I found that scribing a path for the blades to follow helped a bunch. This can be done either before or after the surfaces are covered. If covered, make a cut with an Xacto blade and then scribe a line in the balsa. Then, and this is the important step, hold the Slot Machine so that only a corner of the blade is touching the scribed line. Start the cut with just the corner of the blades and as it bites, rock the tool so that the blades are flat against your surface and lined up with your scribed line. This will keep the tool from dancing or bouncing out of your scribed cut. It took much longer to type this than to actually do it. After you use the tool a few times, this is all one motion that takes only seconds to make a perfect slot.