Grain Axis#

Pinning a part's grain direction to a named axis

Names: stock along_x along_y along_z

When to use#

Use along_x, along_y or along_z on a rectangular stock line when you know which way the grain runs and the board's proportions can change. lengthwise and crosswise are re-derived from the board's current dimensions at every parameter value, so a parametric panel whose depth and height can cross over silently turns its grain 90 degrees, and every dado and groove on it turns with it. A drawer side or a chest end is the usual case: the grain runs front to back (or along the end's length) whether the part is wider than tall or not. Pin it and the grain stays put.

Leave lengthwise (the default) on members and fixed-proportion parts. Sheet goods (type=sheet) have no grain; naming one is still an error.

Syntax#

stock <Material> x y z [grain], where grain is one of:

The axes are the part's own D4 frame, before placement; a rotation or mirror in pos does not change which local axis is pinned. It is a bare word in the fifth positional slot, not a CEL expression and not a named property (grain=y is rejected, ADR-0007 rule 4).

Effects of a pinned axis:

• ADR-0011 rule 2 reads it directly: a groove runs along it and a dado across it. A cut into a face whose normal is the pinned axis is end grain and is skipped, with that reason shown.
• The cut list and part cards put the pinned axis first: its length is L (runs with the grain), even when another dimension is larger. The grain line reads along_y.
• There is no tie error: a board with two equal long dimensions is fine once pinned.

Example#

// A drawer side 278 mm deep and 312 mm tall: taller than it is deep, so the default
// `lengthwise` would run the grain up the side and turn the bottom groove vertical.
// Pinned along_y, the grain and the groove run front to back at every setting.
project name="Pinned Grain Side" units=mm schema_version=1 {
    params {
        side_d 278.0 min=200.0 max=400.0 step=1.0 label="Side Depth"  category="Envelope"
        side_h 312.0 min=100.0 max=400.0 step=1.0 label="Side Height" category="Envelope"
    }

    materials {
        material WhiteOak type=hardwood
    }

    assembly Root {
        part Side material=WhiteOak role=drawer_side {
            stock WhiteOak 15.0 side_d side_h along_y
            groove width=6.0 depth=6.0 offset=10.0
            by top_sw
            pos x=0.0 y=0.0 z=0.0
        }
    }
}

Pitfalls and diagnostics#

• It is one axis for the whole board, not grain per face. A quadrilinear post (four mitred quartersawn boards round a core) still cannot say that each face shows the same figure; docs/styles/models/quadrilinear-leg.kdl stays approximate for that reason (per-face grain is not in the language; RFC-0113, grain on turned stock, is still open).
• Pinning the thickness axis makes the broad faces end grain (a butcher-block end): every dado/groove on those faces is skipped as end grain, by design.
• Do not pin out of habit. A leg or rail that never changes proportion gains nothing; the default already reads its longest dimension. Pin parametric panels whose depth and height ranges overlap.
• Round stock (stock <Mat> shape=round ...) takes no grain word at all: its grain is derived, along the turned axis. The pinned words are for rectangular stock.
• ww-expand rejects any other word: grain is `lengthwise`, `crosswise`, `along_x`, `along_y` or `along_z` . A grain word of any kind on a type=sheet material is the error "<Mat> is a sheet material and has no grain".

See also#

• docs/rfc/0072-grain-pinned-to-an-axis.md, docs/adr/0028-grain-pinned-to-an-axis.md
• docs/adr/0011-dado-and-groove-placement.md (rule 2), docs/adr/0007-stock-line.md
• docs/KDL_AUTHORING.md section 10, house rule 4
• examples/bedside_cabinet.kdl, examples/blanket_chest.kdl, examples/six_board_chest.kdl, examples/biedermeier_box.kdl

Names#

Every name this page declares, how the example library uses it, and the shortest real use.

stock#

feature; node in 114 of 116 examples (910 uses).

Shortest real use, from glazed_vitrine_whiplash_crest.kdl:

stock Glass dw 6.0 dh

along_x#

grain; value in 35 of 116 examples (133 uses).

Shortest real use, from kumiko_andon_lantern.kdl:

stock Hinoki wo pan_th prh along_x

along_y#

grain; value in 25 of 116 examples (34 uses).

Shortest real use, from shaker_tall_chest_of_drawers.kdl:

stock Poplar box_th box_d h along_y

along_z#

grain; value in 27 of 116 examples (44 uses).

Shortest real use, from kumiko_andon_lantern.kdl:

stock Hinoki sw pan_th ph along_z