CNC machining drawing package checklist for a complete RFQ

This how-to is for a US or EU engineer or buyer building an RFQ for a Dongguan CNC factory. You already have a model. The shop still cannot price toolpaths, fixtures, or inspection from a STEP alone.

A complete package lets custom CNC machining services quote the part you intend to inspect, not a best-guess solid.

Key takeaways

• STEP carries shape. The PDF carries law: datums, tolerances, threads, finish, and revision.
• One revision letter on the title block, the STEP filename, and the email subject. Mixed revisions kill quotes.
• Material must include temper (6061-T6, not “aluminum”). Finish must include type and whether sizes are before or after coat.
• Unmarked sizes can sit on ISO 2768-1 (1989). Fits cannot. Write the numbers and the gauge when the band is tight.
• Hardware, inserts, masking, and FAI scope belong in the zip or the notes. They do not belong in a chat three days after the quote.

What belongs in a CNC machining drawing package checklist

A CNC machining drawing package checklist starts with two files that agree: a 3D body and a 2D drawing that owns dimensions.

Use STEP AP214 or AP242 as the default solid. IGES and X_T are acceptable if your CAD exports them cleanly. STL is a visual check, not a machining file. Mesh files hide fillets as facets and lose thread pitch. The PDF must show datums, GD&T or plus/minus fits, thread callouts, surface texture, a revision block, and a notes list. If the PDF is a shaded screenshot of the model, it is not a drawing.

ASME Y14.5-2018 is the usual language for those datums. If you use a general class instead of a full GD&T scheme, name it: ISO 2768-m or ISO 2768-f per ISO 2768-1 (1989). Do not leave the title block blank. Medium class on 6-30 mm is ±0.2 mm. Fine class on the same range is ±0.1 mm. Neither is a press fit.

Add, as files or notes: material and temper, quantity (including a prototype break), finish, inspection scope, and hardware (helicoils, pins, masks). Photos of a sample help when you are matching an existing part. They do not replace the PDF. A mill certificate request (for example EN 10204 3.1) belongs on the RFQ if incoming QA will block the lot without it.

Native SolidWorks, Creo, or NX files can ride along for the shop that can open them. They are extras. The receiving PC may not have your CAD license, your toolbox holes, or your suppressed configurations. STEP is the common language. If configurations exist (left/right, with/without inserts), export only the body you want cut, or send two clearly named STEPs.

Assemble the RFQ files in this order

Work through the package as a procedure, not as a folder dump.

1. Export a STEP (AP214 or AP242) from the released CAD configuration. Done when every body you want machined is in the file, suppressed configs are gone, and a second person can open it without missing holes.
2. Create a PDF drawing with datums, tolerances, threads, and a revision letter that matches the STEP filename. Done when a programmer can pick a primary datum without emailing you, and every fit exists as a real face in the STEP.
3. Fill the title-block notes: material + temper, quantity, finish, Ra (use Ra 3.2 if you have no cosmetic spec), and inspection. Done when a buyer can quote without a second email for “what alloy.”
4. Add process notes for coating, masking, and which dimensions apply before finish. Done when Type II 5-25 µm per MIL-A-8625F (1993) cannot silently steal a fit.
5. Zip the STEP, PDF, and a one-line file list (revision, date, part number). Done when filenames match the title block exactly, including the same Rev letter.
6. Write the email or form header: part number, qty breaks, ship-to country, and whether the drawing or the model governs. Done when the zip and the header tell one story.

The common failure is sending only a STEP, or a PDF that says “dimensions from model” with no datums. The shop will quote a shape. It will not quote your fits. “See CAD” on a blank title block is how two estimators pick two different hole sizes.

If you are still in prototype quantity, the same package applies. Small-batch CNC machining still needs a revision-controlled PDF. Five pieces with no datums still get a guessed fixture. Fifty pieces with mixed Rev B and Rev C files get a guessed hole pattern.

For milled plates, the PDF should at least show the primary face, hole pattern, and pocket depths. For turned parts, show datums on the diameters you will inspect, not only a pretty isometric. CNC milling and CNC turning both start from the same rule: the 2D sheet owns the sizes you will reject.

Notes that change quote risk

Notes change tools, fixtures, and inspection time. A missing note is not “the shop will ask.” It is “the shop will assume the cheap path.”

Material: “6061-T6 plate” is quotable. “Aluminum” is not. 6061-T6, 7075-T6, and 6082-T6 do not cut, anodize, or yield the same. Finish: “Type II anodize, black, 8-12 µm, dimensions before coat, mask 4× M4” is quotable. “Anodize” is not. Threads: call ISO metric or UNC, class, and depth. M6×1-6H, 12 mm hole, 10 mm thread, incomplete threads allowed 2 mm from the floor, is a tap program. “M6” is a guess at depth and whether a helical insert follows.

