How to Prepare a Custom CNC Machining RFQ
A clear RFQ helps us quote faster and more accurately — learn what information to include in your custom CNC machining request.
A clear RFQ helps us quote faster and more accurately
When customers send us a request for custom CNC machined parts, the quality of the RFQ information directly affects quotation speed, technical accuracy and manufacturing risk.
A CNC quote is not based only on the outside shape of a part. Our engineering team needs to understand the part geometry, material, quantity, tolerances, surface finish, thread requirements, inspection needs and application details before machining starts.
At JF Precision, we manufacture custom CNC machined parts based on customer drawings and 3D files. A clear RFQ helps us review your project faster, reduce back-and-forth communication, identify manufacturing risks earlier and provide a more accurate quotation. This guide explains what information to prepare when requesting a quote for custom CNC machined parts.
What to include in a CNC machining RFQ
Seven pieces of information cover almost every custom CNC machining request. The sections below take them one at a time.
Send a 3D file for part geometry
The 3D file shows the complete geometry of the part. It helps us understand the shape, features, holes, pockets, curves, wall thickness, undercuts and machining access — our design guide for custom CNC milled parts explains which of these features drive the cost.
Preferred 3D file formats include:
For CNC machining, STEP or STP files are usually preferred because they provide accurate solid geometry for quotation and manufacturing review.
An STL file may be useful for visual reference, but it is not ideal as the main file for precision CNC machining because it describes surface mesh data rather than precise manufacturing features. If you only have an STL file, please also send a drawing or additional dimensions when possible.
Add a 2D drawing for tolerances, threads and surface finish
A 3D model shows the shape of the part. A 2D drawing defines the manufacturing requirements.
For simple parts, a 3D file may be enough for an initial quotation. For precision parts, we strongly recommend sending a 2D drawing because it tells us which features need tight control.
A useful 2D drawing should include:
Critical dimensions
Tolerance requirements
Thread specifications
Hole depth and bore requirements
Surface roughness requirements
Datum references and GD&T if required
Material grade
Heat treatment or surface treatment notes
Without a 2D drawing, the supplier may not know which dimensions are functional and which dimensions can follow general machining tolerance. This can lead to unnecessary cost, unclear inspection standards or rework after production.
Specify material and quantity
Material and quantity are two of the most important RFQ details.
Material affects machinability, raw material cost, tool selection, cutting speed, surface finish, tolerance stability and lead time. Quantity affects setup cost allocation, production planning, inspection method and unit price.
When sending an RFQ, please provide the exact material grade if possible. For example, instead of writing only "aluminum," write "Aluminum 6061-T6" or "Aluminum 7075" if the grade is confirmed. If the material is not fixed yet, you can tell us the application, and our team can help review possible material options.
| RFQ Information | Why It Affects Quotation |
|---|---|
| Material grade | Affects raw material cost, cutting conditions, tools, surface finish and tolerance stability. |
| Quantity | Affects setup cost, batch planning, unit price and delivery schedule. |
| Prototype or production stage | Helps us decide whether speed, testing, repeatability or documentation is the priority. |
| Material certificate requirement | Affects material sourcing, traceability and documentation preparation. |
| Delivery target | Helps us evaluate scheduling, production priority and shipping method. |
Mark critical tolerances clearly
Not every dimension on a custom CNC part needs the tightest tolerance.
Overly tight tolerances on non-functional features can increase machining time, inspection cost and production difficulty without improving the final part performance. Clear tolerance information helps us focus control on the dimensions that matter most.
Critical tolerances are usually related to:
If you are not sure which dimensions should be critical, you can explain the function of the part. Our engineering team can review the drawing and help identify potential manufacturing or inspection risks before production.
For dimensions without special tolerance requirements, general machining tolerance may be used according to the drawing note or agreed standard.
Confirm surface finish and post-processing
Surface finish and post-processing should be confirmed before quotation because they can affect cost, lead time, appearance and final dimensions — for coated parts the coating allowance has to be agreed at this point.
