How to prepare your CAD file for 3D printing

Clean parts begin with a clean file. Roughly half the models sent to us need one small correction first — usually a five-minute job once you know where to look. Below is the same checklist our engineers apply to every order.

1. Make it watertight

Your mesh has to be a sealed solid — no gaps, no flipped faces, no stray interior walls. Nearly every CAD package ships a repair or analysis tool, so run it before exporting. When the slicer preview shows holes or odd voids, fix the mesh rather than blaming the machine.

2. Respect minimum walls

As a working rule, hold walls above 0.8 mm in FDM, 0.5 mm in SLA resin and 0.7 mm in SLS nylon. Walls joined on both edges can run thinner than freestanding ones. Keep raised text and embossing at least 0.6 mm tall so it survives cleanup.

3. Design in tolerances

Fitting parts need air: allow 0.2 mm per side for FDM slip fits, 0.1 mm for SLA, 0.15 mm for SLS. Bores tend to print a touch small, so enlarge holes by 0.1–0.2 mm or schedule a fast drill pass where the fit is critical.

4. Export at the right resolution

Send STL or 3MF (our preference) with chord tolerance near 0.01 mm. Coarser settings facet your curves; finer ones balloon the file for no visible gain. Native STEP files work well too — share those whenever you have them.

• Units set to millimetres with the model built at true 1:1 size.
• Key dimensions and thread callouts added to the order notes.
• Assemblies oriented as used, or divided for printing when oversized.