Shawn, MDF is medium density fiberboard, usually a light brown in color. Hardboard or "Masonite"(brand name) is high density fiberboard, usually a dark brown in color. Pegboard is made from hardboard. Stack the pieces you want to join. Measure and mark a line where you want your cut. Measure and mark the center point of your cut line. Make your cut using a 1/8" straight or spiral cutting bit. Stop just before the center line, take your pieces apart and check the fit. If they are not flush then stack them again and sneek up on the center line until they do fit.
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