How to Use a Jointer for Creating a Reference Face
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A jointer’s first job is to create one flat, straight reference face on rough lumber. That face becomes the surface you register against a table saw, planer, or fence. If it is twisted, hollow, or cupped, every later cut inherits the error.
A jointer does not make a board uniformly thin. Its infeed table supports the uncut portion while the cutterhead removes material from the section passing over the knives. The outfeed table supports the newly cut surface at a fixed height. Understanding that relationship is more important than forcing the board through the machine.
Contents
Choose the Right Jointer
Jointer width determines the widest board you can flatten in one pass. A 6-inch jointer handles most furniture parts and common construction lumber. An 8-inch machine is more useful for wide tabletops, cabinet sides, and larger hardwood, but it costs more and takes more shop space.
| Jointer size | Best use | Main limitation |
|---|---|---|
| 6-inch | Legs, rails, stiles, shelves, and most narrow boards | Cannot flatten boards wider than about 6 inches |
| 8-inch | Wider furniture parts and small tabletop components | Higher price, larger footprint, and greater dust-collection demand |
| 12-inch or wider | Large slabs and production work | Expensive and excessive for many home shops |
A cheaper 6-inch jointer is fine if your stock is usually narrower than 6 inches or you are willing to glue up wide panels from jointed strips. If you regularly buy 8-inch boards, buying a 6-inch machine and trying to flatten them in sections is not a practical substitute. Look for a rigid fence, flat tables, a reliable depth adjustment, and a cutterhead that is easy to maintain. A helical or spiral cutterhead usually runs quieter and leaves smaller defects when a knife nicks the wood, but a straight-knife cutterhead is less expensive and can produce excellent results when its knives are sharp and aligned.
For current options, compare 6-inch wood jointers if you work mostly with ordinary boards. For wider stock, look at 8-inch wood jointers.
Prepare the Machine and Board
Before switching on the jointer, disconnect power and check that the tables are coplanar and the fence is square to the tables. A fence that is only slightly out of square can produce a reference face that is not 90 degrees to the edge. Verify it with a reliable square rather than trusting the fence scale.
Set the cut depth between 1/32 and 1/16 inch for typical hardwood. A 1/32-inch cut removes enough material for controlled flattening while reducing strain, tear-out, and snipe. You can use up to about 1/8 inch on straight, manageable stock, but deep cuts are rarely faster overall. They increase the chance of kickback and make it harder to control the board.
Inspect the board for nails, screws, staples, stones, and loose knots. Remove damaged sections if necessary. Mark the board’s faces with chalk or pencil. A simple set of marks on the face you intend to joint prevents accidentally flipping the board halfway through the process.
Place the board on the jointer and examine its shape. For a cupped board, begin with the concave side down. The two outer edges then contact the infeed table, giving the workpiece a more stable starting position. For a bowed board, start with the hollow side down when possible. If the board rocks badly, take very light cuts or use a different flattening method; a jointer cannot safely correct every severely distorted board.
Joint the Reference Face
Stand to the side of the cutterhead, not directly behind the board. Start the machine and let it reach full speed. Keep both hands above the board and away from the cutterhead opening. Push the board forward with steady pressure, moving it in the same direction as the grain whenever practical.
At the beginning of the cut, apply downward pressure over the infeed table. Once roughly 6 to 8 inches of board has passed the cutterhead, move your leading hand to the outfeed table. Continue pressing down on the already-flattened section while your trailing hand pushes the uncut portion forward. This handoff prevents you from pressing a hollow board into the infeed table and reproducing its curve.
Do not press down directly over the cutterhead. That can force the board below the intended cutting plane and create a dip. Do not stop halfway through a pass, either. Pausing can leave a visible step or uneven section. If the board is longer than your tables, use infeed and outfeed support at the same height as the machine tables.
Take another pass only after checking the surface. Use a straightedge or winding sticks to identify high areas. Continue until the reference face is flat along its length and width. You do not need to remove every saw mark if the face is already flat; removing extra wood wastes thickness.
Check the Result
Use a straightedge across the width and along the length. A combination square can reveal whether the face is reasonably flat, but winding sticks are better for detecting twist. Place one stick near each end and compare their edges from several feet away. If the edges do not appear parallel, the board still has twist.
Mark the finished face with a clear reference symbol, such as a triangle or series of lines. That mark tells you which face should stay against the planer bed or table saw surface. Next, joint one edge with the finished face against the fence. Keep the reference face firmly on the table so the edge becomes square to it.
After two faces and one edge are prepared, use a thickness planer to bring the opposite face parallel to the reference face. A planer alone cannot reliably flatten a twisted board because it follows the board’s existing underside. The jointer establishes the starting plane; the planer duplicates that plane at a controlled thickness.
Common Failures and Fixes
A tapered board: You may be lifting the trailing end or applying pressure in the wrong place. Shift pressure to the outfeed side as soon as enough board is supported there.
A dip in the middle: You are probably pressing down over the cutterhead or allowing the board to rock. Use lighter pressure and keep support on the outfeed table after the handoff.
Tear-out: Reduce the cut to about 1/32 inch, slow your feed slightly, and reverse the board if the grain direction changes. Sharp knives and a helical cutterhead can help, but neither eliminates difficult grain.
Edge not square: Recheck the fence with a square and keep the reference face flat against the table. Do not correct a fence problem by tilting the board during the cut.
Use push blocks when the stock is short, narrow, or difficult to grip. Keep hands out of the cutterhead area, wear eye and hearing protection, and connect a properly sized woodworking dust collector. A reference face is useful only if the machine and operator produced it safely and repeatably.
