How to Joint the Face of a Board Without Creating a Taper
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Jointing the face of a board means creating one flat reference face before using a planer, table saw, or other machine. The common mistake is removing more wood from one end than the other, leaving a board that looks flat but is tapered. That usually comes from uneven hand pressure, lifting the board onto the outfeed table too early, or taking too large a cut.
Contents
Choose the Right Machine
A jointer is the correct stationary machine for flattening one face. Its infeed table is lower than the cutterhead, while the outfeed table supports the board after the knives remove material. A planer can make the opposite face parallel, but it cannot reliably flatten a board that rocks or has a hollow underside unless you use a sled.
| Method | Best use | Main limitation |
|---|---|---|
| Jointer | Flattening one face and straightening one edge | Board width is limited by the cutterhead capacity |
| Thickness planer | Making the second face parallel to a reference face | Follows a cupped or twisted bottom unless supported |
| Planer sled | Flattening wide or badly twisted boards | Slower setup and less convenient for light work |
| Table saw with sled | Removing a controlled amount from a board edge or side | Not a substitute for face flattening on wide stock |
For routine furniture stock, a 6-inch jointer is adequate for many boards, while an 8-inch machine gives you more useful capacity. A woodworking jointer is worth considering if you regularly process rough lumber. If you only buy surfaced boards and occasionally need to correct a face, a thickness planer with a sled may be the cheaper and more versatile choice.
Prepare the Jointer Before Cutting
Check that the tables are clean and locked, the fence is square, and the knives or cutterhead are correctly installed. A dirty table can change how the board sits as you push it. Wax or a dry lubricant can help the board slide, but avoid a wet or oily product that can contaminate a finish.
Set the cut shallow. For ordinary rough lumber, start with 1/32 inch or less. On a badly twisted board, a 1/16-inch cut may be useful for the first pass, but it increases resistance and makes poor feeding technique more likely. Never use a deep cut to compensate for a short or unstable board.
Inspect the board for nails, screws, embedded grit, and loose knots. Mark the face you intend to joint with a pencil. If the board is cupped, place it so the two high edges contact the infeed table first; this reduces rocking. If it is badly twisted, identify the high corners and take extra care to keep the board stable during the first passes.
Feed the Board Without Creating a Taper
Start with the board fully on the infeed table and keep your hands well clear of the cutterhead. Apply downward pressure over the infeed table, not directly over the knives. Push at a steady rate, typically around 10 to 20 seconds for a 6-foot board, depending on the cut and the machine. Do not stop in the middle of a pass unless safety requires it.
The critical change happens when the leading end reaches the outfeed table. Move your forward hand onto the flattened section and apply pressure there. Keep your other hand on the infeed side only long enough to maintain control, then move it forward. Your pressure should follow the board, not remain concentrated at the front or rear.
Do not press down hard on the trailing end while the front is being cut. That pushes the unflattened portion into the table and can cause the jointer to remove more material from the leading end. The result is a tapered board. Likewise, pressing down on the leading end after it reaches the outfeed table can lift the rear of the board and leave a hollow or uneven face.
Use push blocks or push pads designed for jointers, particularly with short stock. For long boards, an infeed or outfeed support stand should be adjusted to the same height as the table. A support that is too high lifts the board; one that is too low lets the board sag. Either condition can create a taper.
Check Progress Instead of Chasing Perfection
After each pass, inspect the pencil marks. Pencil lines show where the cutter has contacted the face and are more useful than relying on appearance alone. Keep taking light passes until the high areas are gone and the face is consistently machined. You may not need to remove every rough patch if the face is already flat enough for your project.
Check the face with a reliable straightedge across the width and along the length. A winding stick is helpful for detecting twist. A board that is flat along its length but twisted corner to corner is not ready to serve as a planer reference.
Measure thickness at both ends and in the middle with calipers or a rule. A difference of more than about 1/32 inch on a board that should be parallel is a warning that your feeding pressure or support needs correction. Jointing one face does not make the opposite face parallel; use a planer afterward with the jointed face down.
When the Board Is Too Wide or Unstable
If the board is wider than the jointer, do not try to balance it precariously on the tables. Use a planer sled made from a flat panel, with shims or hot-melt glue to stop the board from rocking. Run the assembly through the planer until the upper face is flat, then remove the supports and plane the opposite side normally.
A sled is also the better option for severely twisted stock. The trade-off is time: setup may take 15 to 30 minutes, and you lose some thickness. For occasional work, a thickness planer and a simple sled can cost less than buying a wide jointer.
Common Failure Modes
A concave face usually means you kept downward pressure on the front or back of the board instead of transferring it smoothly to the outfeed table. A convex face often comes from lifting the board as it exits or from using an outfeed table that is set too low. Snipe-like dips at the ends can indicate incorrect table alignment or pressure changes during the pass.
Keep the cutterhead sharp, make light cuts, and let the machine do the work. A sharp set of jointer knife replacement blades reduces the force needed to feed the board and makes consistent pressure much easier. The goal is not to flatten the board in one pass; it is to establish one trustworthy reference face without forcing the stock into a shape of your own.
