Panels, miters
Splined edge
A loose strip in matching grooves adds glue surface and keeps an edge aligned.
Use when
- A plain glue joint needs help staying aligned.
Don’t use when
- Do not run a solid spline across a wide panel's seasonal movement without room.
- 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.
Sizes
| Mark | Size | Rule |
|---|---|---|
| Spline thickness | 1/4 in | One third of the stock, snapped |
| Groove depth, each edge | 1/4 in | Same as the spline thickness, so the spline is buried |
| Spline width | 3/4 in | 3/4 to 1 in across the joint. Grain of the spline runs across the joint |
| Groove fit | 1/4 in + 0.002 | A hair wider than the spline so glue has a place |
Cut sequence
1Plow both grooves
A plow plane or a scratch stock. Center the groove in the thickness.
Setup: Groove 1/4 in wide, 1/4 in deep.
2Mill the spline
Grain runs across the joint, not along it. The spline should slip in with hand pressure.
Setup: Width 3/4 in across both grooves.
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 spline adds glue surface and keeps the faces in plane. It does not stop a wide panel from moving.