RFQ PREPARATION / CNC MACHINING INSIGHTS
A capable CNC quote starts with files that describe the intended part without forcing the manufacturing team to reconstruct design intent. A 3D model establishes geometry; a controlled 2D drawing records the requirements that the model may not carry.
Send both a 3D model and a 2D PDF when possible
For most custom parts, the most useful package contains a native CAD file or neutral 3D model plus a released PDF drawing. The model helps review the overall shape, pockets, radii, and interfaces. The drawing communicates revision level, dimensions, threads, critical notes, finish, material, and quantities.
Common neutral model formats include STEP and IGES. A native CAD format can also be useful when the buyer wants to preserve design context, but the PDF drawing should remain the reference for drawing-defined requirements. The ASME Y14.5 reference provides context for the dimensioning-and-tolerancing conventions often used on technical drawings.
What each file type contributes
| File | Best use in an RFQ |
|---|---|
| STEP / 3D model | Overall geometry, feature relationships, visual review and machining approach. |
| 2D PDF drawing | Dimensions, tolerances, threads, surface finish, material and revision control. |
| DXF or DWG | Useful for profile-driven or sheet-based geometry when supplied with the required notes. |
| Assembly or reference PDF | Explains mating interfaces, orientation and functional context where needed. |
Make the PDF drawing the single source of requirements
Do not place a critical instruction only in an email or a screenshot. Put it in the controlled PDF drawing or an attached specification that is clearly named in the RFQ. This includes material grade, finish, thread callouts, cosmetic surfaces, inspection expectations, and any feature that depends on how the part functions in an assembly.
For detailed drawing preparation, see drawing details that prevent delays. If the part contains threaded features, our CNC thread specification guide explains which notes make a thread callout complete.
Use clear revision control
Give every file a part number and revision identifier. Keep the revision visible in the PDF title block, and ensure that the model filename corresponds to the same release. When an update is made after quotation, identify the changed feature instead of simply replacing files with an ambiguous “final” version.
What to include beyond geometry
- Material grade and, when relevant, stock form or approved alternative.
- Quantity for the current order and expected repeat requirement only if it is known.
- Surface finishing or heat-treatment requirement.
- Destination country and preferred shipment details for international coordination.
- Any inspection document or packaging requirement needed before production begins.
Check the exported files before sending
Open the final PDF and neutral 3D file outside the original CAD system if possible. Confirm that dimensions are readable, views are not clipped, and the model opens with the intended geometry. A quick export check prevents the most avoidable back-and-forth in an international order review.
ExactMach supports CNC milling, CNC turning, prototype machining and custom parts for drawing-defined orders coordinated around Shenzhen and Dongguan. Share the released files and requirements so the manufacturing review can focus on the part rather than file recovery.