Jointers are one of the most useful woodworking tools — and one of the scariest.

Take it from me: I almost lost a thumb to a jointer, and I still give them 1 and ⅞ thumbs up.

But the truth is, it’s easy to use a jointer safely and effectively.

With the 9 tips below, you’ll have no problem getting your lumber square…

And keeping your fingers round.

Don’t have a jointer? Check out these 6 ways to joint a board with tools you already have.

The outfeed table is the flat surface to the left of your cutterhead.

It’s the reference your board will be flattened to — so the height needs to be precise.

You want the outfeed table to sit just about flush with the highest point of the cutterhead, but a hair lower.

If the outfeed table is too high, you won’t be able to push your board through. Too low, and you’ll end up with a curved face.

Here’s how to set it to the right height.

Unplug your jointer and grab your most trusted combination or t-square.

Place the blade of your square on the outfeed table so it overhangs the cutterhead. Hold it lightly in place.

Now use your hand to rotate the cutterhead clockwise.

The cutterhead blades should catch the square just enough to move it slightly towards the infeed table — while lifting the square as little as possible.

Adjust the height of the outfeed table until you get there. Then set it and forget it (but check periodically).

As with all power tools, taking small bites is best.

The maximum depth you should cut depends on your machine’s voltage.

If your jointer is:

• 120v: Don’t cut more than 1/16 inch (1.5 mm) in a single pass
• 220/240v: Don’t cut more than ⅛ inch (3 mm) in a single pass

The height of your infeed table (to the right of the cutterhead) will determine the cutting depth.

Most jointers have a cutting depth gauge, but you can also place a square on your outfeed table and check how high above the infeed table it overhangs.

Seriously though, don’t overdo it.

Taking multiple smaller passes will keep you safer, give you better results, and avoid overworking your jointer.

Jointer cutterheads usually come in two styles: segmented (a.k.a. spiral or helical) or straight knife.

While straight knife cutterheads are cheaper and quicker to install, they’ll end up costing you more in the long run.

That’s because segmented cutterheads stay sharp longer and produce cleaner cuts with less tearout — especially in highly figured hardwood.

They’re also a LOT quieter. That may not sound like a big deal…and that’s the point.

You love woodworking — but I’m willing to bet you love your fingers more.

Jointers can be serious digit-destroyers (take it from me), but a few precautions will keep your phalanges safe:

• Use push blocks: A push block in each hand is a layer of protection between your hands and the blade — something you’ll be grateful for in the event of a kickback. Need some push blocks? Get them here.
  
  
• Touch the fence while edge jointing: When applying downward pressure with your right hand, run your fingers along the top of the fence. This gives you something to catch if your board or hand slips. Use a push block in your left hand to push the board flush against the fence.
  
  
• Don’t push from the back of the board: It can be tempting, but pushing from the back of the board with your thumb is a recipe for disaster. If it’s that difficult to push the board through, you either need to reduce the cutting depth or wax the tables.
  
  
• Keep the cutterhead guard on: The only time you should remove the guard is if you’re cutting a board wider than your jointer capacity or using the rabbeting ledge.

If your board is cupped or bowed, run it through the jointer with the concave side down (rainbow, not smiley face).

This keeps your board stable as you run it over the jointer.

Grain direction can also affect your final results. Look at the edge of your board to determine how the grain is running.

To avoid chipping or tearout, feed your board so the edge grain is running downhill into the infeed table (running down from left to right).

This is tricky with highly figured wood (i.e. impossible), but it’s good to keep in mind.

One of the biggest mistakes I see newer woodworkers make on the jointer is keeping pressure on the infeed table for too long.

Remember, the outfeed table is the reference for flattening the board.

If you put all the pressure on the infeed side, it’ll lift the board and you’ll end up with a curved face.

As you pass your board over the cutterhead, transfer your push paddles to the outfeed side as soon as there’s enough board to push.

This is what makes your board flat.

Do the same while edge jointing, but while pushing your board flush against the fence (just make sure your fence is square).

Set your board on a flat surface (like the outfeed table) and find the low corners of the board.

These will be the two opposite corners that always touch your table when the board rocks.

When your board passes onto the outfeed table, transfer pressure diagonally from one of these corners to the other

This will cut them down to the same level as the high points of your board. You can then follow up with another pass or two to fully flatten the face.

Most boards should be flat with 2 to 3 passes on the jointer.

But to check, there’s a few things you can do:

• Mark the board with pencil: Mark all over the face you’re jointing with a pencil. When all the pencil marks are gone, you know the board’s flat.
  
  
• Check for sunlight: Set your board on the outfeed table or another perfectly flat surface. If there’s no visible light around the bottom edge, you should be good to go. (Bonus tip: Turn off the lights. All boards are flat in the dark).
  
  
• Feel the suction: If your board’s perfectly flat, you’ll feel a bit of suction when you lift it off your outfeed table — assuming the whole board fits within that surface.
  
  
• Check with a square: For edge joints, run your blade along the edge with the square’s fence on the flattened face. No spaces? You’re ready to move on to the planer and table saw.

Periodically rub down the outfeed and infeed tables with paste wax or 3-in-1 oil.

This will keep your boards running smoothly over the cutterhead so you don’t have to apply too much pressure when pushing them through.

If you’re consistently jointing boards thinner than your jointer capacity, move the fence position so you’re not always cutting with the same part of the blades.

This creates consistent wear across the cutterhead blades and makes them last longer. I probably do this about once a month.

Jointers need to be treated with respect — but with these tips, you’ll have no problem staying safe while getting great results.

Want a deeper understanding of the milling process? Read this.

What other jointer tips do you have? Let us know in the comments below!

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And as always, STAY SAFE IN THE SHOP!