Xiujian Yanwei Sun: The Sleeve-Shouldered Dovetail Joining Beams to Columns
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.
Related joints
Clasping-Head Tenon (箍头榫)
The beam drops into a slot across the column head and runs on past it; the head beyond “clasps” the column.
Dovetail Joint (燕尾榫)
A 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 (馒头榫)
A 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.