Steve...SteveMaryland wrote: ↑Tue Dec 12, 2023 10:04 pm Ed, not sure which sort of scarf joint would work. See attached illustration. Which one did you have in mind?
Looks like if I took two scraps and joined them with a scarf, I would wind up with a piece not much longer than the original scraps. Lots of glued area however...
What I was thinking of is the Plain Scarf joint, which is simply a long bevel on one end of each of the two pieces to be joined.
Although the strength of a scarf is hard to determine precisely, the internet says that with a slope of 1 in 12, and using modern adhesives, you can expect something like 80-85% of the strength of a solid board of the same dimensions.
Here is a description:
Scarf, Plain
A plain scarf joint connects two pieces of wood end-to-end using overlapping, diagonal cuts without additional interlocking features. This slanted connection increases the surface area for bonding, offering a more robust attachment than a simple butt joint. However, because of its lack of mechanical interlocking, the plain scarf joint's strength heavily relies on the adhesive used or, occasionally, supplementary fasteners. Common in woodworking and carpentry when extending beams or planks, it is essential to ensure proper alignment during assembly. The plain scarf joint exemplifies the idea of simplicity in design, prioritizing efficient use of materials and a smooth, elongated bond.
Plain Scarf Wood Joints have full widths and scarf angles between of 10-30 Degrees. Typically used in wood members with widths between 1.5”-3.5” (3.8-8.9 cm) and depths between of .75”-3.5” (1.9-8.9 cm).