How to Prepare CAD Files for CNC Machining RFQ

A good RFQ starts with good files. Many delays in CNC quoting happen not because the part is difficult, but because the drawing or CAD package is incomplete, unclear, or missing key information. If you want a faster quote and fewer back-and-forth questions, file preparation matters.

This guide shows buyers what to send before requesting a CNC machining quote.

1. Send both a 2D drawing and a 3D model if possible

The best combination for CNC RFQ is usually:

• a 2D PDF drawing for dimensions and notes
• a 3D file such as STEP, STP, or IGES for geometry review

The 2D drawing tells the supplier what dimensions matter. The 3D model helps the machinist understand geometry more quickly and reduces interpretation risk.

2. Mark critical dimensions clearly

Not all dimensions are equally important. If there are features that affect fit, sealing, threading, assembly, or movement, mark them clearly. This helps the supplier focus process control where it matters most.

If critical dimensions are not clear, quote speed and part quality can both suffer.

3. Include material information

A drawing without material is incomplete for quoting. Different materials affect cost, lead time, and machining strategy. If you are still comparing materials, say that clearly in the RFQ.

Useful reference pages:

• Aluminum CNC Machining
• Stainless Steel CNC Machining
• Titanium CNC Machining

4. State quantity and project stage

A part for one prototype sample is quoted differently from a 500-piece production run. Always include:

• prototype quantity
• sample quantity
• expected production quantity
• whether the design is still being tested

This helps the supplier choose the right machining approach and pricing structure.

5. Add surface finish and tolerance notes

If the part needs anodizing, passivation, plating, bead blasting, or any cosmetic finish, include that in the RFQ. The same applies to tolerances. If the drawing only shows geometry without tolerance expectations, the quote may be incomplete or the supplier may need to ask more questions.

Related guide: CNC Machining Tolerance Guide for Buyers

6. Check the file before sending

Before submitting an RFQ, make sure:

• the latest revision is being sent
• units are clear
• material is stated
• critical dimensions are readable
• thread notes are complete
• special finish or assembly requirements are included

Simple file errors can waste days in communication.

7. If you do not have a full CAD package yet

You can still request an initial quote with:

• a sketch
• a photo with dimensions
• a marked-up PDF
• a sample image and written description

A complete CAD package is best, but an early supplier review can still help you move faster.

8. Final advice for buyers

A clean RFQ file package speeds up quoting, improves manufacturability review, and reduces misunderstanding before production starts. Even a few minutes spent checking your files can improve quote quality and reduce delays.

Ready to send your files? Upload your drawing here.