Is there a structural difference between square-edged tenons and those with edges rounded to fit a routed mortise?
Andy Rae: Of course there are structural variations. But for woodworking purposes, the differences are negligible. Both joints are strong enough for most furniture applications. Instead of worrying about the strength, I fashion the tenon based on the type of mortise I make. For a routed mortise with round ends, it’s usually easier for me to round the tenon than to square up the ends of the mortise. If you find it easier to square the mortise to fit a square-edged tenon, go for it!