A file does not need to contain every production decision, but it should clearly represent the intended geometry and scale. Pairing the model with quantity, use and finish information gives the reviewer a much stronger starting point.
Choose a suitable file format
STL and OBJ describe the surface of a model as a mesh. STEP and STP preserve CAD geometry and can be useful when engineering features require closer review. A ZIP archive can group related files where permitted by the quotation form.
Export from the original CAD model where possible. Repeated conversions can introduce geometry errors or lose useful information.
Confirm units and scale
Mesh formats may not reliably carry unit information. State whether the model is designed in millimetres, centimetres or another unit, and include at least one known overall dimension. This makes scale assumptions visible before production.
Check that the geometry is printable
Look for open surfaces, non-manifold edges, intersecting bodies, inverted faces, zero-thickness features and accidental internal geometry. A model intended as a solid part should normally define a closed volume.
Review walls, holes and small details
Very thin walls, tiny text, narrow pins and small holes may not reproduce as expected. Practical minimums depend on the process, material, orientation and part size, so avoid treating one universal number as valid for every job.
Tell the reviewer which holes, mating faces, text or cosmetic surfaces are functionally important.
Plan for fit and assembly
Parts that slide, snap, bolt or nest together require intentional clearance. Perfectly coincident CAD surfaces do not create a reliable physical fit. Explain whether the assembly should be loose, sliding, press-fit or fixed.
Send the production context
- File units and a known dimension
- Quantity and whether parts are identical
- Intended use and environment
- Critical dimensions or mating features
- Material and finish preference
- Preferred completion date
- A drawing or reference image when it clarifies the requirement
Further reading
Technical limits depend on the selected process, machine and material. These manufacturer resources provide additional process-specific context:
Let’s review the actual part.
General guidance is useful, but geometry and intended use determine what is practical for a specific request.
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