Joint for Morris Chair Arm

[Jan Bianchi]

I need a joint where the flat arm of a Morris-style rocking chair connects to the front leg. I don't want to use the traditional through mortise and tenon that protrudes through the face of the arm because I won't be able to set my coffee cup down on it. But other chairs like this are notorious for the joint failing over time and the arm coming loose every time you move the chair by the arms.

The arm is 7/8' bent lamination, but 4' wide so it would be hard to run a screw through it and then through the tenon. I thought maybe cutting two rounds rather than one round or square mortise might provide more glue surface. I've only got about 1/2-5/8" to work with for the tenon on the leg so I'm guessing an angled tenon wouldn't work. Or should I use a regular mortise and tenon, but use epoxy instead of wood glue? Any ideas for a joint that will last? I'm a brand new Gramma, so this has to be good.

[Bob Lang]

Your best choice is to peg the tenon crossways if you can. Inside of the arm is likely to best place to drill a 1/4" hole through the side of the arm and into the tenon. Drive in a dowel to secure the joint. Epoxy won't save a poor-fitting joint, especially if there are issues of wood movement or stress on the arm, it will crack eventually and will be a pain to remove to make a repair.

If you can select the leg stock so that it shrinks and swells with the width of the arm, your prospects are better. There isn't much room to place the peg so you have to work carefully.

Bob Lang

[Kevin Groenke]

Hey Jan,

How about a wedged-flush-through-tenon? This would provide the joint with all of the mechanical strength and glue surface area of the traditional "crowned" through mortise PLUS the added mechanical strength of a wedged joint: AND you get your desired flat arm. The use of contrasting wood for the wedges could be a nice design element which could be incorporated elsewhere in the chair.

http://americanwoodworker.com/cfs-filesystemfile.ashx/__key/CommunityServer.Blogs.Components.WeblogFiles/techniques/12155_5F00_jointworks.jpg

http://lh6.ggpht.com/_rHdeE-SI5cc/SYeAle_hsLI/AAAAAAAAAq0/xhNVYNcyNnc/s512/bed%20backcornrdet.jpg

[Rod Sheridan]

On my chairs I avoided the through tenon also, as we like to put a mug of tea on a coaster there.

I made the joint with a non through mortise and tenon, and the top rail of the gable is glued into a groove in the underside of the arm.

The rear chair leg is also fastened with a non through tenon.

You won't have any failures with those joints, as the twisting forces on the arm are carried by the corbels.

Regards, Rod.

[Jan Bianchi]

Ron

I don't know what a gable is in this context. Rather than confess I tried looking it up in my Encylclopedia of Furniture Making, but no enlightenment there. There is what I call a side slat with corbel in the chair that is attached half way back to under the chair arm in a groove. Is that what you are referring to? If so, a regular mortise and tenon joint with glue will hold the arm and the stress is handled by the side slat and corbel?

[Jan Bianchi]

Kevin, that's a beautiful joint. I hope I can find a simpler way, but I will keep it in mind for my next chair

[Jan Bianchi]

I thought about a dowel but worry about the length of the tenon. Maybe Ron's idea about the corbel handling the stress means I don't have to worry about this?

[Bob Marino]

Hey Jan,

How about a wedged-flush-through-tenon? This would provide the joint with all of the mechanical strength and glue surface area of the traditional "crowned" through mortise PLUS the added mechanical strength of a wedged joint: AND you get your desired flat arm. The use of contrasting wood for the wedges could be a nice design element which could be incorporated elsewhere in the chair.

http://americanwoodworker.com/cfs-filesystemfile.ashx/__key/CommunityServer.Blogs.Components.WeblogFiles/techniques/12155_5F00_jointworks.jpg

http://lh6.ggpht.com/_rHdeE-SI5cc/SYeAle_hsLI/AAAAAAAAAq0/xhNVYNcyNnc/s512/bed%20backcornrdet.jpg

As mentioned - beautiful joinery.

Bob

[Jan Bianchi]

The more I look at this, the more I like it as a solution. I already have some walnut inlay elsewhere, so the wedges would fit right in. But I'd end up with the end grain on the face of the arm. Do you see that as a problem?

[Jim Koepke]

I need a joint where the flat arm of a Morris-style rocking chair connects to the front leg. I don't want to use the traditional through mortise and tenon that protrudes through the face of the arm because I won't be able to set my coffee cup down on it.

Confucius says, "Man who sets coffee cup on rocking chair arm soon look to have wet pants."

jim

[Kevin Groenke]

I don't see how the end grain will be a structural or functional problem. Whether it is works aestheticly may be debatable. The arm of the chair is not of a thickness that seasonal movement would result in significant movement of the cross-grain elements. I have never noticed that the joint on the pictured headboard has ever been anything but flush. Again there is the aesthetic, but the joint would be an honest revelation of the structure of the piece, so it would be consistent with Arts & Crafts design principles. I don't think Stickley or Hubbard would have a problem with it. Done well it could be quite beautiful. With patience and sharp tools it's not particularly difficult to execute: curves and/or angles would complicate matters.

FWIW, we have a bow arm morris chair with 4.5" wide arms, the 1" x 1" pyramidal tops of the tenons really don't interfere much with a coffee cup. Those M&T's are pegged through the centers from the inside of the arms: 4+ years of daily use and everything is still solid. I think I used tite-bond3. Look Ma - no corbels.

-kg

http://lh5.ggpht.com/_rHdeE-SI5cc/SWA3geOzEII/AAAAAAAAAT8/tRGcl3p97xw/s576/kevin%20groenke.jpg

[Rod Sheridan]

Ron

I don't know what a gable is in this context. Rather than confess I tried looking it up in my Encylclopedia of Furniture Making, but no enlightenment there. There is what I call a side slat with corbel in the chair that is attached half way back to under the chair arm in a groove. Is that what you are referring to? If so, a regular mortise and tenon joint with glue will hold the arm and the stress is handled by the side slat and corbel?

Sorry for the confusion, I used the word gable to indicate the side of the chair.

My chairs are sloped arm designs with a horizontal member underneath the arm to receive the tenons of the spindles.

The horizontal member is let into a groove in the under side of the arm.

Strictly speaking a gable is a side of a structure such as a cabinet side.

Regards, Rod.