Planer Jointing Sled

Get a piece of 3/4" MDF large enough for the sled. Mine was 48" x 12", so I used a piece of MDF that was 48" long and about 15" wide. Regular MDF is fine, but I used a piece of MDF core veneered oak plywood for a little better face durability.

I used some remaining scrap and my table saw to cut an edge piece 1" wide and then glued and nailed it to the straight edge of the sled. I then used a trim router with an 1/8" rounover to smooth all the peg holes.

Cut several pegs from a 3/4" dowel. I'd recommend a hardwood dowel for durability. You don't want the pegs to hit the planer knives, so keep them a bit under 1 1/2". I cut mine on the bandsaw.

You'll then want to cut some wedges. Again, I'd recommend a hardwood. I has some Aspen lying-around that I used. Square-off the narrow ends of the wedges so you can hammer against that edge with something to remove them when done plaing. Again, make sure the wedges are only a bit less than 3/4" when on their sides to keep them from hitting the planer knives.

Take your board and butt it up against the straight edge. If the board is especially twisted you may want to shim it relatively straight underneath. Insert dowels in the nearest available holes that can have wedges inserted. Hammer the wedges between the dowels and the board in several locations. You'll want to make sure they are all snug, but don't get crazy with it.

You can now run the sled through the planer. You may want to setup infeed and outfeed rollers to keep things level on both sides and to assist holding the jig since it is quite heavy. Once you get one face flattened you can knock-out the wedges and flip the board and run it through the planer by itself to get 2 square sides. You can then joint an edge on your jointer if you have one or use a track saw or table saw with a jointing jig.