I bet your set stop is set wrong, it is the bolt in the picture under the depth knob, get a 1/2" wrench and loosen the not that is on it then lower it and all the way down, then get an 1/8" board set it in the planer lower the head until it just touchs the board then raise the set stop while your depth knob is set to 1/8" you can also do ir with an 1/4", 1/2" 3/4" just set your depth dial accordingly.