Adjust Tables for Jointer Accuracy

Q:

When I run edges of boards over my jointer, the leading and trailing thirds join perfectly for glue-ups, but there’s a gap between the middle third of the boards. The blades are set correctly, and the outfeed table is level with the cutting arc of the blades.
—Tony Grasso, Muncie, Ind.

A:

 Sounds like your tables aren’t coplanar, Tony. To correct this problem, start by unplugging the jointer, removing the cutter guard, and pushing the fence clear of the table. Then, back off the depth stop to raise the infeed table to the same height as the outfeed table. Center a metal straightedge over the cutters, and lay it across both tables. If you see light beneath the straightedge at one end, you’ve got a sagging table. 

Following the manufacturer’s recommendations, adjust the gib screws until the tables are coplanar—lying in a common plane. Then, lower the infeed table, check that the outfeed table is still level with the cutting arc, reset your depth stop, and replace the cutter guard before making test passes using scraps.

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