Tuesday, January 29, 2008

The Wedged Through Tenon

The wedged through tenon is another type of through tenon used in Arts and Crafts Furniture. The process for making the mortise is much the same as the previous post, except that once you get the mortise on the bench to clean it up you must flair the outside ends of the mortise out about one eighth of an inch. This will allow the tenon to be spread by driving a couple of wedges into it, this gives the joint holding power against being pulled back through the mortise. Once the mortise is ready and the tenon is cut you need to drill a hole about a quarter of an inch from the shoulders of the tenon, this will keep the split in the tenon from spreading once the wedges are driven in. The next step is to make a cut from the end of the tenon down to the hole.

You should now cut wedges that are the width of the tenon, they should be just a little longer than the relief cut on the tenon and just a little wider than the slope you cut in the mortise. I prefer to use a contrasting wood as the wedges are an important part of the exposed joinery, but make sure that you are using a hard wood. Since I use quartersawn white oak I usually make my wedges out of wenge or ebony.

The tenon can then be set in the mortise with a coat of glue on the faces and shoulders of the tenon. You must be ready to move along because you have a limited amount of open time with the glue. Start one wedge in the relief cut a quarter of an inch then start the other wedge, using a small block to protect the wedges gently tap them in a little at a time, alternating one then the other. You should end up with an equal amount showing on each wedge when you are finished. Don't attempt to pound them in flush, once them stop moving stop hammering, otherwise you will break the wedge off inside the mortise. Once the glue has dried carefully trim off the excess wedge material and sand flush. You now have a very strong joint that is beautiful as well, a joint that is an integral part of your arts and crafts piece, rather than being hidden its there for the world to see, to celebrate the craftsman that took the time to create it.
Gustav Stickley's motto was "Als Ik kan" it translates from the German to "As I Can", or, more to the point, "To the best of my Ability". , a worthy goal for us all.



6 comments:

Luis said...

Hi Brad, great work with SketchUp!

Luis said...

Hi Brad,

One quick note you didn't mention in the post: one must remember that the wedges must go perpendicular to the grain of the piece that has the mortise or there is a risk of splitting the piece when you hammer those wedges into the mortise.

Brad Ferguson said...

Luis,
Thanks for the comments, while I agree that there is a danger of splitting when you are not perpendicular to the grain, when you are using quartersawn white oak it is difficult to do this, this is why I recommended drilling the relief holes in the tenon. I have also used the wedge diagonally across the grain for a more decorative touch without trouble. You will notice in the last photo that I did go perpendicular to the grain, however in a long tenon this won't work with the wood. So, yes, its best to go perpendicular to the grain, but I'd say, be aware that you may risk cracking the piece if you must go parallel to the grain if you aren't careful.
Thanks again,
Brad

Margaret said...

What an interesting site! I love Arts and Crafts furniture and just discovered Stickley. I wish I knew more about woodworking--it must be so amazing to be able to create these pieces.

Brad Ferguson said...

Thank you Margaret, its nice to see that my blog is reaching more than just woodworkers, please keep coming back.

Brad Ferguson said...
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