How Jointers Improve Your Woodworking

Jointers have gotten underappreciated in modern shop setups, with some woodworkers thinking they can skip this machine by buying S4S lumber. That’s a workable approach for simple projects, but as someone who has worked both with and without a jointer, I know exactly what you give up when you skip this machine and why adding one changes what you can build. Today, I will share it all with you.

But what does a jointer actually do? In essence, it creates a perfectly flat reference face on one side of a board and a perfectly square edge on one side, giving you the starting reference surfaces that all subsequent milling operations depend on. But it’s much more than just flattening wood — a jointer is the first step in a milling sequence that turns rough lumber into precisely dimensioned stock ready for accurate joinery.

The Jointer’s Role in the Milling Sequence

Rough lumber from a sawmill or hardwood dealer is exactly that — rough. One or both faces are typically not flat (often bowed, twisted, or cupped), and neither edge is square. You can’t plane this stock to accurate thickness on a planer until you have one flat reference face, because the planer’s rollers will follow the twist and bow, reproducing the same distortion just thinner.

The jointing sequence: flatten one face on the jointer (the reference face), then run that face down on the planer to bring the opposite face parallel to it. Now you have stock with two flat, parallel faces at consistent thickness. Then back to the jointer to square up one edge, and to the table saw to rip the opposite edge parallel. This four-step sequence — joint face, plane thickness, joint edge, rip width — produces accurately dimensioned stock that’s ready for layout and joinery.

Skipping the jointer means starting the planer sequence without a flat reference face, which produces warped-but-thinner stock. It also means edge jointing by hand or at the table saw (which doesn’t remove twist), and the accumulated inaccuracy shows up in glue joints that don’t close, frames that won’t lie flat, and assembled projects that have subtle warps baked in from the start.

How the Jointer Works

The jointer has two coplanar table sections — infeed and outfeed — separated by the cutter head. The infeed table is set slightly lower than the outfeed table by the desired cut depth, typically between 1/32″ and 1/16″ per pass. As you feed the board across the infeed table, the rotating cutter head removes a thin layer of wood. When the board reaches the outfeed table — which is coplanar with the cutting arc of the knives — the freshly flattened section of the board rides on the outfeed table while the remaining section is still on the infeed, awaiting cutting.

The fence guides edge jointing at exactly 90° to the table (or at other angles for chamfers and bevels). The fence is the reference for squareness; it needs to be set accurately and checked periodically.

Components and What They Mean in Practice

The infeed table’s depth of cut setting directly affects how aggressively you’re cutting. Light cuts (1/32″) produce cleaner surfaces with less chance of tear-out in difficult grain. Heavier cuts (1/16″) remove material faster but require more care on figured wood. Start conservative with unknown species.

Outfeed table height is the alignment that matters most for quality results. If the outfeed table is too low, you get snipe — the end of the board dips and gets cut deeper than the rest. If it’s too high, the board rocks on the exit. The outfeed table should be coplanar with the apex of the cutter circle. Verify this with a straightedge across the tables when the knives are in position.

The cutter head type — straight knives versus helical/spiral cutterhead — makes a noticeable difference in surface quality, noise level, and how the machine handles figured wood. Straight knife heads are standard and produce good results on straight-grained stock. Helical cutterheads with carbide inserts arranged in a spiral pattern dramatically reduce tear-out in curly, figured, and reversing grain — and they’re quieter. The upgrade cost is significant but worth it for shops that work with figured hardwoods regularly.

Choosing a Jointer

The critical dimension is bed width — how wide a board the machine can flatten. A 6″ jointer handles most standard furniture and cabinet work. An 8″ jointer handles wider stock and is the serious hobbyist and small professional shop standard. Anything wider gets into professional production shop territory and corresponding prices.

Bed length matters for flattening long boards. A short jointer bed makes it harder to maintain control over an 8-foot board. Look for tables at least 42-48″ total length for a 6″ machine; longer is better.

Safety Points

Keep the guard in place. The cutter head is exposed when feeding stock, and the guard should be riding on the outfeed side, deflecting back over the cutter as the board passes. Many woodworkers remove the guard and then forget why it was there — until they don’t.

Use push blocks for narrow stock and for the final portion of any board pass. The push block keeps your hands on the board and away from the cutter head as the end of the board clears the infeed table. For boards narrower than 4″, push blocks are not optional.