Most rendering quotes for machinery go wrong at the same point: the CAD. A machine assembly of 4,000 parts that opens perfectly in SolidWorks or Creo can arrive in a render engine as a tangle of faceted surfaces, missing fasteners and a guard that sits 3 mm inside the frame. None of that is the engineer's fault. Engineering CAD is built to manufacture a machine, not to photograph it.
This guide explains what happens between your STEP file and a finished photoreal render, what you can do on your side to make the job faster and cheaper, and what a good rendering partner should handle for you. It is written from the workflow we use on every machine at 3DEnginuity, from single components to complete packaging lines.
Which CAD format should you send?
Send the format that carries the most information with the least conversion. In practice that means:
- STEP (AP214 or AP242) is the safest default. It keeps the assembly structure, part names and colours, and every serious render pipeline can read it. AP242 also carries product manufacturing information, which helps when parts have to be identified later.
- Native files (SolidWorks, Inventor, Creo, NX, CATIA) are welcome when the assembly is very large or uses configurations, because the structure survives intact. Send a pack-and-go archive so references are not broken.
- JT and Parasolid work well for big assemblies from Siemens and automotive suppliers.
- IGES works, but it often loses the assembly tree and arrives as loose surfaces. Use it only if nothing else is available.
- STL or OBJ are meshes, not CAD. They are fine for a single part, but a machine exported as one mesh loses its structure, so every guard and fastener has to be separated again by hand.
If you only have 2D drawings, a render is still possible. The geometry is rebuilt from the drawings first. We did exactly this for CeramOptec, where the fibre optic system existed only as 2D engineering drawings.
What happens to the CAD before rendering
Rendering software does not use the exact mathematical surfaces in your CAD. It converts them into triangles, a process called tessellation. Everything that follows is about making those triangles look as if they were machined, bent and painted by your workshop.
1. Tessellation at the right density
Too coarse and a round guard rail shows flat facets in a close-up. Too fine and a 4,000 part assembly becomes 80 million triangles that no workstation can light. A good pipeline tessellates per part: fine on visible curved surfaces such as rollers and hoppers, coarse on hidden brackets and internal plates.
2. Simplification and clean-up
Internal screws inside a closed drive housing, cable ducts behind panels and thousands of identical fasteners add weight but no visual value. They are removed or replaced with instances. Overlapping duplicate parts, which are common in exported assemblies, are deleted because they cause flickering surfaces in renders.
3. Fixing what the camera will see
Engineering assemblies often contain parts that are correct for manufacturing but wrong for a photograph: a door modelled open in one sub-assembly and closed in another, sheet metal without bend radii, or a polycarbonate guard modelled as a solid block. These are checked and corrected so the machine looks the way it does on the shop floor.
4. Materials, decals and colour
CAD colours are placeholders. Each visible material gets a physically based shader: brushed and bead-blasted stainless steel, powder coat with the correct gloss level, anodised aluminium, food-grade plastics, rubber belts, glass. Your RAL or Pantone colours are matched, and logos, warning labels and HMI screens are added as decals.
What you can do to make it faster and cheaper
A rendering studio can fix almost anything in the CAD, but every fix is billable time. These steps on your side typically save one to three working days on a machine project:
- Export the configuration you want to show. If the machine has options, export the one that sells. Tell us which variants matter and we can render the others later from the same prepared model.
- Remove confidential internals if you want to. If the camera will never see the gearbox internals or a patented mechanism, you can suppress them before export. It also reduces what has to be covered by the NDA.
- Include purchased parts. Motors, gearboxes, sensors and HMIs from suppliers are often missing from internal assemblies. Most suppliers publish free STEP files, so include them or send a list of part numbers.
- Send two or three photos of the real machine if one exists, even phone pictures. They answer questions about finishes, cable routing and labels that no CAD file can.
- Name the use. A website hero image, a 6 metre booth wall print and a spare parts catalogue need different resolutions and camera angles. Knowing this at the start avoids re-rendering.
How long CAD preparation takes
| Assembly | Typical parts | Preparation time |
|---|---|---|
| Single component (pump, valve, sensor) | 10 to 150 | Half a day to 1 day |
| Compact machine or module | 300 to 1,500 | 1 to 3 days |
| Complete machine with guarding | 1,500 to 6,000 | 3 to 6 days |
| Line of several machines | 6,000 to 40,000 | 1 to 3 weeks |
Preparation is the largest part of the first project for most machines, which is why it is included in every price on our pricing page rather than charged as a surprise extra. It is also why the second project costs less: the prepared model is kept on file, and each further render or animation from the same machine is typically 20 to 40 per cent cheaper.
Accuracy versus appearance
A render can be beautiful and wrong. For machinery, the most common errors are small: a pneumatic cylinder extended while the mechanism is closed, a belt on the wrong pulley, safety labels missing, cable chains that end in mid-air. They are invisible to a marketing team and obvious to your customer's engineers.
The fix is a review step by someone who reads assemblies. At 3DEnginuity every render is checked against the CAD and your references before you see it, and the look frame you approve shows the machine in the state it will be presented.
What you get back
A CAD to render project usually delivers more than images. Ask for these explicitly:
- Stills at web resolution and print resolution (4K and above for trade show walls).
- Transparent PNG cut-outs for brochures and configurators.
- The prepared, lightweight model as glTF or GLB if you plan a web 3D viewer or AR.
- A record of materials and colours so next year's renders match this year's.
How to check a render partner can handle your CAD
Before you send a full assembly, send one sub-assembly as a test. A capable studio should tell you within a day which formats it can read, what it found in the file (missing parts, broken references, duplicate bodies) and a fixed price. If the answer is a vague hourly rate, the CAD will probably become your problem halfway through the project.
Our $800 pilot project exists for exactly this reason: three photoreal renders of one component or compact product from your own CAD, delivered in three working days, so you can judge the result before committing to a full machine.
Written by Bilal Naseem, mechanical engineer and founder of 3DEnginuity. Questions about your own machine? Write to bilal.naseem@3denginuity.com.
Send one CAD file for a free assessment.
We open it, tell you what is usable, and return a fixed price and delivery date within one working day. NDA first if you need it.
