The 3" setting was more like 4.5" actual. Instead of a blade height measurement tool which I never should have bought-I used a socket that was exactly 3" tall to and measured the blade tips front, back and side to side with the dial on 3". The 3" tall socket served as a "Go-No Go" Gauge. Then once the deck was perfectly level, I lowered the front two height adjuster bolts 1 full turn and raised the back two height adjuster bolts 1 full turn. And now the "Disclaimer"- I found this deck leveling technique from a Youtube video-this idea is not mine.