Good CNC design keeps parts strong, accurate and affordable. These rules of thumb apply to most milled and turned parts.
Key Design Rules
| Feature | Recommendation | Why |
|---|---|---|
| Internal corners | Radius slightly larger than the cutter radius | Avoids slow, small tools and dwell marks |
| Pocket depth | Up to about 4× the pocket width | Long tools deflect and chatter |
| Wall thickness | Metals ≥ about 0.8 mm, plastics ≥ about 1.5 mm | Thin walls vibrate and deform |
| Holes | Use standard drill sizes; depth up to about 4–10× diameter | Standard tools are faster and cheaper |
| Threads | Thread length up to about 3× diameter | Extra length adds little strength |
| Text and engraving | Engraved rather than embossed, sans-serif font | Less material removal |
Features That Increase Cost
- Tight tolerances on non-functional dimensions
- Deep, narrow cavities and sharp internal corners
- Features requiring multiple setups (consider 5-axis)
- Very thin walls and tall unsupported features
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