Disclosure: Published on behalf of CADProps. This original guide was prepared with AI assistance and checked against the linked documentation. The numerical example is an analytical illustration, not a reported software test.

A useful CAD intake check should leave a record another person can repeat. “It opened successfully” is a weak handoff: it does not say which revision arrived, which components loaded, or whether the reported dimensions describe the intended part.

Here is a compact workflow for checking a received STEP model before using its properties in a quote or review. It is a proposed intake procedure, not a manufacturing acceptance standard.

1. Record the question before opening the file

Write down the decision you need to make. “Confirm the envelope of the mounting plate” and “estimate the mass of the complete assembly” require different scope. Record the filename, revision supplied by the sender, receipt date and expected component count. Keep the received file unchanged.

For sensitive geometry, confirm that your organization permits the chosen processing location before uploading anything. A browser interface does not establish that processing stays on your device.

2. Establish scope, then scale

Compare the imported structure with the expected parts. Note missing references, suppressed or omitted components and any incomplete-import warning. Do not silently treat a partial assembly as the complete product.

Check one known dimension against a drawing or a value supplied by the designer. Use a feature that can be identified unambiguously, such as a documented hole diameter. Record the displayed unit alongside the number. A bounding box can help catch gross mistakes, but it does not replace a feature measurement: its extents depend on the model's orientation relative to the axes.

If a value disagrees, pause and resolve the import or unit assumption. Do not scale the geometry merely to make one number agree while leaving the cause unexplained.

3. Separate visual appearance from volume evidence

A shaded object can look solid even when the imported representation is unsuitable for an enclosed-volume calculation. Read the geometry warnings and establish whether you have valid closed solids before using volume for mass.

The Open CASCADE BRepGProp reference documents distinct choices for using surface geometry or triangulations and for restricting calculations to closed shells. This illustrates why a number needs calculation context; a volume field alone is not a validity certificate.

For an assembly, label what the total means. A sum of component volumes and the volume of their geometric union answer different questions when components overlap. Record whether repeated occurrences are included and avoid calling an occurrence sum the union volume.

4. Use a simple analytical check when appropriate

Consider a hypothetical rectangular plate, 60 × 40 × 10 mm, with one straight through-hole of diameter 6 mm perpendicular to its large faces. Assume no chamfers, fillets or other features.

Uncut block volume = 60 × 40 × 10 = 24,000 mm³.

Removed cylinder volume = π × 3² × 10 = 90π mm³.

Expected plate volume = 24,000 − 90π ≈ 23,717.26 mm³.

This constructed example provides an independent arithmetic check for that exact geometry. It says nothing about the accuracy of an arbitrary production model or any particular viewer. A real plate with edge breaks or extra holes should not be expected to match it.

If an assumed uniform density is 2.70 g/cm³, the example's estimated mass is:

23,717.26 ÷ 1,000 × 2.70 ≈ 64.04 g.

Density here is an illustrative input, not proof of material grade. Record the source of the real density and distinguish a solid-material estimate from an infilled printed part's mass.

5. Leave an inspection log that preserves uncertainty

A practical record can use these fields:

File and supplied revision:

Question being checked:

Expected scope / loaded scope:

Tool and date:

Geometry representation and warnings:

Known dimension / observed value / units:

Property scope (selected part, occurrence sum or union):

Volume and units:

Density assumption and source, if used:

Unresolved discrepancy:

Next action and responsible reviewer:

For a discrepancy, keep the observed value instead of replacing it with the expected one. Attach a screenshot only if it helps identify the selected feature; a screenshot without selection context can be ambiguous.

Optional tool

CADProps can be used for browser-based viewing and available measurements. Its published specifications state that uploaded CAD files are processed on its servers; exact or approximate results depend on the geometry and format, and incomplete results can restrict available properties. Check those conditions before choosing it for a particular file:

https://www.cadprops.com/specifications/

For the tool's STEP-specific opening workflow:

https://www.cadprops.com/guides/step-file-what-it-is-how-to-open/

Technical reference

Open CASCADE Technology, BRepGProp class reference:

https://www.occt3d.com/dev/doc/refman/html/class_b_rep_g_prop.html

The goal of this log is modest: make a preliminary geometry check repeatable and make its limitations visible. It does not replace the drawing, agreed inspection procedure or engineering approval.

A reproducible STEP intake check: scope, scale and a useful inspection log