Nexus CNC Accuracy: How to Verify It Before You Order

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  What matters most when you judge accuracy
• 2
  Accuracy criteria: what to ask and what good looks like
• 3
  Reading a Nexus CNC accuracy claim correctly
• 4
  Why 5-axis setup changes the accuracy you receive
• 5
  Inspection evidence: what to request with the parts
• 6
  Lead time, MOQ and the real cost of waiting
• 7
  Certifications and materials that match your industry
• 8
  Common mistakes when comparing CNC suppliers
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  Step by step: verifying accuracy before you place the order

A tolerance number without a measuring method is half a claim. When a supplier states ±0.005 mm (±0.0002 in), the next question is which feature that covers and how it was checked. A bore, a slot and a 300 mm bolt circle do not behave the same way on the same machine.

Thermal drift matters on long cycles. A part that is measured straight off the table can read differently after it cools to room temperature. Suppliers who quote tight numbers usually let parts stabilize before final inspection, and they say so.

Material choice moves the achievable number too. Aluminium 6061 and 7075 cut cleanly and hold tight tolerances. Titanium TC4 (Ti-6Al-4V) and Inconel resist cutting, so tool deflection and heat become the limiting factors rather than the machine.

For most brackets, housings and manifolds, ±0.005 mm is more than the design needs. Chasing it across every dimension adds cost and inspection time without improving function. Pick the two or three features that matter and hold those tight.

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  Name the critical featuresTight tolerance belongs on fits and datums, not on every edge.
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  Ask for the instrumentCMM, micrometer or bore gauge, stated per feature.
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  Let parts stabilizeMeasure after cooldown to avoid a false out-of-tolerance reading.

On a 3-axis machine the tool moves in X, Y and Z only. Every new face needs a new fixture or a re-clamp. Each re-clamp adds a small position error, and those errors stack across five or six operations.

Simultaneous 5-axis adds rotary axes A and B. The tool reaches angled faces, undercuts and deep pockets in one setup. Fewer setups means fewer datum shifts, which is where most tolerance loss on complex parts actually comes from.

That advantage only shows up on the right parts. A flat plate with holes on one face does not need 5-axis time. Complex impellers, medical instruments, engine housings and thin-wall aerospace brackets are where the setup reduction pays for itself.

GreatLight runs 16 simultaneous 5-axis machining centers alongside 12 four-axis mills, 27 three-axis machines and 16 mill-turn centers. Maximum processing size is 4,000 mm, with travels such as 4,000 × 400 × 150 mm and 750 × 1,150 × 550 mm. A Ø400 mm rotary table covers round work.

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  Fewer setups, fewer errorsEach re-clamp adds position error that stacks.
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  Use it where it paysAngled faces, undercuts, deep pockets, thin walls.
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  Skip it on simple partsFlat plates with one-face holes run cheaper on 3-axis.

A supplier can hold good tolerances and still send you a batch with one bad part. The control that prevents this is inspection at three points: raw material check, in-process monitoring and final inspection before shipment.

Ask how the report is structured. A useful report lists the drawing dimension, the measured value and the instrument used. A single line that says "within tolerance" tells you nothing you can act on.

GreatLight inspects 100% of parts before shipment and provides reports on request. The qualification rate is 99.99%. If your program needs first article inspection or a certificate of conformance, say so at the quote stage so it is built into the routing.

Surface finish is part of accuracy on sealing faces and bearing seats. As-machined finish runs Ra 1.6–3.2 μm, high-finish work reaches Ra 0.8–1.6 μm, and fine finishing gets to Ra 0.2–0.8 μm. Specify finish by function, not by habit.

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  Three inspection pointsRaw material, in-process, final.
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  Dimension-value-instrumentA useful report shows all three in one row.
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  Finish by functionSealing faces and bearing seats need the tighter range.

Accuracy and schedule are linked. A shop that is overloaded rushes setups, and rushed setups are where dimensions drift. The practical check is whether the supplier gives you a quote window and a shipping window you can plan around.

GreatLight returns a quotation and a free DFM analysis within 12 hours. Production can start within 24 hours, and parts ship in 3–5 days. Historical late-delivery probability is below 2%.

MOQ is the other constraint. Programs that start at one prototype and grow to 10,000+ parts usually get stuck when a supplier demands a high minimum before the design is frozen. No minimum order quantity removes that friction.

The DFM step is worth reading carefully. Small changes, such as adding a corner radius or relaxing a non-critical tolerance, often cut cycle time without touching function. Review it before you approve the order.

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  Plan around two windowsQuote window and shipping window, both in writing.
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  Start smallOne prototype first, then scale to 10,000+ parts.
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  Read the DFM notesA radius change can cut cycle time for free.

Certificates are not decoration. They tell you which quality system the shop runs and which buyers it already serves. ISO 9001:2015 covers general quality management. IATF 16949:2016 applies to automotive and EV programs. ISO 13485:2016 is the medical device standard. ISO 27001:2022 covers information security, which matters when you send CAD files.

Material range is a second signal. A shop that stocks aluminium 6061, 6061-T6, 2024, 5052, 5083, 6063, 6082, 7075 and ADC12, plus stainless 303, 304, 316, 316L, 420, 430, 431, 440C and 17-4PH, is set up for mixed production rather than one niche.

Steel grades 1018, 1045, 4130, 4140, 4340, A36 and tool steel cover most structural work. Copper and brass run from C101 to C36000, with beryllium copper for spring contacts. Titanium TA1, TA2 and TC4, plus Inconel and magnesium AZ31B / AZ91D, handle the harder jobs.

Plastics matter more than buyers expect. ABS, PC, PMMA, POM, PA, PEEK, PP, HDPE and carbon fibre all behave differently under tool pressure. PEEK and carbon fibre are abrasive and need sharp tooling and slower feeds to hold tolerance.

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  Match the certificate to the sectorAutomotive, medical and general industrial use different standards.
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  Check the stock listA wide material range signals mixed production.
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  Plan for abrasivesPEEK and carbon fibre need sharp tooling and slower feeds.

The most common mistake is comparing one headline number. Two shops quoting ±0.005 mm may be measuring different features with different instruments. Put both quotes next to the same drawing feature before you decide.

The second mistake is ignoring the fixture plan. A part with six faces and no fixture discussion will lose accuracy at re-clamp. Ask how many setups the job needs and whether the critical features are cut in the same setup.

The third is treating finish as a cosmetic choice. On a hydraulic manifold, an O-ring groove, or a bearing bore, finish controls sealing and fit. Specify the Ra range with the dimension, not after the parts arrive.

Finally, confirm who sees your files. Uploads should be secure and confidential, and an NDA should be available on request. If a supplier hesitates on that, the accuracy conversation is secondary.

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  Compare the same featureOne headline number hides different measuring methods.
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  Ask for the setup countCritical features should be cut in one setup where possible.
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  Tie finish to functionSeals, bores and grooves need a stated Ra range.
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  Settle confidentiality firstNDA on request, secure uploads, no hesitation.