flattening a rocking board with a thickness planer

I’d say place wedges under the board to eliminate the rocking, and hot glue those wedges to a plywood base. It would be a quick and dirty way to duplicate results from a more elaborate and re-useable planer sled like this one.

-- Brian in Arlington, TX - Laziness is the foundation of efficiency.

take the guard off your jointer, send it though and then hand plane the 1”. Or a router plane would work well.

-- http://www.etsy.com/shop/KandJWoodCrafts

It’s the old argument, you cannot flatten a board with a planer. But if you take very small cuts with the warp up into the cutters, often the rollers will not straighten out the board on a simple bow far enough to defeat the cutter action, and flattening does occur just like on a jointer.
I’d try taking almost razor thin cuts with the middle bow facing up until you reach a flat on that side, then flip it over and with the flat side now down, take off the offending up edges if you want to. It is a whole lot better than wedges, glue, and other bandaids.
Then, you have a at least one flat side you can resaw out the 1” thick plank you need.
Of course, if it is a compound warp, forget it.

-- Paul, Tennessee, http://www.tsunamiguitars.com

Brian, lumberJoe, Paul

Thanks for the replies. I went ahead and tried the hot glue and it worked! When I pressed on the left back the right front only lifted about a 1/16th of an inch. so I just filled that side / edge and along the end with a puddle of hot glue and flipped it over and pressed hard on the back left.

-- Jesse, Saint Louis, Missouri

A fancy sled as referenced by Brian is nice but if you need a quick solution just take a piece of 1/2 inch or thicker plywood slightly wider and longer than your work piece and use it as a temporary sled. Place your work piece on your bench, lay the plywood on top of it and add shims as required so it won’t rock. Then screw the plywood to the work piece in several places. Make sure you countersink the screws deep enough so they don’t protrude above the plywood.
Flip the board/plywood assembly and run it through your planer until it is flat. Remove it from the “sled” and plane the other side.

Obviously you need to pick screw locations that won’t be visible on your finished piece. Also the screw length must be short enough so they won’t get planed.

-- Joe

I use a sled jig when planing stock wider than my jointer. The sled is nothing more than a strip of 8” wide plywood, with a cleat attached to one end.
1. start by taking one fairly deep cut at the jointer.
2. place the workpiece (jointed face down) on the sled. Let the rough edge overhang the side of the sled. The cleat should catch the back edge of the workpiece, so the jig and workpiece go through the planer together. Make multiple passes at the planer until you have one flat face.
3. Then remove the workpiece from the jig and plane the other side to the desired thickness.

With a 6” jointer, this technique works well for up to 12” wide boards. No hot glue, screws, or shims required.

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush