Tip #34
Planer
Pg. 1-3, Pg. 4-6, Pg. 7-9, Pg. 10-12, Pg. 13-15 (PDF)
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Surfacing Rough Lumber

Buying rough-cut lumber and doing your own custom surfacing is essentially no different than general planing, but there are a few tricks you should know.

Be sure the wood is properly dried. Wet or green lumber clogs the machine as you plane it. Sap builds up on the knives, interfering with the cutting action. And as the wood dries, the planed stock becomes uneven and requires resurfacing.

Air-dried wood should stand for at least one year per inch of thickness of the rough-cut stock. The moisture content of air-dried wood should be about 12% to 19%. You needn't worry about how long kiln-dried wood stands, but it should have a moisture content of about 10%. If the wood is to be used for fine furniture or cabinets, some woodworkers prefer a moisture content of about 7% to 8%.

To determine the amount of moisture in wood, cut a sample block from a board. (Don't simply cut off an end-ends dry quicker and this will give you a false reading. Instead, cut 6" off the board and discard the end; then cut off a second 6" for your sample.) Weigh the sample on a postal scale; then bake it in an oven for one to two hours at 200°F to remove all the moisture. When the sample is completely dry, weigh it again. Use this equation to calculate the moisture content of wood:

Joint one edge before surfacing a board. It's almost impossible to determine the grain direction in a rough-cut board. By jointing one edge before you plane a board, you can determine which way the grain is running and feed the board into the planer so that the knives cut with the grain.

Measure to find the thickest part of the board. As wood dries, its dimensions become inconsistent--including its thickness. Measure the thickness of a rough-cut board at several places and set the depth of cut for the first pass according to the thickest spot. Take very shallow cuts at first. Just as it's difficult to tell the grain direction in a rough-cut board, it's also difficult to tell how the grain is figured. To avoid ruining the wood, take shallow cuts (1/64" to 1/32") until you can tell whether there are any burls, bird's eyes, or other unusual grain patterns.

Remember to surface both sides. Plane one side until you have removed all the saw marks; then turn the board over and plane it to the desired thickness.

Continue to Planing Boards to Identical Thicknesses
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