# Conceptual shock-isolation CAD

Original parametric geometry created for DMGB Systems on 2 October 2026. This is a replacement teaching illustration, not a reconstruction of an externally sourced device or proof of the previous raster's provenance. No reference image was traced.

The editable CadQuery script produces six boundary-representation solids: a moving base, an inert supported mass, two helical springs, and a damper body and rod. STEP retains the named assembly and colours. The PNG/PDF views are tessellations of those same solids. The square hero has no embedded text; supply its legend, explanation and limitations as accessible HTML.

## Meaning and limits

The cyan block represents an inert mass; purple springs represent elastic energy storage; the gold damper represents mechanical energy dissipation; the blue base represents imposed motion. The two springs are a visual representation of a combined elastic support, not two independently calculated stiffness values. Springs and damper act in parallel in the teaching concept.

All dimensions are arbitrary drawing coordinates stored as millimetres for exchange. Mass cannot be inferred without density, and stiffness or damping cannot be inferred from these shapes. Connections, bearings, spring end seats, stroke stops, internal damper hardware, friction, stress, material choice, tolerances, preload and realistic guidance are omitted. The helical ends intersect the base/mass symbolically; this is not a manufacturable assembly. No force, damping coefficient, natural frequency or safe operating range is specified. The geometry is not coupled to the chapter calculator and is not a tested isolator.

## Rebuild

Install Python, cadquery==2.7.0 and matplotlib, then run `python build_shock_cad.py`. In the current project environment, the available CadQuery distribution is `tmp/cad-prep-cadquery-2.7-deps`; set PYTHONPATH to its absolute path before running. That local runtime is not part of this downloadable asset.

Outputs: `shock-isolation-concept.step`, `components.csv`, `validation.json`, `shock-isolation-cad-wide.png/.pdf`, `shock-isolation-cad-mobile.png/.pdf`, and `shock-isolation-cad-hero.png`. The source script is the editable parametric model; STEP is a neutral solid exchange file, not native Fusion history.

## Validation

All six original solids and all six reimported STEP solids have valid topology and positive volume. Total reimported volume agrees within a relative tolerance of 1e-8. Exact values, parameters and STEP SHA-256 are recorded in validation.json. This checks geometry and exchange integrity only; no mechanical performance or experimental validation is implied. Rendered mobile and hero views were inspected for visible geometry and legibility (HTML accessibility requires separate page testing).