against the true face…you should be able to see that the ruler and your chisel are parallel.
3. cut the haunch using a new depth mark, My bevel happened to be just right so I did not need a second piece of tape. Be careful here…I drive the chisel to depth and come back from the mortice side to get under the chips and lift them out, this makes the interior of the joint a bit cleaner. I cut my haunch a tiny bit higher than the table height line (Robert wearing goes all the way to the end), this allows for some adjustment in the assembly.
4. Cut your full depth mortice on the other side (and the haunch too). The joints should meet, barely. By cutting the first mortice at partial depth you allow the second one to be cut while fully supported…this prevents breakout on the interior of the joint and saves valuable glue surface.
5. Cut the second haunch.
Now find the rails that would mate to the two mortices you cut. I like to keep the leg I am working on and one of the rails I am working on atop my bench while I work. The other parts I tend to keep on my saw bench. There are several ways to cut the tenon, I played around with the order quite a bit on a few that I have cut so far to see what works best and I can say that this is the order I think is the most efficient and clean.
1. Cut the cheeks. This is the most critical part of the joint since it contains the long grain to long grain surfaces of the joint (joints have two kinds of strength, glue and mechanical interlock…maximize both wherever you can).
2. Make the rip cuts for the, setback and haunch. Be especially careful on the setback not to cut too deeply, this would show on the outside of the joint.
3. make the cross cut for the haunch.
4. chisel a v groove into the shoulders. Crosscut those (this includes the crosscut for the setback). Take care with your saw not to over cut the joint. You may have to break of the cheek waste piece since the cuts are sometimes made in an arcing motion leaving a hump in the middle of the cut…you will pare this out with a chisel later.
5. First test fit. If you are like me your joint length will not be perfectly designed and will most likely be a hair overlong (short happens too but is less common and should be avoided since it gives you less glue surface). The goal here is to get the joint to bottom out on the interior wall of the mortice (you can see this quite clearly if your mortices meet like they should). Once you hit bottom you should see that the shoulder has a pronounced gap to get to the leg. Measure this gap with playing cards and add one card to the deck, transfer the thickness of the playing cards to your marking gauge and scribe around the end of the tenon. Remove this this from the end of the tenon with a saw (if larger than 1/8th) or a chisel (if smaller than an 8th). Keep the gauge setting since it should be the same for all the joints. Playing cards are handy…the extra card we added gives just enough clearance for the glue to go somewhere.
6. Second test fit. Assemble the joint making sure that the shoulders meet the leg. From the open mortice, scribe a line on the tenon with a chisel. Use the wall of the mortice that is closest to your rail shoulder (the inside of the table) to guide the chisel.
7. With this line you can use a chisel to miter the inside face of the mortice…get the scribe line and the back corner to meet and then take a bit more off the miter to avoid the two miters bottoming each other out. This is great practice with a chisel…your results don’t have to be pretty, but aim for it anyway so you can learn control.
8. Do the other tenon and test fit the leg with both rails in it at once.
Check for square on the joints often and early…Troubleshooting joints that are off is a pain but its worth taking the time to think out your adjustments before you make any cuts. If it takes more than a few tests to get everything fitting right that’s fine, take your time and don’t force things (my first tenon on this table made my bench look like a warzone FYI…the rest have fit pretty well from the saw). If the joint is fat in places when you try to assemble it you will see shiny spots where the grain gets compressed. Remove those lightly…I would rather take a lot of light cuts and get things right than remove to much and have to correct a sloppy fit.
Here is the video I shot for the process.
Cutting the mortices in the work.
Cutting the tenon took 3 videos.
-- Make furniture that lasts as long as the tree - Ryan