Saline River Workshop lists a Solid Oak High Table and Chair Set built with mortise and tenon construction.
A tenon is a projection cut on the end of a rail. A mortise is the matching hole in a leg or post. Researchers have measured how the shape and size of that joint change its strength.
What a 2005 Test Found
Ali Naci Tankut and Nurgül Tankut published the test in the Turkish Journal of Agriculture and Forestry, volume 29, issue 6. They glued T-shaped joints of beech, conditioned at 12 percent moisture content. They stored the joints for 14 days at 22 degrees Celsius and 65 percent relative humidity and then loaded them to failure.
- Wider tenons: Strength rose with tenon width. For one rail width, a 1.5 centimeter increase in tenon width raised bending strength by about 25 percent.
- Wider rails: Joints with 5 centimeter tenons on 7.5 centimeter rails were about 14 percent stronger than the same tenons on 5.5 centimeter rails.
- Square ends: Rectangular tenons in rectangular mortises were about 15 percent stronger than round tenons in round mortises.
- Mismatched ends: The authors advise against rectangular tenons in round mortises for chairs. They found the strength came mainly from excess glue and not from mechanical fit.
- Clearance: The small gap between tenon width and mortise length had a negligible effect.
- Against dowels: Comparing with earlier dowel data from another researcher, the authors found mortise and tenon joints about 40 percent stronger than joints with two dowels at the same rail widths.
The test used beech. It did not test oak, walnut or pecan.
Moisture and Joints
The Wood Handbook from the USDA Forest Products Laboratory describes how wood changes size as humidity changes. It says the objective of drying is a moisture content close to the one the finished product will have in service. Read the numbers in Solid Wood Movement in Tabletops.
Questions to Ask a Furniture Maker
- Joint list: Ask which joints in the piece are mortise and tenon and which use other methods.
- Tenon size: Ask how wide the tenon is compared with the rail. The test above ties width to strength.
- Fit: Ask whether the mortise and tenon have matching ends.
- Moisture: Ask what moisture content the lumber held when the joints were cut.
Mortise and Tenon at Saline River Workshop
One listing names the construction in its title: Solid Oak High Table and Chair Set, Mortise and Tenon Construction. Other listings, including the Lumberjack Ladder Back Chair, do not state their joinery in the title. Ask the workshop through the contact page, which lists a workshop in Wilmar, Arkansas. The Encyclopedia of Arkansas places Wilmar in Drew County, which the Saline River separates from Bradley County.
For the timber behind the region’s furniture, read Saline River Bottomland Hardwoods and Warren, Arkansas Hardwood and Custom Furniture.
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