Apron-to-leg, door rail-to-stile
Mortise and tenon (stub)
A tenon on the rail sits in a mortise that does not come through the leg or stile.
Use when
- An apron meets a leg, or a door rail meets a stile, and the far face should stay clean.
- You can cut the mortise before any taper on the leg.
Don’t use when
- Do not make the tenon thicker than about a third of the rail.
- Do not rely on a very short stub, with no shoulder, on a chair that racks.
- 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 |
|---|---|---|
| Tenon thickness | 1/4 in | Nearest common bit to 1/3 of the rail (1/4 in raw) |
| Tenon length | 1-1/8 in | 2/3 of the leg width, clamped, snapped down to the nearest 1/8 in |
| Tenon width | 2-1/2 in | Rail width minus a shoulder on each edge |
| Edge shoulder | 1/4 in | Default 1/4 in top and bottom |
| Cheek | 1/4 in | (rail thickness − tenon) / 2. Keep both cheeks even |
| Mortise width | 1/4 in bit, plus 0.002 in | Tenon thickness + 0.002 in. Cut with the tenon bit; the extra is a file pass, not a wider bit |
| Mortise depth | 1-3/16 in | Tenon length + 1/16 in so glue has somewhere to go |
Cut sequence
1Mortise the leg first
Mark the mortise on the leg before any taper. Chop or drill the waste, then pare the walls. Leave the extra depth at the bottom for glue.
Setup: Width = 1/4 in. Length along the leg = 2-1/2 in. Depth = 1-3/16 in.
Stop when: Walls are square and the floor is deeper than the tenon.
2Gauge the tenon from the same setting
The gauge that marked the mortise marks the cheeks. Saw cheeks first, shoulders second, so the cheek saw still has wood to ride.
Setup: Thickness 1/4 in, length 1-1/8 in, width 2-1/2 in, edge shoulders 1/4 in. Cheeks 1/4 in each side.
Stop when: Shoulders meet in a clean corner and the tenon is centered.
3Fit the cheeks
Plane a cheek until the tenon starts by hand and the shoulders close on both faces. Do not crush it in with a clamp.
Stop when: Shoulders are tight and the rail does not rock.
4Dry-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
structural
Movement
Cheeks are long grain to long grain. The rail still moves across its width; the shoulders and a centered tenon let it do that without racking the leg.
Common mistakes
- Cutting tenons before mortises, then tapering the leg and losing the layout.
- A mortise drilled crooked, so the rail twists.
- Shoulders that meet on one face and gap on the other.
- No room at the bottom of the mortise, so glue hydraulic-locks the tenon proud.
- Cheeks of different thickness, so the rail sits off the center of the leg.