Mortise & Tenon joints - my way - your way

[Bernie LeBlanc]

The mortise and tenon (aka mt) is a great joint for looks and strength. But like all other joints, there are different methods to achieving your goal. First of all, let me describe my definition of a good mt joint. I invite discussion here or at any time or point of my post. A good mt joint needs to be dry assembled with no mallets or hammers involved. Once assembled, it needs to hold, meaning you can pick up the joining pieces in any configuration and the joint will hold. It also needs to be disassembled by hand - no hammer etc.

I have seen posts that suggests you make the tenon 1st, then the mortise, but most of us revers this method. Like most, I cut the mortise 1st and then I make my tenon a bit fat and I trim it down to fit.

Tools used to accomplish the mt vary... this is how I like to do my mt joints. Many folks use a mt machine and that's fine if you own a good machine. Unfortunately, I don't. My mt machine is cheap, for instance the depth gauge stop slips off the post bottom so I corrected the problem. But I do own a cheap machine and since I do not wish to bash specific tools, let me move on.

I basically use a doweling jig to hog out my mortise.

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This jig automatically finds the center bore on boards and insures me a 90* bore. I then square the mortise with my cheap mt machine. At this stage, a good chisel could finish the joint. I bought a very good tenon jig for my table saw and can precisely cut my tenon joint. My method works great for me and I'm sure other posters can differ with my method while achieving the same result. I would like to hear from you so others can find a method best suited for them.

[Stephen Cherry]

My mortise-tenon philosophy is tight on the ends, loose on the sides. Loose ends are a glue joint, and it's days are numbered right from the start. Tight sides can cause the leg to split.

Use whatever you have to cut the tenon cheeks, but cut both at the same time. Two blades spaced on a table saw with a tenoning jig, or if you have it, a shaper with tenoning disks. Outside of the part towards the shaper table or tenoning jig. THE SPACING IS SET TO MATCH THE MORTISING TOOL!!! ! The bottom is not trimmed, the top is cut down with an inca table saw, and a sharp chisel.

When the tenon is cut, the top of the mortise length is transfered to the part by laying the tenon on, and marking with a chisel. I use a hollow chisel mortiser for the hole, but a router and sharp chisel would work as well.

[Jim Matthews]

My mortise-tenon philosophy is tight on the ends, loose on the sides. Loose ends are a glue joint, and it's days are numbered right from the start. Tight sides can cause the leg to split.

?

I was taught that the long grain surfaces are the strength in the glue joint.
Loose "cheeks" mean a compromised bond. The seasonal movement of wood is cross grain, mostly.

That's the haunched part of most tenons, in any case.

The bottom of a mortise is mostly endgrain and there's virtually no glue bond there.

On fitting, M&T joints, if you need to drive the joints together with a mallet, it's too tight.
Once assembled, if you pickup the tenoned piece and it should all stay together without glue.

http://web.hypersurf.com/~charlie2/MT/MTPrimer13.html

[Mike Henderson]

Your technique of mortise first and then tenon to fit is the one that most people use. After all, that's why they make all those tools to trim tenons.:)

Many people, myself included, drill out the mortise and then clean it up with a bench chisel. Often, I drill with my drill press, but your idea of the dowel jig is very good for those times when you can't, or don't want to, use the drill press.

Regarding fit, I'm with Jim, above. I make the joint tight enough to hold together without glue during a test fit.

I don't understand Stephen's post, above, but perhaps he didn't express himself as clearly as he wanted to - or maybe I just don't understand. I would think that you want the faces of the tenon to be "tight" to the mortise because that's where your long-grain-to-long-grain gluing surface is - and that's the strength of the joint. I make the mortise a bit deeper than the tenon is long for two reasons: (1) you don't want to be surprised and find out the joint won't go together, and (2) it provides space for any excess glue. I sometimes make the mortise a bit longer than the tenon is wide so that I can make minor position adjustments during glue-up (but not much space).

I cut my tenons one side at a time. Can't think of any reasons why that would cause any problems, and never had any problems.

Mike

[glenn bradley]

My m&t's are seldom centered but, I frequently work in irregular dimensions. Centered or not I am in the mortise first, fit the tenon to it, camp. No mallet required. If you need a mallet during dry fit, there is not enough room for the glue. If the dry-fit joint falls apart, there is too much room for the glue. Not so much a science as a precision. One nice thing about fitting the tenon to the mortise . . . if you trim too much of the tenon and get a sloppy fit, laminate a piece on the surface you overshot and go at it again. I find equal success with blind, housed, floating, wedged, pinned, tusked and through tenons and use them as the design calls for. A wonderfully versatile, long lasting, rack resistant joint. Tenons, there not just for aprons anymore :D

[Thomas Hotchkin]

Bernie
I use this.Tom

https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcThVtWAhMR2H9x3mjGk8zTRoz6JUCosD l-LpZ5CKM8r0JDJAXGv

[Charlie Jones]

I use this.

Charlie255657

[Stephen Cherry]

?

I was taught that the long grain surfaces are the strength in the glue joint.
Loose "cheeks" mean a compromised bond. The seasonal movement of wood is cross grain, mostly.

That's the haunched part of most tenons, in any case.

