How to cut a dado on a table saw

1. Mark the start and stop points for the dado
2. Mark the height on your piece to match the desired depth of cut
3. Cross hatch the areas for removal
4. Adjust the fence and blade to match your removal areas
5. Make your boundary cuts
6. Remove the remaining material by making multiple passes
7. Test fit the mating piece as you near closer to the second boundary

At this point, we will assume that your workpiece is flat against the table saw top and has been squared. If making two dados for something like a cross lap joint, you’ll want to ensure that both pieces have been joined and planed correctly. 

Mark the Start and Stop Points for the Dado

Begin by clearly marking where the dado will start and stop on each workpiece. Use a pencil, marking knife, or layout tool to ensure straight, accurate lines. A marking knife will provide for greater precision, so this is the preferred tool. These marks will serve as your left and right boundaries. 

Mark the Height to Match the Desired Depth of Cut

Next, determine how deep the dado must be. Again, make a mark with a marking knife or pencil. This mark needs to be visible enough so that you can adjust the table saw’s blade height to it. 

Cross-Hatch the Areas for Removal

Lightly draw a series of cross-hatch lines within the boundaries you’ve marked for material that needs to be removed. 

It’s very easy to get upside down or turned around and remove the wrong section of material. Make marks on multiple sides of the cut piece so it’s explicitly clear for what is to be removed and what isn’t. 

Adjust the Fence and Blade to Match Your Removal Areas

With your markings in place, set your table saw’s fence so that the edge of the blade aligns just inside of your left or right mark. At this point, it does not matter which you cut first. 

Now adjust the blade height to match the depth you established.Spin the blade a few times to check and ensure none of the tips pass your mark. If you’re unsure, lower it below the line, proceed to the next step, then come back and raise if needed.

Make Your Boundary Cuts

Begin by making two initial cuts along the left and right lines you marked earlier. These boundary cuts define the exact width of the dado and serve as boundaries for all subsequent passes. Starting with these controlled cuts helps ensure you don’t accidentally cut too far.

Consider making one or both of these boundary cuts just a hair within your marks so you can come back later and ensure a snug fit. 

Remove the Remaining Material by Making Multiple Passes

Now that the boundaries are set, remove the excess material within them. Move the fence slightly between passes to incrementally cut away the cross-hatched area. Slow and steady provides a cleaner, safer, and more accurate cut. 

Test Fit the Mating Piece as You Approach the Final Boundary

As you near completion, pause to test-fit the mating piece. This check ensures the dado is the correct width and depth. If adjustments are needed, make small, precise changes to the fence or blade height. By doing so, you’ll achieve a perfect, tight-fitting joint in the final result.

Troubleshooting

Issue: Joint is too loose

Solution: Restart with a new piece of material. Too much material had been removed from the current workpiece. Double check the marked measurements and ensure the initial boundary cuts are within the marked lines. As material is removed, incrementally cut towards the marked line for a snug fit. 

Issue: There’s tear out or blow out on the work piece

Solution: Depending on where the blowout is, there’s several possible solutions. Consider adding a zero-clearance insert to support the wood fibers near the blade and reduce splintering. Make a light scoring pass along the marked line with a marking knife, box cutter, or other sharp blade designed for precise cuts. You may also add painter’s tape over the marked area to further support the wood fibers. 

Issue: There’s a v-shaped gap on the top/bottom of the dado

Solution: Use a flat-top toothed blade. The v-shape that remains is the result of an Alternate Top Bevel blade, or ATB blade, which is standard on most table saws. The teeth on the blade have an alternating slant that are best suited for general purpose cuts. A flat top blade, as the name implies, has a flat top on the tooth, thus removing material at a flat 90 degrees relative to the table. 

FAQ

What’s the difference between a groove and dado?

A groove is a channel cut parallel to the grain of the wood, whereas a dado is cut perpendicular to the grain. Although both are similar types of recesses, the orientation of the cut relative to the wood’s grain distinguishes a dado from a groove.

What’s the difference between a dado and rabbet?

A rabbet is a recess cut along the edge of a board, typically on the end or side, creating an L-shaped notch. In contrast, a dado is a slot cut across the face of a board, not limited to the edge. While both are used in joinery, rabbets frame an edge, and dados provide slots within the panel’s surface.