That branch is about 3" or 4" but remember this is a pear so it’s very soft wood nothing like a hickory or harder wood like you work with a lot. When it’s harder wood like a 4" or 6" mulberry then I change to rind aka bark graft quickly as shown here Che, mulberry, osage orange, fig grafting . Every tree and every situation is different. That year was hard on those Duchess d’ angoulme grafts some of that scion wood was as big as your thumb. I don’t like the way it grows or breaks. Duchess is very soft wood. It stays dormant longer then grows out very weird. The guy who I got the scions from has breaks every year because the pears get so big and the wood is soft. Those cleft grafted trees are these trees A windfall of windfalls!