How to Source CNC Machined Parts from U.S. Shops
A practical checklist for engineers sending an RFQ to American machine shops: drawings, tolerances, materials, quantities, what drives lead time, and how Vendra gets it done faster.
Most quoting delays have nothing to do with the shop. They come from RFQs that leave questions open: which revision, which temper, which features actually need to hold a tight tolerance. Every open question costs a round of email, and every round costs days.
The fix is to send an RFQ that answers the shop's questions before they ask them, and to send it to the right shop the first time. This guide covers both, and how teams like Reflect Orbital use Vendra to skip the back-and-forth entirely.
Start with a complete drawing package
A shop quotes what it can read. Send both files, every time:
- A STEP file for the geometry
- A PDF drawing for everything the model can't carry: tolerances, GD&T, surface finish, thread callouts, and notes
The drawing is the contract. If the model and the drawing disagree, most shops will build to the drawing, so make sure both carry the same revision letter.
On the drawing itself:
- Call out material and temper, for example 6061-T6, not just "aluminum"
- Specify threads fully, for example 1/4-20 UNC-2B, and note any helicoil or insert
- Spell out the finish, for example anodize per MIL-A-8625 Type II, Class 2, black, or Type III hardcoat where wear matters
On Vendra, you upload the package once and specify every requirement in one place, instead of re-explaining it to each shop you email.
Put tight tolerances only where they matter
Tolerances are the biggest lever on price that engineers control. Use a sensible general tolerance in the title block, then call out the few features that truly need more.
| Tolerance | What it usually means for the shop |
|---|---|
| ±0.005 in. (±0.13 mm) | Standard for most CNC work. No premium. |
| ±0.001 in. (±0.025 mm) | Achievable, but slower and more inspection. Often a CMM report. |
| Tighter than ±0.0005 in. | Specialty work: grinding, temperature control, and fewer capable shops. |
Tight-tolerance work is where shop fit matters most. Vendra matches each part to U.S. shops with the machines and inspection capability to hold it, so you aren't paying a generalist to learn on your part.
Ask for inspection and paperwork up front
If you need it at delivery, put it in the RFQ so it gets quoted:
- Material certs that trace the stock back to the mill
- First article inspection to AS9102 for flight or production hardware
- Certificate of conformance with the shipment
- ITAR status. If the part or drawing is export controlled, say so up front so it only goes to shops registered with the Directorate of Defense Trade Controls. Vendra is ITAR registered, so controlled work stays with registered U.S. shops.
Choose the material for the job
Material drives machining time, tooling, and lead time. Common choices:
| Material | Machinability | Typical use |
|---|---|---|
| 6061-T6 aluminum | Excellent | Brackets, housings, fixtures |
| 7075-T6 aluminum | Good | High-strength aerospace structures |
| 17-4 PH stainless | Fair | Corrosion-resistant load-bearing parts |
| Ti-6Al-4V | Difficult | Flight hardware, medical implants |
6061 is on every shop's shelf. Titanium and specialty alloys often have to be ordered in, which can add more lead time than the machining does. Vendra routes those parts to shops with experience in the alloy, so material and know-how aren't the bottleneck.
Quote more than one quantity
Setup is a fixed cost, so the per-part price falls as quantity rises. Ask for two or three quantity breaks, for example 10, 50, and 250. You'll see the price curve in one round, and you won't have to re-quote when the program grows.
Know what drives lead time
- Material availability. Stock alloys ship today; exotics can take weeks.
- Setups and operations. Every extra fixture or 5-axis operation adds time.
- Secondary processes. Anodize, plating, heat treat, and passivation usually happen at outside processors, and each handoff adds days.
- Inspection. CMM reports and first articles are time well spent, but they are time.
- Shop capacity. The right shop with an open machine beats a perfect shop with a six-week backlog.
Secondary processes are where most schedules slip, and where Vendra helps most. One order covers machining, coating, and post-processing, and Vendra manages every handoff between them.
"Vendra is really good at doing multi-step manufacturing processes. If we just need a part CNC machined, we have the ability to do it in-house. Where Vendra really helps is when we need that part coated, masked or post-processed."
Ronald Trang, Mechanical Engineer, Reflect Orbital
Your RFQ checklist
- STEP file and PDF drawing, at the same revision
- Material and temper
- Two or three quantity breaks
- Finish and every secondary process
- Critical tolerances and inspection requirements
- Certs needed at delivery, and ITAR status
- Need-by date and ship-to location
Why engineering teams source with Vendra
You can work through that checklist shop by shop, or send it once to Vendra.
- The right shop, not every shop. Vendra matches each part to vetted U.S. shops with the right machines, material experience, and certifications, instead of blasting your RFQ to everyone.
- Fast quotes. Quotes come back in under 24 hours. Reflect Orbital gets its first quote in under five hours on average.
- Multi-step parts, one order. Machining, finishing, coating, and inspection are coordinated end to end, so you don't manage a separate supplier for every step.
- Built for aerospace and defense. Vendra is ITAR registered, AS9100D and ISO 9001:2015 certified, and NIST 800-171 compliant for CUI.
- A direct line to the shop. You can see who is making your part and talk to them when requirements get specific, with Vendra managing the job from RFQ to delivery.
Teams building satellites and spacecraft already work this way. Read how Reflect Orbital and AstroForge get complex parts made with Vendra.
Ready to send your next part? Request a quote and get matched with the right U.S. shop today.