Inserts: call helical insert after tap and which holes. Pins: call press-fit diameter and whether the shop installs them. Masking: call which faces stay conductive. Laser mark: call content, height, and depth or etch. If the mark sits on an anodized face, say whether it is after dye.

Inspection: “FAI with ballooned PDF, CMM on datums A-B-C and the two press fits” is quotable. “Good quality” is not. If you need a mill certificate, say so on the RFQ, not after the PO. If you will reject on true position 0.05 mm, that CMM program belongs in the hour estimate.

For coatings, MIL-A-8625F (1993) Type II vs Type III is a thickness and wear choice. Type II is commonly 5-25 µm. Type III is a hardcoat with a different build and wear story. Put the type, color, thickness range, and before/after size rule on the drawing. Bead blast before anodize changes cosmetics and can move a 5 µm band. If blast is only for appearance, keep it off the fit bores.

Ra 3.2 µm is a normal as-milled default. Ra 0.8 µm on every face is extra finish passes. Call Ra 0.8 only on seal faces or bearing seats. A cosmetic “make it pretty” note without a Ra or blast spec is not inspectable.

How to use this CNC machining drawing package checklist before you hit send

How to use this CNC machining drawing package checklist is a 10-minute self-audit against the zip you are about to email.

Open the STEP and confirm the PDF revision letter is in the filename. Confirm every fit on the PDF exists as a real face or hole in the STEP. Confirm unmarked sizes have a general class. Confirm quantity and ship-to country are in the email body. Confirm the notes list names temper, finish, and inspection in words a stranger can parse.

Walk this audit list. You send when every line is yes. You stop when any line is no.

1. Filenames: Pxxxxx_REV_C.step and Pxxxxx_REV_C.pdf match the title-block rev.
2. Only one PDF is in the zip. Old Rev B is deleted, not sitting next to Rev C.
3. Datums A, B, and C (or an explicit single-plane scheme) are on the PDF.
4. General tolerance is named (ISO 2768-m or equivalent). Fits have numbers.
5. Material is grade plus temper. Product form (plate/bar) is named if grain matters.
6. Finish is type, color or class, thickness if coated, before/after size, mask list.
7. Threads have standard, class, hole depth, and thread depth.
8. Inspection names FAI vs sampling and which features use CMM or gauges.
9. Quantity breaks and ship-to country are in the header, not only in a chat.
10. Model vs drawing precedence is written. Hardware and inserts are listed or marked “none.”

If two PDFs exist (old Rev B and new Rev C), delete the old one from the zip. Factories will quote the first file that opens. Native SolidWorks or Creo can ride along. They are not a substitute.

This is also the moment to send the package to YXT CNC contact if you want a DFM pass before you lock the revision. Ask about missing datums, impossible mill radii, and coating vs size. A 0.2 mm internal corner in a 25 mm pocket is a 0.4 mm mill with a long stick-out. Catch that in the package, not after the PO.

Worked RFQ: one zip for a 6061 cover

Copy this package for a typical prismatic part. Part P-22108, 6061-T6 plate cover, 150 × 90 × 12 mm, aluminum CNC stock assumed as plate.

Files:

• P-22108_REV_C.step (AP242, one solid, no leftover construction bodies)
• P-22108_REV_C.pdf (A3, datums A-B-C, ISO 2768-m, revision C dated on the block)
• P-22108_REV_C_filelist.txt (one line: STEP + PDF, Rev C, 2026-03-12)

PDF notes that make the quote stable:

• Material: 6061-T6 plate, mill cert if required (write “EN 10204 3.1 required” only if you will check it).
• Finish: Type II black, 8-12 µm, dimensions before coat, mask 2× Ø8 H7 bores and datum A pads.
• Threads: 6× M4×0.7-6H, 10 mm hole, 8 mm thread.
• Inspection: ballooned FAI, CMM on A-B-C and the two Ø8 bores, later lots sample those bores.
• Quantity: 10 / 50 / 200. First article ships with the FAI packet.
• Precedence: drawing governs sizes and notes; STEP governs unspecified radii ≥ 0.5 mm as modeled.

Email header the buyer can paste:

RFQ P-22108 Rev C | 6061-T6 | Type II black 8-12 µm before coat | qty 10/50/200 | FAI + CMM on datums and Ø8 | ship-to Germany

That is a complete drawing package plus the commercial line the estimator needs. The incomplete version of the same job is a STEP named cover_final2.stp, a PDF still titled Rev A, material “AL,” and “anodize.” The shop will still answer. The answer will move after someone asks which hole is H7 and whether sizes are before dye.

