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How to vet a machine shop before you place the first order

August 7, 2026

A shop that cannot make your part rarely says so. It quotes, wins, and everyone finds out at first article. The way to avoid that is not a longer contract. It is a short set of questions with answers that can be checked.

The machine list, read properly

Ask for a machine list with model, quantity, year and control. Then read it for three things:

1. Envelope. Does anything on the list have a table large enough for your part with fixturing around it? A 600 mm part on a machine with a 700 mm table is tight.
2. Type mix. A shop with eight 3-axis mills and no lathe will subcontract your turned features, which is fine if they say so and a problem if they do not.
3. Age and control. Older machines in good hands make excellent parts. What matters more is whether the control matches the programming the shop does, and whether there is more than one machine that can run your job if one goes down.

“We have twenty machines” is not an answer. “We have six Haas VF-2, two Doosan Lynx 220 with live tooling, one 5-axis and a wire EDM” is.

Inspection is the real capability question

Machining capability is easy to buy. Measurement capability is what separates shops.

• What do you measure with? Calipers and micrometers, height gauge, profile projector, CMM. A CMM changes what a shop can prove.
• Who measures, and when? First article, in process, final. A shop where the operator is also the only inspector has a structural problem on tight work.
• Are the instruments calibrated, and can I see the certificates? This is a simple yes or no and the answer is revealing.
• Can you send me a sample report? Ask for a redacted dimensional report from another job. The format and the completeness tell you a lot in thirty seconds.

If your part has a CMM-level tolerance and the shop measures with hand tools, you have learned something important without an audit.

Ask about a part they already make

Not a customer name, which they should not give you, but a part like yours: similar size, similar material, similar tightest tolerance. Then ask what was difficult about it and what they changed.

A shop that answers with a specific feature and a specific fix has made the part. A shop that says it was no problem is either lucky or has not made anything like it.

The first article conversation

Agree three things before the purchase order:

• What a first article means here. How many pieces, measured against what, reported how
• Who signs it off and how long that takes. Your approval time sits inside the lead time
• What happens if it fails. Rework, replacement, credit, and who pays freight both ways

Putting this in writing before production costs one email. Settling it after a failed inspection costs a schedule.

Paperwork that has to exist

• Business registration and the ability to invoice you as an exporter, or a stated trading partner that does it for them
• Bank details in the company name. A request to pay a personal account is a stop signal
• Material traceability, if you need it. Ask whether they can supply mill certificates and what the lead time penalty is
• Who prepares the export documents. Many capable shops are domestic only, which is workable but has to be known in advance

Small tests before a big order

Pay for a sample. A paid first article tells you more than any audit, and a shop that treats a paid sample seriously is showing you how it will treat the order.

Split the first production order. Half now, half after inspection. Shops accept this more often than buyers expect.

Run a video call during production hours. Ask to see the machines running, the inspection room and the packing area. Empty machines at eleven in the morning, or a spotless floor with no chips anywhere, both deserve a follow up question.

Red flags worth acting on

• A quote that arrives in twenty minutes on a tight tolerance part, with no questions
• A price that drops sharply when you push, without anything changing in the scope
• No questions about your datums or your critical features
• Reluctance to name what is subcontracted
• Photos of a facility that do not match the machine list

What we check before a shop joins our list

We ask for the machine list, the largest envelope, the materials cut weekly, the inspection equipment and export experience, then we compare that against the requests we hold. We do not publish shop names and we do not take a shop onto the list because it paid to be there. The full version of what we ask is on the become a partner page.

A question set you can send as an email

Copy this into a message and send it to any shop before a first order. The answers take a shop ten minutes and tell you more than a brochure.

1. Machine list with model, quantity and year, and the largest part envelope you can hold.
2. Which processes are done in house and which are subcontracted, by name of process.
3. Inspection equipment on site, and whether calibration certificates are available.
4. A redacted dimensional report from a recent job, as an example of your format.
5. A part you already make with a similar size, material and tolerance, and what was difficult about it.
6. Typical lead time for a first order of 250 pieces in aluminium, from purchase order.
7. Payment terms for a first order, and the bank account name.
8. Who prepares export documents, and whether you have shipped to my region before.

A shop that answers all eight clearly is worth a sample order. A shop that answers three of them with marketing copy has told you what working with it will be like.

Scoring the answers

Weight them by what your part needs. On a tight tolerance part, the inspection answers matter most. On a large part, the envelope and the fixturing answer matter most. On a first import, the export and payment answers matter most. A shop does not have to be strong at everything, it has to be strong where your risk actually sits.

If you would rather not run this process yourself on a first order, send the drawing and we will do the shortlisting part. The guide on comparing the quotes that come back covers what to do with the answers.

Questions we get on this

Keep reading

• CMM, height gauge or optical comparator: choosing the check for each feature
• Tolerances on a machined part, explained for the person buying it