"How much will this cost?" doesn't have a single answer until five variables are fixed. Understanding them is the difference between a quote that surprises you and one you could have roughly predicted yourself.
Material
Raw material cost is the most obvious driver, but it's not just price per kilogram — it's also machinability. Steel and aluminum machine quickly and predictably; stainless steel work-hardens and cuts slower, which shows up as more machine time for the same geometry. Aluminum carries a further premium for shops sourcing it internationally rather than domestically.
Machine time
This is usually the largest line item. It's a function of part geometry (how much material has to be removed, how many setups and tool changes are needed) and the machine's cutting parameters for that material. A part that needs to be flipped and re-fixtured mid-program costs more than one machinable in a single setup — not because the material or tolerance changed, but because machine time and labor did.
Tolerance
Standard CNC tolerances (roughly IT7–IT9, or ±0.02–0.05 mm) are achievable at normal cutting speeds. Tighter tolerances mean slower cuts, more in-process measurement, and sometimes a dedicated finishing pass — all of which add machine time without changing the raw material used. The cost jump from "normal" to "tight" tolerance is rarely proportional to how much tighter the number looks on paper.
Series size
Programming, tool setup, and first-article inspection are fixed costs regardless of whether you order 1 part or 1,000. Spread across a larger series, that fixed cost per unit drops — which is why a quote for 10 units and a quote for 500 units of the same part rarely scale linearly.
Finish
Any secondary finishing — powder coating, anodizing, plating — is priced on top of the machined part, and its cost usually depends more on surface area and batch logistics than on the machining itself.
Where the real savings are
Of these five, the one most within the buyer's control is tolerance: reviewing a drawing to confirm which dimensions are genuinely functional (versus copied from a default template) is usually the single highest-leverage way to bring a quote down, because it directly reduces machine time without touching material or series size.
A rough mental model
| Driver | What changes it | How much it typically matters |
|---|---|---|
| Material | Type, machinability, sourcing | Moderate |
| Machine time | Geometry, setups, tool changes | High |
| Tolerance | How tight, on how many dimensions | High |
| Series size | Fixed cost spread over more units | High at low volumes |
| Finish | Surface area, process | Low to moderate |
We quote CNC turning and milling within 24–48 hours, with tolerance and material called out explicitly so you can see what's driving the number. See our CNC turning and CNC milling pages, or request a quote with your drawing.