A dado is a square-bottomed channel cut across the grain of a board. Shelves, cabinet sides and bookcases often use dadoes because they provide support and help align parts. Learning to cut dadoes opens up stronger, cleaner furniture designs.
This guide explains what dadoes are and how to cut them with a table saw, a router or hand tools.
Dadoes, Grooves and Rabbets
- Dado: A channel across the grain
- Groove: A channel along the grain
- Rabbet: A step cut along an edge
The same techniques often apply to all three.
Why Use Dadoes
- Support shelves along their full width
- Help align parts during glue-up
- Add glue surface
- Create clean, strong joints
Planning and Layout
Width
The dado width should match the thickness of the mating part. Plywood is often slightly thinner than its nominal size, so measure actual thickness.
Depth
Dadoes are often cut to a fraction of the board’s thickness. Deeper dadoes weaken the board; shallow ones provide less support. Follow project plans or common guidance.
Marking
Mark dado locations on both mating boards. Mark both edges of the dado with a knife or pencil and square.
Method 1: Table Saw
Dado Stack
A dado stack is a set of blades and chippers that cut wide channels in one pass. Not all saws accept dado stacks; check your manual. See table saws for garage shops.
Steps
- Install the dado stack following the manual, using the correct throat plate
- Set width with chippers and shims
- Set depth
- Use a miter gauge or sled to guide the board
- Make test cuts in scrap and check fit
- Cut the dado
Multiple Passes With a Standard Blade
You can cut dadoes with multiple passes using a standard blade, nibbling away material.
Safety
Do not use the fence as a stop with a miter gauge for crosscuts unless using a proper stop block setup. Follow manual guidance and keep guards in place where possible.
Method 2: Router
Straight Bit
A straight bit or spiral bit cuts dadoes.
Guide
Clamp a straightedge to guide the router, or use a dado jig.
Steps
- Choose a bit matching dado width, or plan multiple passes
- Clamp the guide
- Set depth, taking shallow passes
- Rout with the correct feed direction
- Test fit
Tips
Take multiple shallow passes rather than one deep pass. Secure the workpiece. Wear eye and hearing protection.
Method 3: Hand Tools
Tools
- Saw
- Chisel
- Router plane, optional
Steps
- Mark the dado edges with a knife
- Saw along each edge to depth
- Remove waste with a chisel
- Level the bottom with a router plane or chisel
Hand-cut dadoes are slower but quiet and satisfying.
Getting a Good Fit
A good dado fit is snug but not forced. If the joint is too tight, sand or plane the mating part slightly. If too loose, glue alone may not fill gaps; shims or a new cut may be needed.
Glue-Up
- Dry fit first
- Apply glue to the dado walls
- Clamp parts square
- Remove squeeze-out
Alternatives
Pocket holes offer a simpler option for some shelves. See pocket-hole joinery.
Common Mistakes
- Not measuring actual plywood thickness
- Cutting dadoes too deep
- Misaligned dadoes on mating sides
- Taking deep router passes
- Skipping test cuts
Questions to Ask Before You Cut
- Is the dado width matched to the actual thickness of the part?
- Are the dadoes on mating sides laid out from the same reference edge?
- Is the depth appropriate for the board thickness?
- Which method fits my tools and comfort level?
Laying Out Matching Dadoes
For bookcases and cabinets, dadoes on left and right sides must line up. A reliable approach is to clamp the two sides together edge to edge and mark across both at once, or to use the same stop block setting for both. Label each side and mark which face is the inside.
Stopped Dadoes
A stopped dado ends before reaching the front edge, hiding the joint from view. Stopped dadoes are usually cut with a router and require squaring the end with a chisel or rounding the mating shelf.
Practice Exercise
Cut several dadoes in scrap plywood with your chosen method, then test-fit offcuts. Practice builds confidence before cutting project parts.
Router Feed Direction
Feed direction matters with routers. When routing with a handheld router, feeding in the wrong direction can cause the router to pull or climb unexpectedly. Follow your router manual for correct feed direction relative to bit rotation. Take light passes and keep both hands on the router.
Final Pre-Glue-Up Check
- All dadoes cut and cleaned
- Dry fit successful with snug joints
- Clamps and cauls ready
- Glue and squeeze-out cleanup supplies ready
- Square or tape measure ready to check diagonals
Common Questions About Fit
If a dado is slightly too tight, lightly sanding or planing the mating part is often easier than recutting. If a dado is slightly loose, the joint may still work for hidden shelves with glue and screws, but gaps will show at the front edge. Test-fitting before cutting all parts avoids most fit problems.
A Note on Plywood Edges
When a dado runs through to the front edge of plywood, the layered edge is visible. Many woodworkers cover front edges with solid wood edging or iron-on veneer tape after assembly, which also hides the dado ends.
Frequently Asked Questions
What is the difference between a dado and a groove?
A dado runs across the grain; a groove runs along it.
How deep should a dado be?
Commonly a fraction of board thickness; follow project guidance.
Can I cut a dado without a dado stack?
Yes, with multiple passes, a router or hand tools.
Do dadoes need glue?
Glue usually adds strength.
Why is my plywood loose in the dado?
Plywood is often thinner than nominal size.
The Bottom Line
Dadoes create strong, aligned joints for shelves and cabinets. Cut them with a dado stack, a router and guide or hand tools. Measure actual thickness, make test cuts and aim for a snug fit.
Editorial note: Joint Bench is independent and reader-supported. This guide is based on research into manufacturer documentation, published specifications and widely accepted best practices; we have not been paid to mention any product. If we add affiliate links in the future, they will be clearly disclosed per our Affiliate Disclosure.