The bottom of a mortise is mostly endgrain and there's virtually no glue bond there.

On fitting, M&T joints, if you need to drive the joints together with a mallet, it's too tight.
Once assembled, if you pickup the tenoned piece and it should all stay together without glue.

http://web.hypersurf.com/~charlie2/MT/MTPrimer13.html (http://web.hypersurf.com/%7Echarlie2/MT/MTPrimer13.html)

Oops- by loose I mean that you can slide it in and out, but there is not a lot of clearance. Basically, I can slide in a corner of the tenon into the hole and out of the hole pretty easily, But the ends of the tenon can be tight in the hole because it won't open up the joint. If you cut both sides of the tenon at the same time to match your mortising tool, it's possible to get the dimension consistently right, without using the shoulder plane. If you need to use some taps with a mallot to put the whole tenon into the hole, this is great because if you have the side dimensions right, you know that you are not going to split the leg because the force is on the top and bottom of the joint (as in a wedged tenon).

Here's the tooling I use:

http://www.sawmillcreek.org/showthread.php?152312-Hollow-Chisel-Gloat

http://www.sawmillcreek.org/showthread.php?156365-Tenoning-with-the-shaper

[John TenEyck]

And I use this. It cuts tenons, too, but normally I use loose tenons as they are a lot faster and the fit is automatic.

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[Rod Sheridan]

Hi, I use a hollow chisel mortiser for the mortise, and a shaper for the tenon.......Rod

[Jim Matthews]

I make maybe a dozen M&T joints in a year.

From the industrial appliances shown in Stephen's link, I gather he makes considerably more of them.
There's considerable difference in the approach to making one or two versus building a run of doors for kitchens.

I, for one, would only use something the size of Stephen's shaper to deal with downed tree branches from our last storm;
that thing looks like it could shred a mile of guardrail...

[David Winer]

Impressive.

[Stephen Cherry]

There's considerable difference in the approach to making one or two versus building a run of doors for kitchens.

.

In my opinion there does not need to be. It seems that the objective it to cut the joint accurately, so that it does not need to fine tuned too much. (even a table has 8 joints, so faster is better). A table saw with two blades spaced apart (as in the Tage Frid book??) will cut both sides at once, and the precision is in the setup. Get it right once to match your mortise tool, and save it for next time.

OR a normal tenoning sled on the table saw with an appropriate shim equal to the mortise width plus the saw blade kurf (I think). Board face towards the sled, make one cut with and without the shim between the board and sled. The tenon thickness is "remembered" by the shim. Same for the bandsaw.

[Shawn Pixley]

I do a lot of M&T's. I do the by hand, Hollow chisel mortiser, and domino. Many of these are situations where the mortise may not be centered on the stock for aesthetic or functional reasons. For the tenons, I cut many on the tablesaw (mortising jig or dado blade) depending upon application. I tune and fit the tenon & shoulder using hand tools (router plane and / or shoulder plane). For some (curved shoulder for instance) I use only hand tools.

[pat warner]

"I would like to hear from you so others can find a method best suited for them. "
*****************************************
Routers for both sexes of the joint.
My fixturing, unique for the mortice (http://patwarner.com/images/morticing_jig.jpg) & tenon (http://patwarner.com/images/index_tenon.jpg), are continuously adjustable.
It matters not whether I mortice or tenon first. The opposing fixturing can always be tuned to the dimensionality of the other.

[Curtis Gray 1]

Hi, I use a hollow chisel mortiser for the mortise, and a shaper for the tenon.......Rod
Rod, would you please elaborate on the shaper set up for your tenons? I use a PM model 10 for mortises, and currently cut tennons on the table saw with a dado stack. Thanks.

Curtis

[Frank Drew]

The method I settled on was horizontal slot mortiser, and dado set on the table saw for the tenons. I'm intrigued by the idea of using a shaper for the tenons, but I never tried it (I never really thought of trying it, in truth).

[Jim Matthews]

I make mine with a ten dollar bevel edge chisel, nylon faced mallet and a backsaw.

Faster isn't one of my considerations, really.
Neither is spending a thousand dollars so I can make a joint...

[Stephen Cherry]

spending a thousand dollars so I can make a joint...

Have you heard of the festool Dominoid? Peolple love to spend money on those!

For me, I buy everything used, so if I had to, I could probably move on without loosing my shirt. Or, if I started with a long sleave shirt, I'd at least end up with a tank top!

[Mike Henderson]

Have you heard of the festool Dominoid? Peolple love to spend money on those!

For me, I buy everything used, so if I had to, I could probably move on without loosing my shirt. Or, if I started with a long sleave shirt, I'd at least end up with a tank top!
Yep, the Domino is an amazing machine. I was put off by the price but a buddy bought one and eventually he loaned it to me to try out. After using it on a project, I was hooked and bought one for myself. Now, I use it on almost every project. Some of the uses are for applications where I might have used a biscuit in the past. Other times, it's a loose tenon application. It's fast and accurate. Sometimes, I use it just to make a mortise and then make a traditional tenon. I think of it as a portable horizontal slot mortiser.

But it's fairly expensive. I wouldn't recommend buying it unless you do a fair number of projects a year and the projects are ones you'd use the Domino on.

Mike