Mortise and Tenon Joints

[workingwood]

I have been doing most my wood working with mechanical fasteners or biscuits. How ever I would like to expand my wood working skills to use more mortise and tenon joints. My question on this is there a mathematical rule of say 50% less the thickness of the board is what the mortise and tenon should be? or is it in standard sizes like 1/4" /12" 3/4" etc...

As an edit to my post I would also like to know if the same type thing applies to the depth of a mortise and length of a tenon? how are those determined?

 

[Joe Scharle]

General rule of thumb is; "Third and long".
1/4" into 3/4", as far as reasonable. Ex.: I would put 2 - 1" tenons (each 1.5" wide) on a 5" apron board, 1.5" into a 2.5" leg if I were to make the aprons flush with the leg's outer edge. However, I like a 1/8" reveal or shadow edge, where the apron meets the leg. So, since 2 sets of apron tenons are entering the leg at right angles, the farther I make the mortises from the outside edge of the leg, the shorter the tenons must be.

Since you are just starting out on M&T joinery, I suggest that you begin with 'floating' tenons. Personally, I prefer floating tenons to the traditional integral tenons.

 

[workingwood]

Thanks for the response. I will the difference between them are. My thoughts were to start off with mortise and tenon with a hole drilled through and a dowel for some of the projects I want to build. Part of my goal over the course of the next year is to increase my wood working skills by using non-mechanical fasteners as well as get better at my box joints and dovetailing so I have more of a flexibility to build things without necessarily relying on mechanical or metal fasteners.

 

[LeftyTom]

Joe probably gave the correct answer.

I use floating tenons (Beadlock), with the thickness of the tenon being 1/2 the thickness of the board (not leg) that I am using.

I'll leave about 1/8" at the top and bottom shoulders of the tenon.

 

[bluedawg76]

In addition to Joe's sage advice, Bill Hylton has a nice book "Illustrated Cabinet Making" that details many variations of common woodworking joints that I'd highly recommend. It's probably available at your local library.

As always, there are more ways to make M/T joints than skin a cat:
mortise: chisel, router, drill press, mortiser, laser?
tenon: handsaw, router?, tenoning jig on the TS, dado stack on the TS

And then the tweaking adjustments of the tenon -shoulder plane, router plane, rasp, chisel, laser?

Since you are just starting out on M&T joinery, I suggest that you begin with 'floating' tenons. Personally, I prefer floating tenons to the traditional integral tenons.

Now you tell me......:BangHead: Joe, do you have a preferred method for milling/prepping tenon stock? I've always used traditional M/T b/c I'd have to make a jig to mortise into the end of the board (aka the rail). Do you have a preferred jig/setup for this as well. Thanks in advance!

Sam

 

[Joe Scharle]

Yes Sam, I do. I have a Woodrat, which is a CNC where the operator is the computer. But, it was invented in 1982! And I also have a R/T jig that works pretty well. In fact, it got invented because I was afraid to break my Woodrat mortising setup as few years ago, and needed ONE MORE rail.

Woodrats/Router Bosses can be setup to cut most joints and are excellent for boring mortises; especially into end grain. They easily machine tenons and make box and dovetail joints as well. Here's a pic of mine...

And here's a pic of my R/T tenon making jig. Won tip of the year a few years ago.

 

[Mike Davis]

workingwood,

Do you want to increase production or increase your skills? If you depend on jigs, routers, CNC machines and the like you will make fine joints but never really increase your hand skills. You will increase your power tool collection though. And if that is what you want that is fine, many (most) woodworkers never pick up a mortice chisel or a back saw.

Some folks are moving towards less tools and more skill and finding satisfaction in making good joinery with simple hand tools and less power tools.

I'm somewhere in the middle, I use a tablesaw to rip boards and some crosscutting, a band saw for curved parts and re-sawing thick boards, a planer for reducing the thickness and sometimes a jointer to straighten the edge of a board. But, all my joints are cut with simple hand tools like chisels and hand saws. I am moving more and more toward final finishing with hand planes and card scrapers.

 

[Rick M]

Your goal is to increase your skills so start with mortise and tenons then move on to drawbore tenons, wedged tenons, etc.