5-Axis Machining — design guidelines
Five axes buy you two things: features on faces a 3-axis machine cannot see, and shorter tools on deep features because the head can tilt. What they do not buy is freedom from thinking about tool access — the holder still has to fit.
Constraints specific to this process
These are the limits that come from this process in particular. The general rules on wall thickness, corner radii and hole depth apply on top of them.
| Parameter | Design to thisNo surcharge, no discussion needed | We can reachAchievable, but affects price or lead time | Where the limit comes from |
|---|---|---|---|
| Holder clearance cone | 30° half-angle clear | 15° with slim holders | The tool tip may reach a surface while the holder collides with the wall beside it. Leaving a clearance cone around tilted surfaces is what makes 5-axis access real rather than theoretical. |
| Surface finish on a freeform face | Ra 1.6, 0.1 mm stepover | Ra 0.4, 0.03 mm stepover | A ball-nose cutter leaves scallops between passes. Halving the stepover halves the scallop height and doubles the cycle time — that trade is the whole cost of a mould-quality finish. |
| Features per setup | 5 faces in one clamping | 6th face needs re-grip | We can reach five faces from one grip, which removes the positional error between them entirely. The clamped face is the exception — plan which face that is. |
| True position across faces | 0.02 mm | 0.01 mm with probing | In one clamping the machine's rotary accuracy is the only error source. Hole-to-hole across two tilted faces at 0.02 mm is routine here and would need a jig bore on a 3-axis machine. |
What we see go wrong most often
Recurring issues on the drawings that reach us. None of them are hard to avoid once you know to look for them.
- Assuming 5-axis removes all draft and undercut limits. A feature enclosed on all sides still cannot be reached, no matter how the head tilts.
- Sending a mesh (STL) for a freeform surface. Toolpaths generated from facets leave visible facet edges — we need the exact surfaces from a STEP or Parasolid file.
General machining rules
The numbers that apply across every cutting process — wall thickness, radii, holes, threads, tolerances and cost drivers.
- Wall thickness
- Internal corner radii
- Holes and threads
- Pockets, cavities and undercuts
- Tolerances, text and surface callouts
- What actually drives the price
Every quotation includes a manufacturability review against these rules. If something in your model falls outside them, we tell you before you commit, not after the first article fails.
Not sure whether your part clears these limits?
Send the STEP file. A manufacturing engineer marks up anything that will be difficult and returns it with the quotation — no charge, no obligation.