Get Something CNC Machined: Four Routes Compared

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  The four real answers when you get something CNC machined
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  Local job shops: fast talk, limited travel
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  Online marketplaces: instant price, hidden process
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  Contract factories: the process chain is the product
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  Machining it yourself: control you pay for in hours
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  What to send and what to ask before you commit
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  Which route fits your part

There are only four places a part actually gets cut: a local machine shop, an online marketplace that brokers the job out, a contract manufacturing factory, or a machine you own. Everything else is a variation on those. The question of where to get something cnc machined is really a question about which of these four fits your part, your volume, and how much of your design you are willing to hand over.

Each route has a different failure mode. Local shops fail on capacity. Marketplaces fail on traceability. Factories fail on minimum order quantity. Owning a machine fails on your time. Knowing which failure you can live with narrows the choice fast.

The rest of this page walks through how each route actually processes your part, what tolerance and material limits show up in practice, and the point where you should switch from one route to another.

A local shop is usually a 3-axis or 4-axis mill with a manual lathe in the corner. You talk to the person who runs the machine. That is worth a lot when a drawing is ambiguous. Setup happens the same week, and you can drive over and look at the first part before the rest of the run is cut.

The limit is machine travel and axis count. Most local shops cannot cut a part that needs five sides in one setup, so they refixture two or three times. Every refixture adds stack-up error. If your print calls for ±0.005 mm across a bore pattern on three faces, a shop that refixtures will struggle to hold it and will tell you so.

Material is the second limit. A small shop stocks 6061 and 303 stainless. Ask for Inconel, 17-4PH, or PEEK and they order it, which adds days and often a minimum purchase of a full bar. You pay for the leftover bar.

Local shops fit one-off fixtures, weldments, repair parts, and brackets where the tolerance is loose and the schedule is short. They are a poor fit for a 10,000-piece run or a part with an organic surface that needs simultaneous 5-axis motion.

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  Good fitOne to fifty parts, loose tolerance, drawing questions you want answered in person
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  Poor fitMulti-face tight tolerances, exotic alloys, runs above a few hundred pieces
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  Watch forRefixturing on the quote. Ask how many setups.

Marketplaces take your STEP file and return a price in minutes. Behind that price is a queue of partner shops you never see. The platform picks one based on load and margin. For a simple bracket in 6061 that is genuinely convenient, and the price is often lower than a local shop because the work goes to whoever is cheapest that week.

The process is invisible. You do not know the machine, the fixture, or who inspected the part. If the part is out of tolerance, you ship it back and hope the second attempt is better. There is no engineer to call and ask why the bore came in oval.

IP is the real cost. Your CAD file moves through a broker and at least one subcontractor. If the part is a patent-pending mechanism or a medical device, that path is hard to defend in an audit. A marketplace is fine for a fixture or a housing. It is a weak choice for a competitive product you have not launched.

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  Good fitSimple geometry, cost comparison, one-off prototypes, no sensitive IP
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  Poor fitTight tolerances, regulated industries, parts you cannot show a broker
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  Watch forWho actually cuts the part and who signs the inspection report

A contract factory owns the machines, the metrology, and the finishing line. GreatLight runs 127 high-precision CNC machines across three plants in Dongguan and Singapore, including 16 simultaneous 5-axis machining centers and 16 mill-turn centers. Maximum processing size is 4,000 mm, with a Ø400 mm rotary table for parts that need rotation in the cut.

The reason to use a factory is not just axis count. It is that one supplier holds the whole chain. A part that needs machining, anodizing, laser marking, and a final CMM report does not travel between three vendors with three sets of handling marks. It stays on one route with one inspection record.

Tolerance is where this route separates from the other two. GreatLight holds ±0.005 mm (±0.0002 in) and finishes down to Ra 0.2–0.8 μm when the drawing asks for it. That number only means something with inspection behind it. Every shipment gets 100% inspection, and raw material, in-process, and final checks are recorded and available on request.

Certifications matter for regulated buyers. ISO 9001:2015, IATF 16949:2016, ISO 13485:2016, and ISO 27001:2022 cover quality, automotive, medical, and information security. If your part goes into a car or a patient-contact device, those certificates are the entry ticket, not a bonus.

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  Good fitComplex geometry, regulated markets, finishing plus machining under one PO
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  Poor fitA single loose-tolerance part where the quote paperwork costs more than the part
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  Watch forWhether finishing and inspection are in-house or subcontracted

A benchtop mill and a CAM seat will cut a real part. For a hobby bracket or a quick fixture, that is often the fastest route because there is no quoting, no shipping, and no NDA. You iterate the same afternoon.

The math changes when the part needs to be right. A hobby-class machine rarely holds ±0.005 mm over a long cut, and thermal drift shows up on aluminum after an hour of roughing. You also become the inspector, and you need a micrometer and a granite plate to know whether the part is good.

The honest boundary is this: machine it yourself when the part is a means, not a product. Once the part is something a customer pays for, the cost of a scrapped run and a missed date usually beats the savings from cutting it in-house.

Any of the four routes can quote from a STEP file and a PDF drawing. The drawing is what decides the price. A print with a tight tolerance on a non-functional face drives cost up for no reason. Call out only the dimensions that matter and let the rest run to general tolerance.

Ask three questions before you place the order. How many setups does the part need? What machine will run it? Who inspects it, and with what? The answers tell you more than the price. A shop that cannot answer the setup question has not looked at the part.

Send material, quantity, finish, and any certification requirement in the first message. A quote that assumes 6061 when you need 7075 is not a real quote. At GreatLight, quotation and free DFM analysis come back within 12 hours, and production can start within 24 hours after approval.

Keep the NDA question early if the design is sensitive. GreatLight treats uploads as secure and confidential and signs an NDA on request, which is standard practice for a factory and rare with a broker.