CNC quote turnaround — what to expect (and when to worry).

Instant-quote systems (Protolabs, Hubs, Xometry) use software to:

1. Read uploaded STEP file
2. Calculate bounding box, volume, surface area
3. Estimate material cost from volume + material type
4. Estimate machining time from geometric complexity (feature count, surface-to-volume ratio)
5. Apply business rules (minimum prices, standard finishes, standard tolerances)
6. Add markup for margin

What they can't evaluate:

• Whether the drawing tolerances are actually achievable with standard methods
• Whether the geometry has manufacturing issues (tall thin walls, inaccessible features)
• Whether the specified material is appropriate for the application
• Whether there's a cheaper way to make the same functional part

For simple prototype parts in standard materials, instant quotes are adequate and convenient. For anything more complex, the instant price is often inflated (software plays safe) or misleading (doesn't catch manufacturability problems).

Quotes that take 1-2 days from a real engineer typically include:

• Material confirmation — specified grade available, stock size optimized for your part
• Tolerance review — which features drive cost, suggestions for relaxation
• Feature review — any geometry concerns (undercuts, thin walls, access)
• Process recommendation — whether 3-axis, 3+2, Swiss, or 5-axis is optimal
• Quantity break pricing — multiple quantity scenarios
• Lead time options — standard, expedited, what each costs
• Finish and inspection specifics — what's included in the price
• Alternative material suggestion if applicable

For production parts, the difference between an instant quote and an engineered quote is typically 10-30% in actual landed cost, and significantly better reliability (no surprises on first parts).

• No breakdown by line item: quote is just "part: $50". Means no transparency about what you're paying for.
• No lead time stated: suppliers who won't commit to a lead time often have capacity or supply chain issues.
• Same unit price at quantities 1, 10, and 100: either the supplier has no real scale or they're inflating prototype pricing. Ask why.
• Material "equivalent" without explicit grade: "aluminum 6000-series equivalent" instead of "6061-T6" suggests they may substitute. Verify specifically what material ships.
• Quote references a different drawing revision: attention to detail issue. Get the correct revision quoted before proceeding.
• Absence of any DFM comments from an engineer quote: either the drawing is perfect (rare) or they didn't actually review it. Probe with "did you see any cost drivers in the drawing?"