Firstly, ensure that the screws of the blade are tightened and that the blade of the pvc cutter is not loose. In order to cut a perfect kerf, please keep kerf distance pipe mouth at least 1.5inch. You have to make sure the pipe is perpendicular to the blade and the pointed center of the blade hits the center of the pipe when you begin cutting. Then please rotate the pipe a little bit and do the cutting job.