PCB Enclosure & Test Bench Generator

This project is a parametric CAD generator that creates 3D printable enclosures and test benches/fixtures directly from PCB SVG outlines.

Built using CadQuery and svgpathtools, this tool analyzes 2D SVG layers (distinguished by stroke color) to generate complex, sweeping 3D geometry.

Features

• Parametric Generation: Fully adjustable dimensions (wall thickness, PCB thickness, clearances, screw sizes) via CLI arguments.
• SVG-Driven Design: Define the geometry and special features (clips, screws, supports) visually in your vector graphics editor (e.g., Inkscape, Illustrator) using color codes.
• Interlocking Box Design (box.py):
  • Generates two halves (inner/outer) that slide/snap together.
  • Supports custom profiles: Z-profile (locking step), C-profile (chamfered), and S-profile (simple notch).
  • Automatic PCB slot generation and support structures.
• Test Bench / Jig Design (bench.py):
  • Pogo Pin Testing: Generates a mounting plate with precise holes for pogo pins (spring-loaded contacts).
  • Clamping Mechanism: Generates mounts for ballscrews or clamps to apply pressure, ensuring reliable electrical contact between the PCB and pogo pins.
  • Easy Extraction: Automatically generates wall cutouts ("fingers") to allow users to easily grab and remove the PCB from the fixture.
  • Fabrication Ready: Exports both 3D models (STEP) and 2D fabrication files (SVG).

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Requirements

• Python 3.x
• CadQuery
• numpy
• svgpathtools
• shapely

pip install cadquery numpy svgpathtools shapely

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1. SVG Input Specification

The tools rely on Stroke Color to identify different parts of the PCB geometry. Ensure your SVG uses the following hex codes for stroke colors.

For Box Generator (box.py)

Feature	Color	Hex Code	Description
Outline	Black	#000000	The main perimeter of the PCB that use the S-profile (simple notch).
Anchor	Red	#ff0000	Segments of the perimeter that use the Z-profile (locking step).
Clip	Green	#00ff00	Segments of the perimeter that use the C-profile (chamfered/snap).

Note: Any segment not marked as Anchor or Clip will default to the standard Outline profile.

For Bench Generator (bench.py)

Feature	Color	Hex Code	Description
Outline	Green	#00ff00	The main perimeter of the PCB.
Support	Red	#ff0000	Support pillars underneath the PCB.
Hole	Black	#000000	Cutouts or holes through the bench base.
Filler	Blue	#0000ff	Guide pins/columns protruding through PCB holes.
Screw	Magenta	#ff00ff	Locations for ballscrew/clamp mounts to press the PCB against pogo pins.
Finger	Cyan	#00ffff	Cutouts in the wall to allow fingers to easily grasp and remove the PCB.

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2. Generating an Enclosure (box.py)

Generates a 2-part interlocking case.

Usage

python box.py [options] input.svg output_file.step

Key Arguments

Argument	Flag	Default	Description
SVG Input	(Positional)	N/A	Path to the PCB SVG input file.
Output File	(Positional)	N/A	Path to the output file (e.g., .step or .stl).
Log Verbosity	-v, --verbose	0	Increases log verbosity for debugging.
PCB Thickness	-t, --pcb-thickness	$1.6$	Thickness of the PCB in mm.
PCB Z-Offset	-z, --pcb-z	$1.2$	Vertical offset (Z-axis) of the PCB's center plane relative to the junction center in mm.
PCB Clearance	-w, --pcb-clearance-offset	$0.15$	Clearance distance (in mm) between the PCB outline and the surrounding enclosure walls/slots.
PCB Cover Offset	-u, --pcb-cover-offset	$0.4$	Distance (in mm) the internal support lip extends over the surface of the PCB edge.
PCB Support Angle	--pcb-support-angle	$45.0$	Angle (in degrees) of the slanted internal support lip holding the PCB.
Disable PCB Features	--disable-pcb	False	If set, prevents the generation of internal PCB features (slots, supports).
Wall Thickness (Min)	-n, --wall-thickness	$0.88$	Minimum wall thickness (in mm).
Wall Offset	-o, --wall-offset	$-0.4$	Offset distance (in mm) applied to the PCB outline to determine the inner wall perimeter. Negative values move the wall inward.
Wall Extra Height	-m, --wall-extra	$1.5$	Extra wall height (in mm) extending above and below the main junction line.
Junction Height	-y, --junction-height	$2.0$	Total height (in mm) of the section between the two interlocking box halves.
Junction Width	-x, --junction-width	$1.0$	Horizontal width (in mm) of the section between the two interlocking box halves.
Junction Flipped	-f, --junction-flipped	False	Flips the junction profile, reversing the inner/outer lip placement.
Z-Profile Angle	--z-angle	$30.0$	Angle (in degrees) used for the slanted edge of the Z-profile junction.
C-Profile Angle	--c-angle	$60.0$	Angle (in degrees) used for the chamfered edge of the C-profile junction.
SVG Scale Factor	-s, --scale	$0.264583$	Scaling factor to convert SVG coordinates to working units (mm).
Mechanical Play	-p, --play	$0.10$	Mechanical clearance (tolerance) applied between interlocking parts/features in mm.

