Guides / Choosing a Supplier

Picking a Brass Machining Shop Before You Send the Drawing

September 21, 2026

Most machine shops can cut brass. Far fewer can hand you a burr free, correctly gauged, consistently finished brass fitting at the price they quoted. The difference is not skill, it is whether this is normal work for them.

Here is how to tell before you commit.

1. What machine would you run this on, and why?

The highest value question, and the answer arrives in seconds if the shop knows.

Good answer: “That is a Swiss part. Twenty six millimetre bar, live tooling for the cross hole and the hex, sub spindle for the back face. It comes off complete.”

Answer that should worry you: a general statement about capability without naming a route.

Machine choice is the largest avoidable cost in brass work, and a shop that cannot describe the route has not thought about your part yet. See Swiss turning brass parts.

2. Which brass grades do you run every week?

Not “can you run”. Do you run.

C360 and C385 should be immediate. If your part is lead-free, the follow up matters more: have you machined C69300 silicon brass or a bismuth brass in production, and can you supply the mill certificate?

Nearly every shop says they can run lead-free brass. Considerably fewer have shipped it. Silicon brass work hardens and threads differently, and the learning happens on somebody’s parts. See leaded and lead-free brass compared.

3. What is your bar capacity, and do you have bar feeders?

A shop feeding twelve foot bars and running unattended overnight has a completely different cost structure from one loading blanks by hand.

Ask the diameter range too. If your part needs 38 mm bar and their largest Swiss takes 32 mm, you want to know now.

4. How do you handle burrs inside bores?

The question that separates shops that have shipped fittings from shops that have not.

Good answer names a method: a deburring tool with a programmed path, brush deburring, abrasive flow, thermal deburring, or a design suggestion to break the cross hole into a chamfer.

Answer that should worry you: “We deburr all parts.” That describes external edges. The burr that fails your leak test is inside the bore where nobody can see it. See the burr inside the bore nobody can see.

A shop that raises this unprompted when you describe your part has almost certainly been bitten by it before, which is exactly the experience you want.

5. How do you check sealing threads?

The answer should include the word gauge.

Go and no-go ring or plug gauges to the relevant standard, checked at a stated frequency, not a visual check and not a thread micrometer. On tapered threads a part that is out is scrap rather than rework, so the check has to be in process. See thread standards on brass fittings.

6. What finishing do you do in house?

Tumbling in house is common and useful. Polishing in house is less common. Plating in house is rare.

This is a lead time question more than a price question. Parts that leave for plating and come back add weeks of calendar time regardless of how fast the plating itself is. Ask before you build a schedule around a quote. See surface finishes and plating for brass.

7. What certificates can you supply, and how is traceability maintained?

Two halves, and the second one is the real question.

Any shop can pass on a mill certificate. What makes it meaningful is the internal trail linking a bar batch to your part lot numbers. A shop with a system answers straight away. A shop without one talks about the certificate instead. See material certificates for brass parts.

If your part is regulated, ask the specific question rather than the general one. A shop cannot certify your product to NSF/ANSI 61, and one that claims it can has misunderstood something. See NSF/ANSI 61 and 372 for brass fittings.

8. What is your quote turnaround, and what do you need from me?

A shop that asks good questions back is a good sign. A shop that quotes a threaded pressure fitting without asking about thread class, internal burrs or finish has probably not read the drawing.

Questions you should welcome: which threads seal, what is the internal burr requirement, does the finish apply before or after plating, is the annual quantity real.

9. Will you tell me when my part does not suit you?

The answer you want is a specific example of when they said no.

A shop that takes everything is a shop that will learn on your job at some point. A shop that says “we would decline that, it belongs on a bigger machine, try someone with a 50 mm bar capacity” has just given you more value than a quote would have.

The red flags, gathered

• Cannot name the machine they would use
• Says yes to every grade and every quantity without qualification
• Has no answer for burrs inside bores beyond “we deburr”
• Claims they can certify your part to a product standard
• Quotes a complex fitting without asking a single question
• Quote is far below the others and nobody can explain why

And the practical shortcut

Sending the same drawing to fifteen shops to find the three that fit is a week of your time, and most of those shops will quote a part that does not suit them rather than decline it.

That is the whole reason this site exists. We read the part, match it to shops that actually run this kind of work and let them quote you directly. You deal with them, not with us, and there is no commission on the order.

Before you send anything, it is worth running through the brass RFQ checklist so the quotes you get back are comparable.

Send your drawing and we will reply within 24 business hours with matched shops, or tell you plainly if we cannot find a good fit.

Frequently asked questions

Keep reading

• The Twelve Things a Brass Quote Needs From Your Drawing
• When Buying Machining Leads Pays, and When It Does Not