parametric-junctionbox
A parametric electrical junction box in OpenSCAD: a rounded box with cable-gland holes in its walls, a screw-down lid, and two accessories, a reducer bushing for a gland and a blocker for an unused hole. Set the size, wall thickness and the number of gland holes on each side, and pick the part to render.
Use it
Open junctionbox.scad in OpenSCAD, edit the
parameters at the top, and set part:
part |
What it makes |
|---|---|
"box" (default) |
The box, 100 × 100 × 50 mm by default. |
"lid" |
The lid, as thick as the walls, with a screw hole at each corner. |
"bushing" |
A slit sleeve that fits in a gland to grip a thinner cable: bushing_od, bushing_id, bushing_length, bushing_slitangle. |
"blocker" |
A friction-fit plug for a gland hole you don’t use. |
"none" |
Nothing, for when you include this file in another. |
The main parameters:
| Parameter | Default | Description |
|---|---|---|
junctionbox_width, _height, _thickness |
100, 100, 50 | Outside size in x, y and z, in mm. |
junctionbox_skin |
3 | Wall, floor and lid thickness. |
junctionbox_radius |
8 | Corner radius; the lid-screw pillars are twice this across. |
junctionbox_cablediam |
20.5 | Gland hole diameter, for M20 glands. |
nh, sh, wh, eh |
2 each | Gland holes in the north (+y), south, west (−x) and east walls, each centred in an equal share of the wall between the corner pillars. A count whose holes would overlap is refused, with the most that fit. |
junctionbox_lidscrewdiam |
3 | Lid screw holes, for M3 × 12 self-tapping screws. |
junctionbox_mountscrewdiam, junctionbox_mountoffset |
3, 20 | Four holes in the floor for fixing the box to a surface, this far in from each edge. |
The box isn’t watertight as printed. A bead of silicone on the rim before fitting the lid may seal it, and the floor’s mounting screws would need sealing washers.
Checks
just test takes about 1 s on OpenSCAD 2026.10.15. It renders each part and
checks its size, and that it’s one piece standing on z = 0. It counts the holes
in each wall with different counts per side, measures the floor holes at two
offsets, and checks that an unknown part, and four holes along a 100 mm
wall, are refused. just images renders
the picture above; it needs ImageMagick’s montage.
Origin and licence
The box is a rewrite, under MIT, of an idea from Adam Oellermann’s Parametric Electrical Junction Box: a rounded box with gland holes, a screwed lid, a reducer bushing and a blocker. The code is new; the parameters and parts keep their names, so existing settings still work. The earlier GPL-3.0-or-later versions are in this repository’s history. MIT; see LICENSE.