Those look really nice. I don't know anything about the Porter Cable saw but first thing that comes to mind is there is not enough tension on the blade. When you insert the blade and apply the tension does the blade produce a really high ping when plucked? If it produces a low noise or "thud" type, you have to get the blade much tighter. If it is very tight, then the next thing would be bearings if it is an older saw....so the arms are simply moving back and forth. Another is forcing the work into the blade, especially when turning, instead of letting the saw cut at it's own speed. But great work!