Often the length of a span in a timber frame is longer than the size of your lumber. That is when you will need to use a scarf joint to join two timbers together. There are many types of scarf joints, and this under squinted stop splayed scarf joint with screws is one of them.
Say that three times fast! This under squinted stop splayed scarf joint with table and wedge is a classic timber framing joint. The complexity adds great strength , and it’s a great looking joint for any frame.
All scarf joints serve the same purpose- to join two timbers together to span a distance greater than the dimensions of your lumber. There are many variations on the basic scarf joint, and this under squinted stop splayed scarf joint is one of them.
Anytime you need to span a distance longer than the lumber you have on hand, scarf joints are a good solution. This stop bladed scarf joint with cogs and wedges is a half-lap joint with stops, also called tongues or blades. The cogs in this joint are the t-shape projections in the cogs.
Like all other scarf joints, you can use this joint to create a longer beam out of two shorter timbers. The cogs in this joint are the t-shape projections in the tenon. Since they help lock the joint in place, they also increase the bending strength against horizontal loads.
This stop bladed scarf joint with cogs takes a bit more work to cut than a simple bladed scarf joint. But the cogs (the projections into the tenon that form a t-shape) added to the stub tenons help lock the joint in place.
If you need to span a distance greater than your lumber dimensions, scarf joints are the way to go. Another variation on the scarf joint, this stop bladed scarf joint is a half-lap joint with the addition of the stops, also called tongues or blades.