HomeownerWithTrees

So when you say make a clean cut - a cut closer to the main trunk of the tree, in a ring following around the branch collar?

As per title, I've cut a large branch (6inch diameter) off a Sycamore Maple at the branch collar. The tree is taller than a terraced house. I'm now aware I've done pretty much every no-no in the book cutting at spring, further than the collar and a large branch. I'd like to know what the risks of damage are to the tree and if there's anything I can do to help it heal, and prevent disease or death(?!) Thanks very much in advance.