Features

Features are cut into a part’s blank. They do not change the blank’s size: a dado does not shorten a board and a tenon does not lengthen one. The blank is what you buy; the features are what you do to it.

parts:
  - id: head_post
    blank: { length: 900, width: 75, thickness: 75 }
    features:
      - kind: groove
        id: panel_slot
        on: right
        along: length
        width: 18
        depth: 10
        center: true
        stopped: 40
      - kind: chamfer
        edges: [end_*]
        size: 3

Every feature takes an optional id. Give it one if a joint needs to mate to it — that is what turns the feature into an anchor, and it is how a panel and the groove it sits in stay in step.

Most features also take an on: face. Faces, edges and the (u, v) frames they are measured in are all on the Anchors page.

Positioning along an axis

Dados, grooves, mortises and notches sit somewhere along an axis, and there are four ways to say where. Give exactly one.

Form	Means
from: 120	120 mm from the start end to the feature’s near edge
to: 300	300 mm from the start end to the feature’s far edge
at: 210	210 mm from the start end to the feature’s centre
center: true	Centred on the axis

Giving two, or none, is a RES- finding rather than a guess. The resolver will not pick for you, because picking wrong puts a trench in the wrong place and nothing downstream would notice.

from and to may be expressions, so a feature can follow a parameter:

- kind: dado
  on: right
  from: deck_height - shelf_stock.thickness
  width: 18
  depth: 9

The trenches

dado

A square-bottomed trench across the grain, running the full width of the face unless stopped.

- kind: dado
  id: shelf_seat
  on: right
  along: width        # optional — defaults to the short axis of `on`
  at: 400
  width: 18           # the width of the trench, i.e. the thickness of what sits in it
  depth: 9
  stopped: 12         # optional: stop 12 mm short of the far edge

width is the trench’s width, not the part’s. Size it to the thickness of the part that seats in it — or better, reference that part directly:

width: shelf.blank.thickness

groove

The same cut, with the grain. It is a separate kind because the validation differs: a groove along the grain and a dado across it fail in different ways, and a groove is what captures a panel that will move seasonally.

Same keys as dado. stopped: leaves a blind end, which is what keeps a groove from showing on the front edge of a post.

rabbet

An L-shaped cut along one edge of a face.

- kind: rabbet
  id: back_seat
  on: right             # one of the six faces
  edge: end             # which edge of that face it runs along
  width: 12
  depth: 9
  from: 0               # optional — run only part of the edge
  to: 400

Note edge: here names an edge of the face, not one of the twelve blank edges.

mortise

A blind or through rectangular slot.

- kind: mortise
  id: tenon_seat
  on: right
  along: length         # the slot's long axis
  at: 300
  length: 60            # along `along`
  width: 12             # across it
  depth: 30             # omit and set `through: true` for a through mortise
  ends: round           # `round` (routed) or `square` (chiselled)

ends matters to whoever cuts it: a router leaves round ends and a chisel leaves square ones, and a tenon has to match whichever you chose.

notch

A rectangle removed from a corner or an edge — the classic leg-and-apron cut-out.

- kind: notch
  on: top
  edge: start
  from: 0
  length: 40
  depth: 20

Holes and pockets

hole

- kind: hole
  on: top
  diameter: 8
  depth: 12             # or: through: true
  at: { u: 100, v: center }
  counterbore: { diameter: 14, depth: 7 }
  countersink: { diameter: 8.4, angle: 90 }

at is a position in the face’s own (u, v) frame, measured from its minimum corner. Either value may be center.

For more than one hole, use pattern: instead of at: — see below.

Most holes should not be authored. Every clearance hole, pilot hole, counterbore and countersink that belongs to a fastener comes from the fixture’s machining recipe when you declare a joint. Hand-placing a screw hole means the validator cannot check its edge distance or thread engagement, because as far as it knows there is no screw there. Author a hole for a cable exit, a bolt you are supplying yourself, or a shelf-pin array — not for a screw.

pocket

A flat-bottomed rectangular recess that reaches no edge.

- kind: pocket
  on: bottom
  length: 120
  width: 40
  depth: 6
  at: { u: center, v: center }

Patterns

A repeated position. This is the shape behind every run of screw holes and every shelf-pin line.

pattern:
  along: length         # required: which axis the run follows
  count: 10
  spacing: auto         # centre-to-centre, or `auto` to divide the span evenly
  margin: 80            # keep this clear at each end

Key
along	Required. length, width or thickness.
count	How many. An expression, so it can be computed.
spacing	Centre-to-centre, or auto to divide the available span evenly.
margin	Clear space to leave at each end of the span.
from / to	Bound the run explicitly instead of using the whole axis.
center	Centre the run on the axis.
offset	Position on the face’s other axis. Defaults to centred.
at	Shorthand instead of count and spacing: any of start, end, centre, ends.

# Ten screws down a cleat, evenly spread, 80 mm clear at each end.
pattern: { along: length, count: 10, spacing: auto, margin: 80 }

# Two bolts, 100 mm apart, positioned at a computed height.
pattern:
  along: length
  count: 2
  spacing: bolt_pitch
  from: rail_centre_height - bolt_pitch / 2
  to:   rail_centre_height + bolt_pitch / 2

# Shelf pins on the 32 mm system.
pattern: { along: length, count: 12, spacing: 32, from: 200 }

The same pattern shape is used by joints[].fasteners.pattern, which is where you will write it most of the time.

Edge treatments

chamfer and roundover

Both take edge selectors, and wildcards work:

- kind: chamfer
  edges: [top_end, bottom_end, left_end, right_end]
  size: 3

- kind: chamfer
  edges: [end_*]        # the same four, shorter
  size: 3

- kind: roundover
  edges: [top_left, top_right]
  radius: 3

Edge names and the wildcard rules are on the Anchors page. A chamfer or roundover has no frame, so it cannot be mated to.

A 2–3 mm break on every edge a hand will touch is worth authoring. It is also the cheapest thing in the file to change later.

taper

A linear taper of one dimension along another axis — table and chair legs.

- kind: taper
  along: length         # the axis the taper runs down
  reduce: width         # the dimension that shrinks
  to: 30                # its size at the far end of `along`
  from: 150             # where the taper begins, from the `start` end
  sides: both           # `both` (default), `near` or `far`

sides: far tapers only the outward face, which is the usual choice for a leg that must stay square where it meets an apron.

The ten kinds, at a glance

Kind	Positioned by	Mateable
dado	on + along-axis form	yes
groove	on + along-axis form	yes
rabbet	on + edge + from/to	yes
mortise	on + along-axis form	yes
hole	on + at or pattern	yes
pocket	on + at	yes
notch	on + edge + along-axis form	no
chamfer	edges	no
roundover	edges	no
taper	along + reduce	no