Item	Required?	Why it changes the quote	Watch-out
STEP AP214/AP242	Yes	Toolpaths and volume	Suppress leftover bodies
PDF with datums + rev	Yes	Fits, threads, inspection	Must match STEP rev
Material + temper	Yes	Feeds, distortion, certs	“Aluminum” is not a grade
Finish + before/after size	If coated	Cycle time and masking	Type II 5-25 µm can eat a fit
Quantity + breaks	Yes	Setup amortization	Prototype vs 200 pcs differs
Inspection scope	Yes	CMM time	FAI vs 100% is not the same
Native CAD only	No	Receiver may not open it	Send STEP anyway
File list / rev letter	Yes	Stops mixed-rev zips	One letter in three places
Inserts / hardware list	If used	Extra tap and install ops	Helicoil after tap is a note
Model vs drawing rule	Yes	Conflict resolution	Do not leave “see CAD”

Bottom line: if the zip contains STEP + PDF + temper + finish + quantity + inspection, you have a complete RFQ package. Anything less is a conversation, not a quote basis.

Name files so a stranger can sort them. Put part number and revision in the email subject. Many shops assume the model governs shape. Pick one rule and put it on the PDF. If a fillet is in the STEP and sharp on the PDF, the programmer will pick one, and it may not be the one you meant.

FAQ

Is a STEP file enough for a CNC quote from China?

No. A STEP gives shape. A PDF with datums, revision, material, finish, and inspection is what makes the quote match the part. Toolpaths can be written from a solid. Fits, thread depth, and coating cannot. A STEP-only RFQ usually comes back with “confirm tolerances” or with ISO 2768-m applied to faces you thought were press fits. Send AP214 or AP242 plus the PDF in the same zip, same revision letter. Photos and STL files can help a human recognize the part. They do not replace the drawing that incoming QA will use.

What CAD formats should I send with the drawing package?

Send STEP AP214 or AP242 plus a PDF. IGES or X_T can travel with them. Do not send STL as the only 3D file. Native SolidWorks, Creo, or NX is optional and only useful if the shop has that seat. Export from the released configuration so toolbox holes and suppressed cuts are not missing. If you have left-hand and right-hand versions, two STEPs with two PDFs beat one file with configs the receiver cannot see. Mesh formats are for viewing on a phone, not for CAM.

Should the model or the PDF govern if they disagree?

Write the rule on the drawing. Many factories default to the model for shape and the PDF for tolerances. That split fails when a fillet exists only in one file, or when a hole moved in CAD after the PDF was plotted. A clear note is: “Drawing governs dimensions, notes, and threads. STEP governs unspecified radii as modeled, minimum 0.5 mm.” Then keep the files in sync. If you cannot write a precedence note, you are not ready to RFQ. Fix the mismatch, bump the revision, and send one pair.

Do I need GD&T or are plus/minus dimensions enough?

Plus/minus is enough for simple prismatic parts if datums are shown. Use ASME Y14.5-2018 when position or a datum scheme matters to assembly. A cover with a seal face and a hole pattern usually wants datum A on the seal and true position on the holes. A spacer with one functional thickness can live on plus/minus and ISO 2768-m. Blank title blocks with neither datums nor a general class force the shop to invent inspection. Invented inspection is how first articles pass the mill and fail your CMM.

How do I specify anodize in the drawing package?

Call Type II or Type III, color, thickness, masking, and before/after coat. Point to MIL-A-8625F (1993) if that is your spec. Type II build is commonly 5-25 µm. A locating bore at ±0.01 mm cannot absorb that range if you measure after dye. Mask the fits or dimension before coat. Name which holes take plugs. If you need a conductive pad, show it. “Anodize black” with no type is not a finishing spec. Put the same words in the RFQ header so the estimator does not quote as-machined.

What general tolerance should I put in the title block?

Name ISO 2768-m per ISO 2768-1 (1989) for unmarked sizes. Then put real numbers on fits. Medium class is a mill-friendly default: ±0.1 mm on small sizes, ±0.2 mm on 6-30 mm, wider on long plate lengths. Fine class is tighter and still far from a 5 µm fit. Do not put ±0.02 mm on every title-block dimension unless you will inspect every face. Tight defaults buy CMM time. They do not make a pocket wall more functional. If your company standard is a different general class, write that standard’s name so the shop does not assume ISO 2768-m.

Can I send a screenshot or a PDF export of the 3D view instead of a drawing?

No for a production quote. A shaded view does not carry datum frames, thread classes, or revision history. It is useful as a fifth file so a salesperson recognizes the part. It is not the file CAM and incoming QA will balloon. Export a real 2D drawing with views, a title block, and notes. If your CAD only plotted an isometric, you are missing hole depths and tap notes. Take the extra hour in CAD. It is cheaper than a requote after DFM.

What if I still have an old Rev B PDF in the folder?

Delete it from the zip. Do not “include it for reference.” Estimators open the first PDF they see, and purchasing may forward the wrong one. Keep Rev B in your PDM, not in the RFQ. Put Rev C in the STEP name, the PDF name, the title block, and the email subject. Freeze, zip, send once, and bump the letter when a hole changes.