One common mistake is failing to line up the blade with the cutting guide. The guide should be positioned so the blade will cut through the center of the board. If the guide is off by even a fraction of an inch, it can throw off your entire cut. Another possible reason for misaligned cuts is that the saw's blade is not perfectly perpendicular to the surface of the board. This can be corrected by adjusting the saw's position or using a different cutting blade.