Peg a joint and you add a mechanical lock. It’s why so much was pegged in situations where the antique glues would fail. Pretty much all joints can be pegged and there are numerous methods and materials used in pegged joinery. Nails and screws can be thought of as modern variation of a wooden peg. Knowing a variety of methods to peg common joints is a great tool to have in your arsenal. But it’s especially useful for educators.
Teachers tend to measure initial joinery success by if the work goes together at all. But a student brings details into the picture. No more so than when teaching/learning dovetails. This joint has become a rite of passage for woodworkers. I’m clueless as to why. And it seems they’re always disappointed when their first one isn’t perfect even after the speech about: “a tee-ball player isn’t gonna hit a home run on their first swing, a kindergartner isn’t gonna color in the lines… but, they will eventually hit the ball and the picture will get color”.
Because of the unjust importance placed on the dovetail milestone you as a teacher need to make sure the students’ work is successful the first time. This might mean building up to that first attempt, giving them too much practice cutting in the waste, or setting up methods to fix errors early so it doesn’t appear that the teacher is pinch-hitting after the fact.
I do this by introducing pegs early. If all students are successful on the first go round then it’s just added information about pegs why, how and benefits. But if a student’s work needs a little help… then I have a resource to draw upon that doesn’t make it obvious a student buggered up.
An easy way to discuss pegs is in the “why’s.” Where to start the first tail?
If your pins on the outside have a little meat to them you can drop a peg from the top and bottom into the first and last tail. This creates a mechanical lock without affecting the aesthetics of the dovetail. It’s also helpful in future repairs (or if a student splits the pin board).
Thin or thick pins? Spacing them out allows you to interlock pegs thru both pins and tails, thus creating a joint for abuse (and students who can’t figure out what side of the line to cut on.)
Further the informative ruse by citing historical examples of both these peg additions. They’re everywhere.