Xiujian Yanwei (袖肩燕尾榫): Sleeve-Shouldered Dovetail
Sleeve-shouldered dovetail · 大头榫
Tie beams between columns must not pull apart, even when the frame sways.
The beam ends drop into the columns on dovetails. Many early Ming and Qing buildings add a short collar at the root: the sleeve shoulder.
- Chinese
- 袖肩燕尾榫 · xiùjiān yànwěi sǔn
- Joins
- Tie beam to column
- Found in
- Large Ming and early Qing buildings
- Proportions
- Tenon 3/10 of column diameter long: sleeve 2/5, dovetail 3/5
- Related
- Dovetail
How it works
Dovetail down into the column
The column head has a dovetail socket open at the top. The beam end is cut to a dovetail as tall as the beam and drops in from above, so it can’t pull out sideways.
The sleeve
Beam dovetails come with or without a sleeve shoulder. With one, the tenon is 3/10 of the column diameter long: the sleeve takes 2/5 of that and the dovetail 3/5. The dovetail flares by about 1/10–1.5/10 and tapers slightly from top to bottom; the sleeve does not.
How it's made
Step 1Dovetail
Cut a dovetail on the beam end.
Step 2Sleeve
Leave a short sleeve shoulder at the root.
Step 3Socket
Cut a matching socket, open at the top, in the column.
Step 4Drop in
Drop the beam in from above.
Step 5Can’t pull out
The dovetail holds the beam.
Step 6Sleeve helps
The sleeve adds bearing at the root.
Variations
Without sleeve
A plain dovetail 3/10 of the column diameter, as tall as the beam.
Can you CNC this?
Possible, with design or setup changes
The dovetail flares in plan, so the beam end can be cut lying flat and the socket cut from the top of the column. The column may need to stand upright, and the socket’s inside corners will be rounded.
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)
- Column 柱 · xiujian-yanwei-column.stl
- Beam with dovetail 带燕尾的梁 · xiujian-yanwei-beam.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
Clasping-Head Tenon
gūtóu sǔnThe beam drops into a slot across the column head and runs on past it; the head beyond “clasps” the column.
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.
Column-Head Tenon
mántou sǔnA short square tenon on the column head fits a socket under the beam, so the beam can’t slide off.
Questions
What is a sleeve-shouldered dovetail?
A beam-end dovetail with a short collar at the root, dropped into the column head.
How long is the tenon?
3/10 of the column diameter: sleeve 2/5, dovetail 3/5.
Where is it used?
Large Ming and early Qing buildings.