Whether you are a beginner, hobbyist, or a pro at planning stock, these are the things you must never forget. I recommend you people NOT to cut stock that may have defects, splits, knots, and foreign objects like stone, metal, etc. In addition, planing end grain is a dangerous idea. It can shatter the cutting board into multiple pieces and wreck the whole equipment. Not to forget the injury this can cause to the people operating the machinery. It is noteworthy to mention here that you should stay away from running a plywood through the thickness planer. When plywood is planed cross grain, layers of it comes off. This, in turn, forms fibers that block the dust port of the planer.