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Example

python box.py -s 1.0 box.svg box.step

File Name	Description	Image
box.svg	The 2D input outline used to generate the CAD model.
box.step	The resulting 3D model of the complete enclosure.
box.step	Cross-section view showing the locking Z-profile and chamfered C-profile.
box.step	Cross-section view showing the simple notch S-profile.

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3. Generating a Test Bench (bench.py)

Generates a rugged mounting plate/jig designed for manufacturing tests or flashing.

Usage

python bench.py [options] input.svg output_file.step

Key Arguments

Argument	Flag	Default	Description
SVG Input	(Positional)	N/A	Path to the PCB SVG input outline file.
Output File	(Positional)	N/A	Path to the output file (e.g., .step or .stl).
Log Verbosity	-v, --verbose	0	Increases log verbosity for debugging.
PCB Thickness	-t, --pcb-thickness	$1.6$	Thickness of the PCB in mm.
Base Plate Thickness	-b, --bottom	$8.0$	Thickness (in mm) of the main bench base plate.
Under PCB Space	-u, --under-space	$5.0$	Vertical clearance (in mm) between the bottom of the PCB and the top of the bench base plate.
Pogo Pin Diameter	-d, --pin-diameter	$0.95$	Diameter (in mm) for the pogo pin holes.
Wall Thickness (Side)	--wall-thickness	$2.0$	Thickness (in mm) of the protective side walls surrounding the PCB.
Wall Fillet	--wall-fillet	$2.0$	Fillet radius (in mm) applied to the side wall corners.
Wall Height	--wall-height	$5.0$	Height (in mm) of the protective side walls.
Wall Play	--wall-play	$0.4$	Lateral clearance (in mm) between the PCB perimeter and the walls.
Filler Pin Height	--filler-height	$5.0$	Height (in mm) of the guide pins/columns (Fillers, Blue SVG) protruding through PCB holes.
Fixture Screw Hole Dia.	--fixture-screw-hole	$2.8$	Diameter (in mm) for the hole that mounts the fixture clamping mechanism.
Fixture Screw Boss Dia.	--fixture-screw-diameter	$5.0$	Outer diameter (in mm) of the boss/standoff feature for the clamping mechanism.
Fixture Screw Z-Offset	--fixture-screw-offset	$0.5$	Z-offset (in mm) of the clamp's contact surface relative to the top surface of the PCB.
Fixture Screw Extra Wall	--fixture-screw-extra	$3.0$	Extra wall thickness (in mm) added to reinforce the fixture screw boss/standoff.
Support Fillet	--support-fillet	$1.0$	Fillet radius (in mm) applied to the top edges of PCB support features.
Filler Fillet	--filler-fillet	$0.5$	Fillet radius (in mm) applied to the top edges of filler/guide pins.
Extra Fillet Level	--extra-fillet	$4$	Enables or sets the size/iteration of extra, secondary fillets applied to global features.
Box Wall Thickness	--box-wall-thickness	$2.0$	Thickness (in mm) of the walls/standoffs used for mounting the entire test bench assembly.
Box Screw Diameter	--box-screw-diameter	$2.45$	Diameter (in mm) of the screw holes for mounting the entire test bench assembly.
Box Screw Offset	--box-screw-offset	$1.00$	Depth (in mm) of the counterbore or screw head cavity relative to the top of the mounting plate.
SVG Scale Factor	-z, --scale	$0.264583$	Scaling factor to convert SVG coordinates to working units (mm).
Mechanical Play	-p, --play	$0.15$	Mechanical clearance (tolerance) applied between manufactured parts/features in mm.
Mirrored	-m, --mirrored	False	If set, mirrors the SVG geometry along the X-axis (top-bottom flip).

Example

python bench.py -vvvvvv -m jig.svg jig.step

File Name	Description	Image
jig.svg	The 2D input outline used to generate the CAD model.
jig.step	The resulting 3D model of the complete test bench/jig.

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Technical Details

Scaling Note

SVG editors (like Inkscape) and PCB CAD software exporters (like Altium's SVG output) often handle units differently, requiring a scaling factor to convert the graphic's units (usually pixels) into the working units (millimeters) required by the generator.

If your dimensions are incorrect, you must check your SVG DPI settings (in your editor or your PCB CAD software's export options) or adjust the scale argument (-s or -z).

• The default scale factor of $0.264583$ assumes the SVG uses pixels based on the 96 DPI standard (common in Inkscape and often the default for modern exports like Altium's).
  • 1 px @ 96 DPI = $0.264583$ mm.
• If your SVG editor or exporter uses 72 DPI (an older or different standard), the correct scale factor is $0.352778$.
  • 1 px @ 72 DPI = $0.352778$ mm.