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Bracket sets
平身科斗栱
píngshēnkē dǒugǒng

Pingshenke (平身科斗栱): How a Qing Bracket Set Is Built Layer by Layer

Intercolumnar bracket set · 平身科 · 单翘单昂五踩

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The bracket sets between the columns of a Qing hall look like a tangle of blocks and arms.

They follow one simple rule: every crossing is a half-lap, and the side members sit on top.

Chinese
平身科斗栱 · píngshēnkē dǒugǒng
Joins
Cap block, arms, projecting arms, crossing blocks
Found in
Qing official buildings, between the columns
Signature parts
Cross slot · half-laps · doukou module
Compare
One block, three small blocks
Drag to rotate. Slide to take the joint apart, or press Assemble to watch it go together.

How it works

The module

Every size is given in doukou (斗口), the width of the slot in the cap block. Ma Bingjian works through a five-step set with one projecting arm and one cantilever (单翘单昂五踩). The cap block (坐斗) is 3 by 3 doukou and 2 high, its base, waist and ears in the ratio 0.8 / 0.4 / 0.8. A cross slot is cut in its top, 0.8 deep: 1 wide for the projecting members and 1.24 wide for the arm along the façade.

The first crossing

The centre arm (正心瓜栱, 6.2 long, 2 high, 1.24 thick) and the first projecting arm (头翘, 7.1 long, 2 high, 1 thick) cross in that slot. All crossings follow one rule: members parallel to the façade are cut on top, members running into the building are cut underneath, and the façade members go in first.

The next layer

Crossing blocks (十八斗, 1.8 long) stand on the ends of the projecting arm and carry the outer arms (单才瓜栱, 6.2 long, 1.4 high); a longer centre arm (正心万栱, 9.2) sits on the first. Above come the cantilever (昂), the beam-head (蚂蚱头), the end arms (厢栱, 7.2) and the long tie-pieces (枋). The arm lengths assume a spacing of 11 doukou between sets and are scaled if the spacing differs. Small pins hold each layer to the next.

On the columns and at the corners

A column-top set (柱头科) carries the beam directly: its cap block is 4 doukou wide and its projecting arm 2 doukou thick, and the top layers are replaced by the end of the beam itself. A corner set (角科) must turn the corner: members that project on one face become arms on the other, and extra diagonal arms and cantilevers run out along the corner. In the sloping-tail type (溜金), the tails of the inner members rise along a slope towards the purlin and are locked together by through-pins.

The model shows the lower layers only; arm-end curves and the pins between layers are left out.

Proportions in the model are illustrative.

How it's made

  1. Set
    Step 1

    Set

    The lower layers of one bracket set.

  2. Cap block
    Step 2

    Cap block

    Cap block: cross slot, 0.8 deep.

  3. Half-lap
    Step 3

    Half-lap

    Arm and projecting arm half-lap.

  4. Rule
    Step 4

    Rule

    Façade members cut on top, projecting members below.

  5. Crossing blocks
    Step 5

    Crossing blocks

    Crossing blocks carry the outer arms.

  6. Long arm
    Step 6

    Long arm

    The long arm goes on the centre arm.

Variations

Column-top set (柱头科)

Wider cap block (4 doukou) and projecting arms; the beam end replaces the top layers.

Corner set (角科)

Members change role around the corner, with diagonal arms along the corner line.

Sloping-tail set (溜金)

Inner tails rise along a slope and are pinned together with through-pins.

Can you CNC this?

Yes, with small changes

Every part is a block or a straight bar with square slots and half-lap notches cut from one face, ideal for 3-axis milling; curved arm ends are a 2D profile.

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 doukou?

The width of the cap block’s slot, used as the unit for every part.

Which member goes on top at a crossing?

The one running into the building: façade members are cut on top, projecting members underneath.

Is this the whole set?

No, only the lower layers are modelled.

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 238–239 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 232 页
  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 242–249 页