Understanding the Role of a Jointer in Woodworking
Jointer questions have gotten complicated with all the beginner confusion about what the machine actually does versus what a planer does and how they work together. As someone who milled lumber by hand for years before getting a jointer, and then rebuilt my entire milling workflow around it, I learned everything there is to know about what a jointer does and how to use it correctly. Today, I will share it all with you.
What a Jointer Actually Does
The jointer creates a single flat face and a single straight edge on a board. That sounds simple, but it is the foundation that makes every subsequent milling operation accurate. Rough lumber from the yard or the sawmill has faces that are cupped, twisted, or bowed — the sawing process produces variation, and wood moves further as it dries. None of those faces are flat enough to register reliably against a fence or a table. The jointer fixes that by removing material from the high points across a single pass until the face is genuinely flat.
That is what makes the jointer endearing to us furniture makers — it is not a glamorous machine and it does not make final cuts, but without it the rest of the milling sequence does not work. A planer makes a second face parallel to the first, but only if the first face is already flat. If you skip the jointer and run rough lumber through a planer, the planer follows the existing shape of the board and produces a board that is uniformly thick but still cupped or bowed.
How a Jointer Works
The jointer has two tables — the infeed and the outfeed — with a rotating cutter head between them. The outfeed table is set level with the top of the cutter head. The infeed table is set lower by the depth of cut, typically 1/32 to 1/16 inch per pass. You place the board on the infeed table, feed it across the cutter head, and the outfeed table supports the portion of the board that has already been cut flat. The flat reference surface grows with each pass until the entire face has been machined.
The Milling Sequence
Probably should have led with this because it is the context that makes the jointer make sense: the correct milling sequence is joint one face flat, plane the opposite face parallel, rip one edge straight on the table saw using the flat face against the fence, and then rip or joint the second edge parallel. Every step depends on the one before it. The jointer is step one because everything else references from that first flat face. Skip it and the downstream accuracy suffers throughout.
Jointer Types and Sizes
Jointers are sized by their maximum cutting width — the capacity of the bed. A 6-inch jointer handles most furniture and cabinet work; it accommodates face jointing boards up to 6 inches wide and edge jointing any typical lumber width. An 8-inch jointer handles wider stock for tabletops and panel work. The 6-inch Powermatic 60B and the Jet JJ-6CSDX are the most recommended machines in the serious hobbyist range — both have spiral cutter heads that cut more quietly, produce less tearout on difficult grain, and last significantly longer between resharpening than straight knife heads. I am apparently someone who ran a straight-knife jointer for years before upgrading to a spiral head, and the spiral head works for me while the straight knife setup never handled figured maple cleanly the way I needed.
Common Problems and Solutions
Snipe — a deeper cut at the beginning or end of a board — happens when outfeed table height is not exactly level with the cutter head. Check and adjust the outfeed table height first when you see snipe. Tearout on the surface of the board means you are feeding against the grain rather than with it; flip the board and feed in the opposite direction. Burning means you are feeding too slowly or the depth of cut is too shallow for the cutter speed — either feed faster or increase the depth of cut slightly. A board that still has a twist after multiple passes usually has a twist severe enough that you need to remove the high corners with a hand plane before the jointer can reference correctly.
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