[OBeer-WAN-Kenobi]

Were you having problems with the accuracy or repeatability of the angle itself or was it not making a square cut like the blade was tilting or walking?

I would think that you could remedy the first by using a combination square instead of relying on the markings on the saw or even drill your own holes and set up pins at the angles you use most often. I've never found the markings to be very precise. If the problem is tilting of the cut or walking of the blade a wider blade will help but it all boils down to sharpness, pressure (feed) and pitch. Feed it too fast and pretty much any blade will "walk" and make a cut that isn't square. A dull blade has the same effect. Too coarse of a pitch on a thin walled material will give you similar problems and try to grab.

You should get yourself a few different blades to use for different materials and workpiece shapes. A very fine pitch should be used with the thin walled stuff to keep from having it grab or make a generally bad cut. If you can, always try to have a minumum of 2 or 3 teeth in cut at all times. The fine pitch blades will also work better on harder materials and will leave less of a burr on all materials at the expense of cutting speed.