How to use a surface planer
Whether you use a surface planer, a jointer or hand planer largely depends on what you need to accomplish, for though they’re all planers, they require different expertise.
Here’s how to use a surface planer.
Before using a surface planer, use a jointer to create an absolutely flat surface and a true vertical edge. The surface planer then takes over making the other surface of the board absolutely flat so the top and bottom of the board are identical. Because the process was started with a jointer there won’t be any twisting or cupping.
Without the jointer’s first step, the surface planer cannot create or straighten a twisted or cupped board (although there is a way, which we’ll discuss later) but it does effectively reduce the lumber to a board of the required thickness.
How to use a surface planer
Portable surface planers have a completely flat bottom table and infeed and outfeed tables or rollers that are set at the same height. The spinning cutting drum is in the head of the planer. It removes material from the top.
Surface planers will size a board to the precise thickness required. What they will not do is true a board (see tip for a way around this). That’s because the planer has a roller feed that pinches the board top and bottom as it feeds it past the rotating blades. So if a board is cupped or twisted, the action of the feed will squeeze the board in the vicinity of the blades and duplicate the twist or cup as it passes through the knives.
That’s why a jointer is used first to flatten one surface and one edge. Then as the board passes through the surface planer, it matches the surface the jointer has already cut on the other side.
The surface planer has an adjustable housing for the blade drum and feed rollers that can be cranked up and down to achieve the required thickness for the board. It has a polished bottom plate that the board slides over as it is pulled and pushed by the infeed and outfeed rollers.
Usually 1/32 to 1/16 inch of material is removed in a pass, though the hardness of the wood may allow more or less. The hand wheel to adjust the cutter head is usually geared so that a full revolution moves the planer head 1/8 inch. There will be a gauge showing the position of the cutting blades but it may or may not be correctly calibrated.
Some models also have a depth stop that can be set to the maximum thickness of material to be removed. The surface planer may also have a selector labeled ‘finishing cut’ and ‘dimensional cut.’ It’s really a speed control for the rollers. At low speed, you’ll get more blade cuts per inch and a finer finish. The speed control can only be adjusted with the planer running.
When using a planer, tremendous quantities of wood dust are created so a powerful shop vac or permanent dust-removal equipment should be attached to the planer head. Ear and eye protection are also required.
Under no circumstance should your hands ever be under the planer head. Beware of jams that can occur if a cut is too aggressive or as the knives start to dull. And, to avoid injury from kickbacks, stand to the side as you feed a board into the rollers.
For initial cuts, you can set the surface planer head height by testing the board. Insert the board and adjust the head height until the board clears, then lower the height adjust 1/16 inch or less and make the first pass.
It’s a good tip to draw pencil or chalk lines on the surface to be planed so you can see the progress of the wood removal. You’ll be able to see the high and low spots, and know when you have matched the surface of the other face of the board.
Another issue can result from the feed, where a couple thousandths of an inch of additional material is removed as the board moves into and out of the planer. This is called snipe. If possible, plane a board that is longer than you need and saw off the snipe on each end.
Or you can use a sacrificial board ahead of the workpiece at the beginning of the pass. Then as that board moves off the outfeed place it at the back of the workpiece where it can take the outgoing snipe, as well.
If the workpiece is fed in the wrong direction, tear-out can result. To fit it, flip the board around and plane with the grain.
If you have a board with twist, you can fix it with a surface planer even if you don’t have a jointer. To do this, make a plane sled using flat plywood a little wider than the workpiece. Hot glue wedges between the board and the sled until it’s doesn’t rock. Now run the workpiece through the planer. When the workpiece is completely flat, remove the sled, turn the board over and plane the other side. This technique can also be used on a cupped board, planing the concave surface first.
How to use a planer safely
Planers have fast-spinning drums with exceedingly sharp blades. There is no room for complacency when using them. Always keep hands well clear of the spinning knives.
Planers throw dust and fast-moving wood particles so wear eye protection and ear protection is also highly recommended.
Never operate a planer while wearing loose clothing and never walk away from a surface planer until the drum has stopped spinning.
Lumber generally holds more moisture at the center than at the surface. As you remove the surface, you’ll expose moister wood. If possible, plane close to the required dimension and then allow the board to stabilize for a day or so. Then you can plane it to the final dimensions.
–By Steve Sturgess, SteveSturgess.com