What files to send for a CNC quote

The short answer

Send a clean 3D model (STEP preferred), a dimensioned 2D PDF with datums and critical tolerances, plus a short note covering material, temper, finish, quantity, and need date. That package is what most CNC (and hybrid 3D-print→CNC) shops need to quote without a long email chain. Native CAD is optional insurance; screenshots and hand sketches alone are not enough for a firm machining quote.

When the pack is ready, upload it on the 3DWK quote page (quote-new.php). This guide is a practical buyer checklist—not a pricing sheet—and uses typical shop practice only.

Why the file pack matters more than the process buzzword

Quoters spend more time clarifying missing geometry, ambiguous finish callouts, and “ASAP” without a calendar date than they do debating 3-axis versus 5-axis. A complete RFQ package reduces clarification loops and lets the shop map setups, stock size, and inspection needs on the first pass. Incomplete packs stall even simple prismatic parts; complete packs help hybrid print→machine jobs move as fast as straight CNC.

If you already know which process you want, still send the same core files. Process choice follows geometry, material, and quantity—not the other way around. For process framing, see CNC vs 3D printing; for setup language, see the 3-axis vs 5-axis buyer guide. This article stays on what to attach.

The core package (checklist)

Use this as a pre-send gate before you hit upload:

Optional but useful: native CAD (SolidWorks, Inventor, Creo, etc.) for feature history; a short “intent” sentence (prototype fit check vs production sealing face); prior FAI or failed-fit photos when revisiting a known part.

STEP first: what “clean 3D” means

Export a solid STEP that matches the drawing revision. Typical buyer habits that save days:

• One solid body per part number (assemblies only when the quote is for a fitted set)
• Suppress cosmetic embosses that are not machined, or call them out as cast/print-only
• Remove construction surfaces, empty layers, and duplicate bodies
• Units stated (mm preferred for most industrial RFQs; if inches, say so in the note)
• Filename includes part number and revision, for example `BRACKET-104-RevC.step`

Shops can often open IGES, Parasolid, or native files, but STEP remains the safest default across CAM seats. If your CAD export has historically produced open surfaces, run a quick solid check before sending. Hybrid jobs (near-net print then machine) still need a STEP of the *finish* geometry plus a note on which faces are as-printed stock versus machined datums.

The 2D PDF is not optional for critical fits

A model alone does not carry inspection intent. The PDF should show:

• Datum scheme and GD&T where fits, alignment, or sealing matter (see GD&T basics for buyers)
• General tolerance block for non-critical dimensions
• Thread specifications (size, depth, class, helical insert if used)—see designing threads and tapped holes
• Edge breaks, chamfers, and deburr expectations where they affect assembly
• Surface roughness only where function needs it (Ra callouts guide)
• Material, temper, finish, and coating mask notes in the title block or a dedicated note balloon
• Revision letter matching the STEP filename

If you only have a model today, say so plainly: “3D only for budgetary quote; 2D with datums follows before release.” Budgetary and firm quotes are different commitments; do not expect a binding ship date from a model-only pack on tight-tolerance work.

Native CAD: when it helps

Native files help when feature trees, configurations, or sheet-metal flat patterns matter, or when the shop must edit stock allowances for a hybrid print→CNC path. They are not a substitute for STEP+PDF. Send native *in addition* when:

• Multiple configurations exist and only one is for this RFQ
• Sheet-metal bend tables or flat patterns drive blank size
• You expect collaborative DFM edits rather than a one-shot machine

Never send password-locked vault packages without an exchange method the shop already uses.

Material, finish, quantity, need date—write them once

Put these in the drawing note *and* the quote form so they survive a file rename:

• Material: for example 6061-T6, 304/316, 17-4PH condition, PA66, POM—avoid vague “aluminum” alone
• Finish: as-machined, bead blast, anodize type if known, passivate; mark cosmetic faces
• Quantity: piece count for this PO and a realistic next-buy band if you want break points discussed
• Need date: a calendar date or week; “ASAP” forces the shop to guess your real constraint
• Specials: heat treat, HIP for AM preforms, pressure test, FAI (first article inspection reports)

For cost and calendar context after the pack is complete, read CNC machining cost drivers and CNC machining lead time. Do not ask the shop to invent prices from a screenshot.

Hybrid 3D-print → CNC: extra files that prevent wrong quotes

When the path is additive near-net plus machining:

1. STEP of finished machined geometry

2. Note or second model showing print stock / oversize faces

3. Which datums are machined first

4. Powder or polymer system if already chosen (or “shop recommend”)

5. Whether the quote is for print-only, machine-only on customer preforms, or full hybrid

Without the stock-versus-finish split, shops often quote either a full billet CNC job or a print-only prototype—neither matching your intent. CNC vs 3D printing covers process choice; here the file difference is the oversize map.

RFQ tips that cut clarification loops

• One email or upload pack per part number (or a clear zip with a README of contents)
• Match revision letters across STEP, PDF, and the form field
• Call functional mates versus cosmetic faces in one short sentence
• List secondary ops you already know (inserts, hardware, assembly)
• Attach prior quote IDs or PO numbers when this is a revise-and-resubmit
• If ITAR/export or NDA applies, say so before uploading proprietary models to any portal

Upload the pack on quote-new.php. If something is still in flux, freeze datums and critical fits first; changing those after CAM starts is what burns lead time.

Common mistakes

• Sending STL alone for a precision CNC quote (mesh is fine for form/fit print checks, weak for toleranced machining)
• PDF without revision while STEP is Rev C
• “Same as last time” with no part number or date
• Critical threads only in the model name, not on the drawing
• Finish called out as “nice” with no mask or cosmetic face map
• Assembly STEP with no indication which body is this RFQ

Illustration 1 shows a typical file pack flow from CAD export to quote. Illustration 2 is a buyer readiness checklist you can run in five minutes before upload.

What “good enough for a firm quote” looks like

A firm machining quote usually needs enough definition for stock, setups, tooling risk, and inspection. That means solid STEP + PDF with datums on fits + material/finish/qty/date. A budgetary range can sometimes start from STEP + material + qty alone, with clear labeling that numbers are not release-ready. Say which kind you want in the RFQ note so the shop does not over-promise calendar dates.

For reading how preliminary online ranges relate to a later firm quote, see reading preliminary online quote (min / mid / max). File completeness is what moves you from range to release.

What to do next

1. Export STEP and PDF at the same revision.

2. Fill material, temper, finish, qty, and need date on the drawing and the form.

3. Add hybrid oversize notes only if print→machine applies.

4. Upload via quote-new.php.

Related reading on 3DWK: CNC machining service, designing threads, GD&T basics, surface roughness Ra, edge break/chamfer callouts, CNC pockets and thin walls, and first article inspection reports. Send the pack once, complete—then iterate on DFM comments instead of missing files.

Common questions