9.3: Dadoes and Grooves
- Page ID
- 67207
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9.3 Dadoes and Grooves
The tool tote uses recessed cuts to locate and support other components.
Two important terms are:
Dado — A recess cut across the surface of a board.
Groove — A recess cut generally in the same direction as the grain.
In the tote, recessed cuts are used to:
- support the bottom panel; and
- locate the risers.
Learning Outcomes
After completing this section, you should be able to:
- Distinguish between a dado and a groove.
- Explain the purpose of the bottom groove.
- Explain why the bottom panel is allowed to float.
- Describe the purpose of the riser dados.
- Explain the basic idea of self-centering a dado or groove.
The Bottom Groove
A groove is cut along the inside lower portion of the box sides and ends.
A typical bottom groove is approximately:
1/4 inch wide
The exact location and depth will be demonstrated by your instructor.
The groove captures the edges of the bottom panel and supports it inside the box.
Through and Stopped Grooves
Depending on the corner joinery and construction sequence, some grooves may be able to continue completely through a part.
Others may need to stop before reaching an exposed end.
A stopped groove ends before it reaches the edge of the workpiece.
The goal is to support the panel without leaving an unwanted groove visible on the exterior of the tote.
The Bottom Must Move
The bottom is made from solid wood.
Solid wood expands and contracts across the grain as moisture conditions change.
For that reason, the bottom is fitted into the grooves but is not glued around its perimeter.
The panel must be able to move slightly inside the box.
This is called a floating panel.
Fit, Do Not Force
The bottom should fit into the grooves without excessive force.
A fit that is too tight may prevent normal wood movement or make assembly difficult.
A fit that is too loose may allow the panel to rattle.
Aim for a controlled fit that allows the project to assemble normally.
Riser Dados
The short ends of the tote receive recessed areas for the risers.
These dados help:
- locate the risers;
- keep them aligned;
- increase the joint area; and
- resist movement.
The riser fit should be established carefully.
The dado can be cut first and the riser fitted to the opening rather than relying only on a theoretical dimension.
Self-Centering
A useful woodworking technique is to create a centered feature by making matching cuts from opposite orientations.
The basic idea is:
- Make a cut near the center.
- Rotate or flip the workpiece.
- Make the same cut from the opposite reference side.
- Adjust the setup gradually until the feature reaches the desired width.
Because the same reference surfaces are used from both directions, the final opening remains centered.
Your instructor may use this approach for the riser dados or other centered features.
Sneak Up on the Fit
Do not remove the final amount of material all at once.
Make a test cut.
Check the fit.
Adjust slightly.
Test again.
Small changes to a stop block or machine setting can produce noticeable changes in a joint.
Once a dado is too wide, the removed material cannot be put back.
Label the Parts
Before moving on, keep track of:
- inside and outside faces;
- left and right ends;
- reference edges;
- riser locations; and
- any matched grain relationships.
These marks may become less visible during sanding, so think ahead about when they will still be needed.
Check Yourself
- What is the basic difference between a dado and a groove?
- What does the bottom groove do?
- Why is the bottom panel not glued around its edges?
- What is a floating panel?
- What do the riser dados accomplish?
- How can cutting from opposite orientations help center a feature?
- Why should you sneak up on a final fit?