Open Straight-Tenon Box Corner (明榫角接合)
Box joint · Finger joint · 直榫开口接合
A drawer has four corners where thin boards meet at right angles. There are several ways to join them, from showy to completely hidden.
The plainest is the open straight-tenon corner, which shows on both faces.
- Chinese
- 明榫 · míngsǔn
- Also called
- 直榫开口接合
- Joins
- Two boards at a right angle
- Found in
- Plain, rough pieces; drawers
- Compare
- Half-blind dovetail · Fully hidden dovetail
How it works
Straight tenons, open
Each board end is cut into straight tenons with open gaps between them, and the two ends interlock at the corner.
Showing on both faces
The end grain of the tenons shows on both outside faces. Wang Shixiang calls it the simplest of the corner joints for drawer sides, and says Ming and Qing furniture used it only on rough, everyday pieces.
The better ways
Next comes the half-blind dovetail, which shows on one face only, and then the fully hidden dovetail, which shows nothing.
How it's made
Step 1A corner
Two boards meet at a corner.
Step 2Tenons
Cut straight tenons on one end.
Step 3Matching
Cut the other end to match.
Step 4Slide together
Slide them together.
Step 5Shows both ways
The tenons show on both faces.
Step 6Rough pieces
Used only on rough pieces.
Variations
Half-blind
Shows on one face only.
Fully hidden
Nothing shows.
Can you CNC this?
Yes, with small changes
Box-joint fingers suit a 3-axis machine with the boards clamped upright, or a router table jig. The inside corners of the slots come out rounded, so small dogbones or rounded finger edges may be needed.
General note: a round cutter cannot leave a sharp inside corner, so every recess keeps the tool radius. Round the mating edges or add dogbone reliefs. Sloping faces, undercuts and curves may need special bits, extra setups or more axes.
Free STL downloads (one file per part)
- Front board 面板 · mingsun-jiao-front.stl
- Side board 侧板 · mingsun-jiao-side.stl
Proportions are illustrative, not measured dimensions. The files are unitless: scale them to suit and check fits and allowances before cutting. Each file is a closed (watertight) solid with its mortises and slots already cut, exported in its assembled position, ready to import into CAM or modelling software. Licence: CC BY 4.0 (credit: Chinese Joinery).
Related joints
Half-Blind Dovetail
bànyǐn yànwěi sǔnDovetails on the side board fit sockets that stop short of the front face, so the joint shows on one face only.
Hidden Mitred Dovetail
mèn sǔnDovetails hidden inside a mitred corner: once closed, only a single seam line shows.
Dovetail Joint
yànwěi sǔnA tenon wider at the tip than at the root, so it can’t pull out: found in boxes, drawers, tables and temple beams.
Questions
What is a mingsun corner?
A corner of straight, open tenons that show on both faces.
Was it used on fine furniture?
Wang Shixiang says only rough everyday pieces used it.
Is it like a box joint?
Yes, it is the same idea as a modern box or finger joint.