How to Replace Jointer Knives

Like all knives, jointer knives work best when sharp. If your jointer starts to produce uneven shavings or starts to burnish your work, it's time for you to remove the three knives and replace them or have them professionally sharpened. If you are replacing them, replace the entire set at once; if you are having them sharpened, instruct the person doing the sharpening to remove the same amount of metal from each knife. This will ensure that the cutterhead remains balanced.
Step 1Center the retaining wedge in the cutterhead slot with the grooved edge up. With the beveled edge facing the outfeed table, place the knife between the wedge and the front of the slot. The knife edge should be even with the outfeed table.

Step 2Cover the knife edge with a rag and partially tighten each lock screw; then start from the center screws and tighten them completely. Repeat step one and step two with the two remaining knives.

Step 3Check that the knife edges are even with the top of the outfeed table. If a knife is too high, loosen the lock screws slightly and insert a wooden wedge to hold the cutterhead still; then tap the knife down with a wooden block. Tighten the lock screws and check the level again.

Step 4If a knife is too low, loosen the lock screws slightly and insert a wooden wedge to hold the cutterhead still; then use a screwdriver to pry up the knife. Tighten the lock screws and check the level again.