Framers, however experienced, often miss this trick to cut the perfect corners with the Morso. The Morso like any piece of equipment is only ever as good as the person using it. Their idiosyncrasies need to be understood and worked around to get the best out of them. It is never as simple as one good downward thrust and bobs-your-uncle, the perfect corner cut.
The Morso has two cutting blades, sharpened to a high degree. The inner cutting surface is flat but the outer surface is curved. To get the best cut, both blades need to make the cut. When positioning a length of molding, to save on molding, framers often make the first cut with only one blade. They slice off a section of the molding at the very end and then after setting the correct measurements make the next cut. Without the two blades working together, the curved outer part of the cutting blade with nothing to hold the wood in place will push to one side. This results in the first cut not being straight. Only one of the corner cuts needs to be irregularly cut to make the frames craftsmanship look shoddy.
So the moral of the story is to always make every cut you make with the two blades. Doing this only means another few centimeters of molding is used but will make all your corners perfect.