A good CNC quote starts with a complete set of files. The fewer assumptions the machining supplier has to make, the faster and more accurately they can quote the part. An incomplete inquiry turns quoting into a series of questions: what material, what tolerance, how many pieces, does the surface need grinding.
This post is a practical checklist: which files to send, in which formats, and what to add in the body of your message. If you want to know how to prepare the drawing itself, complement it with how to prepare a technical drawing for a quote.
The minimum package for a quote
The best starter package for quoting a machined part is:
- a technical drawing in PDF with tolerances,
- a 3D model in STEP format,
- material and grade (e.g. C45, 1.4301, EN AW-6082),
- quantity: prototype, small batch, repeat production,
- required finish: surface roughness, anodising, zinc plating, passivation,
- expected delivery date.
This package makes it possible to quote most parts without follow-up questions. For multi-operation parts, the STEP model additionally helps assess the number of setups and the sequence of operations in turning and milling.
PDF, STEP, DXF — how they differ and when to use each
Each format carries different information. It is best to send them together, because they complement each other.
| Format | What it contains | When it is essential |
|---|---|---|
| Dimensions, tolerances, surface roughness, inspection requirements | Always for parts with critical requirements | |
| STEP (.step/.stp) | Full 3D geometry, independent of the CAD system | For housings, pockets, complex 3D geometry |
| DXF/DWG | 2D contour, cut and flat parts | For sheet metal, plates and contour-based parts |
Avoid sending only native formats (e.g. SolidWorks or Inventor) unless you are sure what software the supplier uses. STEP opens in every CAD/CAM system, so it is the safest carrier of geometry.
What to add beyond the files
The files alone are not everything. A few sentences in the inquiry often decide how accurate the quote is.
- Quantity, and whether production is one-off or repeat,
- material or acceptable substitutes,
- which dimensions are critical for the part's function,
- required surface finish or coating,
- deadline and the part's purpose (e.g. sliding bushing, machine component).
Example of a good inquiry: "Please quote 25 pcs of bushings in C45 per the PDF and STEP. The internal H7 diameters and Ra 1.6 surface roughness are critical. A repeat batch of 50 pcs per quarter is possible. Expected lead time: 3 weeks."
The most common gaps that slow down a quote
A few recurring gaps make quoting drag on.
- No quantity — the price of one piece and of a batch of 100 are two different worlds, because the setup cost is spread across the batch.
- Material stated as "steel" — C45, S355 and 1.4301 mean different prices, availability and machining parameters.
- The same tolerance everywhere — "everything ±0.01 mm" is often unnecessary and expensive; it is better to point out the critical surfaces.
- A model with no requirements — a STEP file alone does not say what matters for the part's function.
How these elements translate into cost is covered in how much does a CNC part cost. And if you are still choosing a supplier, how to choose a CNC machining company will help.
Decision box: is your package ready?
A quick check before sending the inquiry:
| Question | If the answer is "no" |
|---|---|
| Do I have a PDF drawing with tolerances? | Mark at least the critical dimensions and fits |
| Do I have a STEP model? | For complex geometry, export a STEP from CAD |
| Have I specified the material and grade? | State the grade or allow a substitute after consultation |
| Have I specified the quantity? | Give a range: 1, 10, 50, 100+ |
| Have I defined the finish and deadline? | Add the coating or "no coating" and the expected date |
Summary
A complete inquiry does not mean a long description. It means clear data: PDF, STEP, material, quantity, finish and deadline. This package shortens quoting time and reduces the risk of the price shifting during production.
Have your files ready? Send your project to Nomatec — we will check whether the documentation is sufficient for a quote and advise whether turning, milling or prior CAD/CAM design is the better route. If anything is missing, we will tell you what to add.
FAQ
Is a STEP model alone enough for a CNC quote?
A STEP model shows the geometry, but it usually contains no tolerances, surface roughness or inspection requirements. It is best to attach a PDF drawing as well, so the supplier does not have to make assumptions.
In what format should I send the 3D model for a quote?
STEP (.step or .stp) is the safest choice, because every CAD/CAM system can open it. Native formats (SolidWorks, Inventor) can be problematic if the supplier works in different software.
Do I need to send a drawing if I have a good 3D model?
For parts with tolerances, fits and surface requirements, a PDF drawing is needed. For simple shapes without critical requirements, a STEP alone is often enough for a preliminary quote.
What should I state in the inquiry besides the files?
Material and grade, quantity, expected finish, inspection requirements and the deadline. These details most often determine the price and lead time.
Will Nomatec help if I only have a sketch or an incomplete model?
Yes. If the documentation is conceptual, the Nomatec team will help organise the data and prepare the model and drawing before the actual production quote.
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