Tops, backs, flooring-style panels
Tongue and groove
One edge carries a tongue, the mate carries the groove.
Use when
- Boards need to align and still be able to move a little.
Don’t use when
- Do not glue every joint in a wide solid top.
- Keep
- Waste, hatched on the drawing
- Dimension
- Long parts are broken. The 1 in bar is true scale.
Stock
Thickness steppers move by 1/16 in, or 0.5 mm. You can type 3/4 or 1-1/8.
- On a wide solid top, glue only a few joints. The rest stay free so the panel can move.
Sizes
| Mark | Size | Rule |
|---|---|---|
| Tongue thickness | 1/4 in | One third of the thickness |
| Tongue length | 1/4 in | One third of the thickness, into the groove |
| Groove width | 1/4 in + 0.002 | Matches the tongue, plus 0.002 in |
| Groove depth | 1/4 in | A hair deeper than the tongue is long |
Cut sequence
1Gauge the tongue
Tongue is 1/4 in thick and 1/4 in long, centered.
Setup: Groove 1/4 in deep.
2Saw the tongue, then the groove
Saw the shoulders of the tongue first. The groove can be plowed to match.
Stop when: The tongue enters and the faces flush.
3Dry-fit, then glue
Close the joint dry. Check that shoulders and faces meet, then glue. If this is a frame or a box, check both diagonals before the glue grabs.
Stop when: Dry-fit is tight with hand pressure, square, and the diagonals match.
Glue
Long grain to long grain
Strength
furniture
Movement
The tongue keeps boards aligned. A solid field still moves across its width.