Loose Inserts#

Dowels, biscuits, & dominos as generated parts

Names: dowel biscuit domino

When to use#

Use a dowel, biscuit or domino joinery (or an edge_glue with biscuit_spacing) when two parts are joined by a loose piece glued into holes, slots or mortises cut in both. The compiler cuts both cavities and emits the loose piece itself. Do not model the dowel, wafer or domino as a stock part; it would be counted twice and reach the cut list.

Syntax#

No new syntax. The existing joinery nodes are unchanged:

• joinery dowel { diameter D; count N; depth H; clearance C } gives N round dowels, each D across and 2 * H long.
• joinery biscuit { size 0|10|20; spacing S } gives one #0 (47 x 15), #10 (53 x 19) or #20 (56 x 23) wafer, 4 thick, per whole S of the joint, at least one.
• joinery domino { size 4|5|6|8|10; spacing S; depth H } gives one loose tenon per whole S (size 8 is 8 x 22 x 40). depth defaults to half the tenon's length.
• edge_glue with biscuit_spacing and biscuit_size emits biscuits; without biscuit_spacing it emits nothing.

Each insert is a generated part, role=insert, in the male part's material, with id <male>@<mark>/Dowel_<i>, /Biscuit_<i> or /Domino_<i>. It is bought, not cut (ADR-0017): it appears in the scene, drawings, exploded views and clash check and in the hardware schedule (Dowel 8 x 24, Biscuit #20, Domino 8 x 22 x 40, quantity summed over every join), and in no cut list, stock list, cut card or toolpath.

Example#

project name="Doweled rail" units=mm schema_version=1 {
    materials { material Oak type=hardwood }

    component Post {
        stock Oak 38.0 38.0 130.0
        mark Face x=38.0 y=19.0 z=-65.0 normal=pos_x
    }
    component Rail {
        stock Oak 110.0 19.0 38.0
        mark End x=0.0 y=9.5 z=-19.0 normal=neg_x
    }
    joinery dowel name=Dowels {
        diameter 8.0
        count 2.0
        depth 20.0
        clearance 0.2
    }

    assembly Joint {
        part Post instance=Post { pos x=0.0 y=0.0 z=0.0 }
        part Rail instance=Rail { pos x=38.0 y=9.5 z=-46.0 }
        join joint=Dowels male=Rail@End female=Post@Face
    }
}

Compiling this gives two parts, Rail@End/Dowel_0 and Rail@End/Dowel_1, each a 8 x 40 round revolve straddling the joint plane, and two hardware rows' worth of purchased dowels (Dowel 8 x 40, quantity 2).

Pitfalls and diagnostics#

• Double counting. A hand-modelled stock dowel, wafer or domino beside the join is now a second piece; delete it.
• insert-fit (domino). 2 * depth shorter than the tenon's length leaves the tenon standing out of the mortises. Raise depth, or pick a smaller size.
• Clash. An insert overlapping its own joint's two parts is design interference, not a clash (RFC-0090 section 5). An insert that meets any third part, or overlaps its own parts beyond the tessellation budget, is reported as a clash. Two joints whose holes cross inside one part (a bottom rail's dominos and a stile's alignment biscuit slot, as in examples/bookcase.kdl) show up this way: it is a real modelling overlap.
• clearance is female-only (ADR-0012): the insert is nominal, fills the male cut and sits shy in the female one.
• Inserts are never in the cut list: a cut list is unchanged by adding or removing these joints.
• The hardware schedule label is the nominal size, so a #20 biscuit prints Biscuit #20.

See also#

• docs/KDL_AUTHORING.md section 8, "What the compiler cuts, and what it checks"
• docs/rfc/0140-loose-inserts.md, docs/adr/0023-loose-inserts.md
• docs/adr/0017-hardware-and-materials.md (bought, never cut), docs/adr/0018-turned-stock.md
• docs/styles/models/{dowel,biscuit,domino}-joint.kdl: the glossary's real joints

Names#

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

dowel#

joinery kind; value in 32 of 116 examples (54 uses).

Shortest real use, from tall_white_cutout_cabinet.kdl:

joinery dowel name=TopDowel {
    diameter 8.0
    count 3
    depth 18.0
    clearance glue_clearance
}

biscuit#

joinery kind; value in 1 of 116 examples (2 uses).

Shortest real use, from bookcase.kdl:

joinery biscuit name=TopEdgeGlue {
    size biscuit_size
    spacing biscuit_spacing
    clearance glue_clearance
}

domino#

joinery kind; value in 1 of 116 examples (1 uses).

Shortest real use, from bookcase.kdl:

joinery domino name=FrameCorner {
    size domino_size
    spacing domino_spacing
    depth domino_depth
    clearance glue_clearance
}

Related terms#

• Biscuit joint
• Domino joint
• Dowel joint