How to Export STL Files from Rhino for 3D Printing Jewelry

Why Getting Your STL Export Right Matters

You've spent hours perfecting a cabochon bezel, a halo ring, or a custom engagement band in Rhino — the last thing you want is a failed print because of mesh errors or the wrong export settings. Getting your STL export right the first time saves money, protects your client relationships, and keeps production moving. This tutorial walks you through every step, from meshing your polysurface to sending a clean file to your caster or print bureau.

Step 1: Check Your Model Before You Mesh

Before exporting, run a quick health check on your Rhino model:

• Type ShowEdges and look for naked edges (shown in magenta). These indicate open surfaces that will cause problems in STL.
• Use Check to confirm your object is a valid closed polysurface (solid). A closed solid is required for a watertight print-ready STL.
• Make sure your model is built to real-world scale in millimeters. Most casters and print services expect mm units.

Step 2: Set Rhino Units to Millimeters

Go to File → Properties → Units and confirm your document is set to millimeters. If you modeled in inches, you can convert: type Scale, set the scale factor to 25.4, and scale your entire model. Double-check wall thicknesses — ring shanks should be at least 1.2–1.5 mm for casting, and prongs at least 0.8 mm.

Step 3: Mesh Your Polysurface

STL is a mesh format, so Rhino converts your NURBS surfaces to triangles at export. The quality of this mesh determines print resolution.

1. Select your object and go to File → Export Selected.
2. In the file type dropdown, choose STL (Stereolithography).
3. Click Save. Rhino will prompt you with Polygon Mesh Options.

Recommended settings for jewelry:

• Jagged & Faster is too coarse for jewelry — avoid it.
• Use Smooth & Slower as a starting point, then click Detailed Controls.
• Set Maximum distance, edge to surface to 0.01 mm for high detail.
• Set Maximum angle to 10–15 degrees.
• Enable Simple planes to keep flat faces clean.

Step 4: Choose Binary vs. ASCII STL

When prompted, choose Binary. Binary STL files are significantly smaller than ASCII and are accepted by all modern slicers and casting bureaus. ASCII is only useful for debugging.

Step 5: Verify the STL Before Sending

Always inspect your exported STL before sending it to production. Free tools for this include:

• Meshmixer (free, by Autodesk) — run Analysis → Inspector to find and auto-repair holes.
• Netfabb Basic — industry-standard repair tool.
• Magics
• PrusaSlicer or Chitubox — if your bureau uses resin printing, preview the file in their slicer to check supports and wall integrity.

Look for: inverted normals, non-manifold edges, and shells that aren't connected. Any of these will cause a failed or distorted print.

Step 6: Communicate With Your Print Bureau

Different casting and print services have their own requirements. Before sending your first file to a new bureau, ask:

• What minimum wall thickness do they require for their specific process (resin, wax, direct metal)?
• Do they prefer binary STL, OBJ, or 3DM?
• What resolution setting do they recommend?
• Do they offer a preflight check?

Building a clear file-handoff checklist saves revision rounds and builds trust with your clients.

Common STL Export Mistakes in Jewelry CAD

• Open surfaces — always close your model before exporting.
• Mesh too coarse — curves look faceted in the final print. Use 0.01 mm tolerance.
• Wrong scale — exporting in inches when the bureau expects mm is one of the most common (and costly) errors.
• Ignoring wall thickness — thin prongs or shanks may look fine on screen but fail during casting.

Take Your Rhino Skills Further

Mastering STL export is one piece of a professional jewelry CAD workflow. If you're looking to deepen your Rhino skills — from bezel settings and halo designs to full custom CAD modeling for client orders — explore our Rhino jewelry CAD models and resources. Our membership also includes access to live sessions and community support for working jewelry designers and studios.