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Bracket sets
斗栱
dǒugǒng

Dougong Bracket Set (一斗三升): How a Simple Chinese Bracket Set Goes Together

Dougong · 斗栱 · 一斗三升

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Bracket sets (斗栱) carry the eaves of Chinese halls. Large ones have dozens of parts.

The simplest, one block and three small blocks, shows the principle in five pieces.

Chinese
一斗三升 · yī dǒu sān shēng
Unit
斗口 (dou-kou): the width of the cap block’s slot
Joins
Plate, cap block, arm, small blocks, beam
Found in
Qing official buildings
Signature parts
Cap block slot · bracket arm · pins between layers
Drag to rotate. Slide to take the joint apart, or press Assemble to watch it go together.

How it works

A module, not a size

Qing bracket sets are measured in 斗口, the width of the slot in the cap block; every part is a multiple of it. In Ma Bingjian’s drawings the cap block is 3 斗口 square and 2 high (base 0.8, waist 0.4, ears 0.8), the central bracket arm is 6.2 long, 2 high and 1.24 thick, and the small blocks are 1.4 wide and 1 high. The plate under the set is 2 high and 3 wide. The model uses these proportions.

Layer by layer

The cap block sits on the plate; the arm drops into the slot between its ears; small blocks stand on the arm; the beam lies in their slots. Between the plate and the cap block, and between the layers of the set, pins (栽销) stop the parts from shifting.

Simplified

The curved ends of the arm (卷杀), the slot for the board between sets and any cross members are left out.

How it's made

  1. One set
    Step 1

    One set

    One cap block, three small blocks.

  2. Pinned
    Step 2

    Pinned

    The cap block is pinned to the plate.

  3. Cap block
    Step 3

    Cap block

    Base, waist and ears: 0.8, 0.4, 0.8 斗口.

  4. Arm
    Step 4

    Arm

    The arm sits in the slot.

  5. Small blocks
    Step 5

    Small blocks

    Three small blocks, each pinned.

  6. Beam
    Step 6

    Beam

    The beam rests in the blocks.

Variations

Projecting sets

Larger sets add arms that project outward in steps (出踩).

Column-head and corner sets

Sets over columns and at corners are built differently.

Can you CNC this?

Yes, with small changes

The cap block, arm and small blocks are blocky parts with straight slots, well suited to 3-axis milling; curved arm ends would be a 2D profile. Pin holes are drilled.

Free STL downloads (one file per part)

Before cutting or printing, read the CNC and 3D-printing notes on tool radius, scaling the STL files and their licence.

Questions

What is a 斗口?

The slot width of the cap block; the module for every part.

What holds the layers?

Pins between each layer.

Is this a full bracket set?

It is the simplest kind, without projecting arms.

Further reading
  1. 马炳坚《中国古建筑木作营造技术》第二版（Ma Bingjian, Timber Construction Techniques of Traditional Chinese Buildings, 2nd ed.），第 223–260 页
  2. 马炳坚《中国古建筑木作营造技术》第二版（Ma Bingjian, Timber Construction Techniques of Traditional Chinese Buildings, 2nd ed.），第 240 页，图 6-2
  3. 马炳坚《中国古建筑木作营造技术》第二版（Ma Bingjian, Timber Construction Techniques of Traditional Chinese Buildings, 2nd ed.），第 126 页，图 3-11
  4. 马炳坚《中国古建筑木作营造技术》第二版（Ma Bingjian, Timber Construction Techniques of Traditional Chinese Buildings, 2nd ed.），第 165 页