Did you not see my Thread on Measure Once Cut Twice ? it's a mistake when I was dadoing the grove for the miter track I use a 6'' reversible pocket rule and I used the wrong end to mark the 4 1/2 '' from the edge so it turned out 2 1/2'' from the edge. The track is aluminium and the laminate is grey so I decided it looks fine. I think I will put some tape or paint on the other side of the ruler so I don't make that mistake again.
Don't fear your tools, pay attention and respect the tools and avoid injury.