Thursday, May 10, 2012

Mortise & Tenon -- Hybrid Tutorial

     The project I was working on for my wife was a fairly straight forward frame for a bulletin board she needed in her studio.  For bulletin boards I like to use those 3/4" thick styrofoam sheets you can buy at the local big box store.  They're also great for packing materials but that's another story.  So, what we have is 5/4 Poplar for an approximate 30" square board.  Adding a dowel to go across the bottom for ribbons she uses in her doll crafting plus pegs to hang scissors, french curves, and other pattern making devices she likes to have closes at hand.
     There would be any number of ways to construct this frame but I'm really partial to the tried and true mortise and tenon.  Yes, biscuits would work quicker, Kreg pocket hole joinery is another option, and now Festool has come out with their Domino machine but I'll stick to traditional work.  I'll go through my process and explain why I'm calling it a hybrid.
     First off, in our local woodworking group I'm known as one of the hand tool guys.  My philosophy though is to let machines I have perform the grunt work, similar to what an apprentice would do in a woodshop.  After running the material through the planer to make sure each piece is the same thickness I'll cut the pieces to rough length.  Next would be jointing an edge with a #7 Stanley and ripping each piece to the required width.  Once that's accomplished I use a hollow chisel mortiser to cut the mortises.

Cutting the Haunched Mortise

     As you can see there are stops set up so once that's done on one piece the other is guaranteed to be the same.  I used to cut mortises completely by hand but when I had a commission that needed about 24 of them I figured it was time to open my wallet!
     The next logical step is to cut the shoulders, this is done on the table saw using a sled and of course, another stop block.

Cutting Shoulders

     In this case I clamped a one inch spacer to the rip fence and used that as a stop block to assure the same distance for each.  Since this will be a haunched tenon I cut both of the faces and one edge.  I use an old Delta tenoning jig and make a shallow trial cut first.  Usually I'd have some scrape material to do trial cuts but this is all the Poplar I had!

Tenoning Jig

     After making a shallow cut, the sides are cut off with a dovetail saw and bench hook:

Trial Cut to Fit Tenon

     This is then checked to see how it fits the mortise:

Checking Tenon Fit
     Any adjustment can be made to the tenoning jig, I prefer to leave them very slightly oversized and then use a rabbet block plane from Lie-Nielsen to get that perfect fit.

Trimming Tenon Cheeks 

     Through the years I've tried many ways to trim tenons and this is by far, the best method for me.  Chisels and shoulder planes have been tried in the past but for me, the plane allows me to get an even trim on the tenon.  It's wide enough to cover most tenons in one pass and there's enough surface area to make that cut even.  Shoulder planes are narrow and just didn't fit my style.  Notice a good old fashioned bench hook -- went a little crazy with that and used it as an excuse to practice my dovetails.
     Once the tenons fit that way I'd like them to all that's left is to cut the haunch:

Final Step

     Since the haunch location could be slightly different on each mortise (eye-balled to the line) it's important to lay them out by transferring the  measurements from the exact mortise it will be joined to.  As a rule, I'll stamp a letter on each tenon face and mortise with metal working stamps.  Naturally this is put in an area where it won't be seen once the parts are together and it really helps when it's time to glue up.  The final step is to use a chisel to put a slight chamfer on the ends of the tenon.
     So there you have it, what I call my Hybrid Method.  In our woodworking group we've had discussions on using power tools versus hand work.  Many of the members take the position that if the cabinet and furniture makers of old had access to table saws, jointer, planers, etc. they would have surely used them and I'd tend to agree with that position.  Personally, when I first started taking on part time jobs while I was a teacher all I had were the hand tools. If a jobs came up that required a lot of mortises I bought the mortiser,  when I had a lot of book matched panels to make I upgraded the bandsaw, and so on.
     There's a balance all of us woodworkers need to find where we're comfortable doing the work we do.  I strongly favor hand cut dovetails, planed surfaces, hand beaded details, and oil finishes rubbed in by hand.  Once the grunt work is done there's nothing quite as satisfying to me than to finish the project with the quiet work of hand tools.  You know, ask a group of five woodworkers how to do a certain aspect of woodworking and you're liable to get five different  answers!

No comments:

Post a Comment