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Wedge is the secret to perfect angled mortise-and-tenon joints

comments (15) December 19th, 2013 in blogs, videos

MKenney Matthew Kenney, special projects editor
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Travelling man. This is the tool cabinet that Im making to carry and store my tools when I travel to teach and demonstrate. It breaks down into three pieces.
Angled legs. The back legs come out on a slant to provide more stability. The base is joined with mortise-and-tenon joinery, which means that either the back leg mortises or the tenons going into them must be angled. I chose to angle the mortises.
Step 1: Make a wedge. The slope needs to match the back legs angle. And make sure that the straight edge and end are square to one another.
Step 2: Set up the miter gauge. The sloped side of the wedge goes against the miter gauge, and the end of the wedge is flush to the saw plate.
Step 3: Cross cut the legs and stretchers. They all get cut at the same angle. The top and bottom ends of the legs are parallel to one another.
Step 4: Mortise the legs. Clamp the wedge to the fence, and slide the leg down the mortise. This accomplishes two things. First, you can use the machines depth stop for each cut, ensuring that the mortise is the correct depth across its width, which wouldnt happen if you moved the wedge, too. Second, by sliding the leg down the wedge, there is always material for the top side of the bit to grab.
Flip the wedge and leg to center the mortise. If you only flip the leg, then the chisel will mortise at the wrong angle. (This is optional, but I like a centered mortise, because it makes it easier to cut the tenon.)
Step 5: Cut the tenon cheeks. A dado set makes quick work of them. The angled end grain should be flush against the rip fence when you cut the shoulder.
Step 6a: Cut the edge cheeks at the bandsaw. This cut is parallel to stretchers edges, so there is no special set up needed.
Step 6b: Cut the top and bottom shoulders. These are parallel to the end grain, so register the stretchers end flush to the fence and carefully guide it through the blade. Leave a bit of waste and then pare it flush to the other shoulders.
Ready for assembly. The wedge took all of the guess work out cutting the joint, and you can easily get a fit joint straight from the machines.
No gaps. This is what its all about. The joint comes together tight and strong.
Travelling man. This is the tool cabinet that Im making to carry and store my tools when I travel to teach and demonstrate. It breaks down into three pieces. - CLICK TO ENLARGE

Travelling man. This is the tool cabinet that I'm making to carry and store my tools when I travel to teach and demonstrate. It breaks down into three pieces.

Photo: Matt Kenney

I don't travel with my tools very often (three or four times a year), but it doesn't matter. Packing up your tools so that they don't get damaged en route is a pain. In the past, I would wrap up my planes in towels, sheets of packing foam, whatever. Then I'd put them in a cavernous, plastic tool box. Chisels and layout tools went in there, too. It was a jumbled mess. And once I got to my destination, it was still a pain, because tools where hard to find, keep track of, and I was always worried that when I packed up everything for the trip home, I'd leave some beloved tool behind.

So, I knew I needed a travelling tool case that keep them safe and orderly. This is my solution. It's three parts: the legs, the big box (a plane till), and the small box (there are drawers in there for chisels, layout tools, etc.). I'll write another blog when I've completed everything, but I wanted to share the technique I used to make the mortise-and-tenon joinery for the base. In particular, how I cut the angled mortises and the angled shoulders on the tenons. The trick was a wedge that I used to set up my miter gauge, and to angle the legs when I mortised them with a hollow chisel mortiser. Because I used the same wedge for both, the tenon shoulders were a perfect match for the angled mortise. The photos above show how I did it, step by step.

posted in: blogs, videos, Tablesaw, safety, kickback

Comments (15)

William_Lohr William_Lohr writes: Any chance of getting some photos of the interior? Thanks.
Posted: 7:54 pm on January 4th

JimInNM JimInNM writes: Life is just easier if you're smart enough to figure this stuff out..
Posted: 11:49 am on December 13th

MacGregorWoodWorks MacGregorWoodWorks writes: How about showing the start to finish in an issue of FWW? I like the project!!!
Posted: 2:59 am on January 2nd

lhotta lhotta writes: Matt -
I am building two chairs using the project plans for the arts and crafts side chair by Kevin Rodel. The stretchers connecting the back legs to the front legs are 85.5 degrees. What I have done on my prototype is to modify a router box so that the supports are at 85.5 degrees. It seems to work OK, but always looking for ways to improve accuracy.

Posted: 4:10 pm on December 31st

Sanawwer Sanawwer writes: Hi

Found this post very helpful in organizing my tool chest. Thanks for the tips in managing a loaded tool chest.

Posted: 7:53 am on December 31st

Gordon_Dennison Gordon_Dennison writes: lhotta

Take a look at "chair making simplified" by Garrett Hack.
He makes a clamping jig for a router based around a series of wedges cut to different angles for routing mortices in chair legs.
I used the same idea for my mortice machine, you have to get a little creative when supporting the legs sometimes as were not talking bog standard joinery here, were working with curved parts that need mortices angled to different degrees. The simple answer is yes you can.

I copied this chair but used loose tenons so I cut the mortice into the stretchers as well, again you need to get creative with your wedges and supports, but that's the joy and challenge of being a woodworker. Its all about problem solving and pushing ourselves.

Good enough is not good enough - its just a beginning!
Posted: 2:11 pm on December 30th

MKenney MKenney writes: lhotta,

I'm sure this technique could be applied to the chair style you describe. I'd need to know more about the legs, stretchers, etc. to determine exactly how it should be done.

Posted: 9:12 am on December 23rd

MKenney MKenney writes: I'll absolutely post photos of the interior when I'm done--in January. We'll probably do a video tour of it.
Posted: 9:10 am on December 23rd

MKenney MKenney writes: Gbrookman:

That's right. Because the cut in step 5 isn't a through cut you can use the miter gauge and rip fence together. Also, I'm using a dado set, which is turning the waste into dust. There is no offcut to get trapped.

Posted: 9:09 am on December 23rd

ukmeager ukmeager writes: Looks good would have liked to see the interiors loaded
Did you put straps on the rear so you could carry it like a haversack
Posted: 5:27 am on December 22nd

GBrookman GBrookman writes: In step #5 you're using a miter gauge with a rip fence. I've always read that this is dangerous and asking for kick back. Is it OK because it's not a through cut?
Posted: 4:01 pm on December 21st

BeaverBoy BeaverBoy writes: This is elegant in its simplicity, useful, short, clear and to the point. Exactly what I hope for from Fine Woodworking. Thank you!

Posted: 12:15 pm on December 21st

lhotta lhotta writes: Sound geometry for legs that are parallel front to back.

Is there a similar setup for legs that are angled for a chair where the front legs are wider than the back legs?

(as seen from above)
/ \

Posted: 9:24 am on December 21st

graydane graydane writes: Ditto!
Posted: 8:44 am on December 21st

308defense 308defense writes: Hi:
I would love to see the inside of your two tool chest and how the tools are laied out.
Thank You
Posted: 4:14 pm on December 20th

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