Common surface finishing options for CNC machined parts include:
For precision parts, it is important to confirm whether key dimensions should be measured before or after surface treatment. Some coatings or treatments may change the final dimension, surface texture or assembly fit.
If color, texture, corrosion resistance, wear resistance, electrical conductivity or insulation is important, please include this information in the RFQ. See all options on our Treatments & Finishes page.
Tell us the application if it affects function
Application information is not always required, but it is very useful when the part has functional requirements.
For example, the same material and tolerance may behave differently depending on whether the part is used for sliding, sealing, positioning, insulation, heat transfer, vibration, load-bearing or visual appearance.
Useful application notes may include:
The part is used in an assembly
The part needs to fit with a shaft, bearing, screw or housing
The part needs to slide, rotate or seal
The part is used for electrical insulation or conductivity
The part must resist wear, corrosion, heat or chemicals
The part has cosmetic surface requirements
The part will be used as a fixture, bracket, adapter, connector or housing
When we understand the application, we can provide better DFM feedback and help reduce manufacturing risk before machining starts.
Request inspection documents when needed
For many custom CNC parts, especially overseas orders, inspection documents help confirm that the parts meet the drawing requirements before shipment. See what an inspection report contains.
Depending on the project, customers may request:
If your project requires inspection reports or material certificates, please mention this in the RFQ. This helps us plan the inspection method and documentation before production begins. See more on our Inspection Capabilities page.
RFQ checklist for custom CNC machined parts
Use the checklist below when preparing a custom CNC machining RFQ for JF Precision.
| RFQ Item | Required? | Notes |
|---|---|---|
| 3D file | Recommended | STEP / STP / IGES / X_T preferred for part geometry. |
| 2D drawing | Strongly recommended | Needed for tolerances, threads, surface finish and critical dimensions. |
| Material | Required | Include exact grade if possible, such as Aluminum 6061-T6 or Stainless Steel 304. |
| Quantity | Required | Specify prototype, small batch or production quantity. |
| Surface finish | If needed | Anodizing, plating, polishing, passivation, painting, etc. |
| Critical tolerances | If needed | Mark functional dimensions clearly on the drawing. |
| Application notes | Optional but useful | Assembly, sealing, sliding, insulation, conductivity, wear resistance, etc. |
| Inspection requirement | If needed | Dimensional report, CMM report, material certificate or QC photos. |
| Delivery target | Optional | Helps production scheduling and shipping planning. |
| Shipping destination | Optional | Useful for logistics review and delivery estimate. |
Common RFQ mistakes to avoid
To reduce quotation delays, try to avoid the following common RFQ problems:
Sending only a photo without dimensions
Sending a 3D file without material or quantity
Not specifying the material grade
Not marking critical tolerances
Using very tight tolerance on every dimension without functional need
Not specifying thread type or thread depth
Not confirming surface finish or post-processing requirements
Sending a 3D model and 2D drawing that do not match
Not mentioning inspection reports or material certificate requirements
Not providing a target delivery date when timing is important
If you are unsure about any requirement, you can still send us your files and explain the current project status. Our team can review the information and ask for the missing details if needed.
Example: A complete CNC machining RFQ
Below is a simple example of a complete custom CNC machining RFQ.
| RFQ Field | Example Information |
|---|---|
| Part type | Custom aluminum bracket |
| 3D file | STEP file attached |
| 2D drawing | PDF drawing attached with tolerances and thread notes |
| Material | Aluminum 6061-T6 |
| Quantity | 20 pcs for first batch |
| Surface finish | Black anodizing |
| Critical tolerance | Hole position and mounting surface flatness marked on drawing |
| Inspection | Dimensional inspection report required |
| Application | Used as a mounting bracket in automation equipment |
| Delivery target | Quote with standard lead time and fastest available option |
This example RFQ includes all essential information. A quotation team can review the files, understand the material choice, plan the production schedule, and provide a fast and accurate quote.
FAQ: Custom CNC machining RFQ
Questions about RFQs or lead times? Our FAQ page answers more common questions.
Please send a 3D file such as STEP, STP, IGES or X_T. For precision parts, please also send a 2D drawing with tolerances, threads, material and surface finish requirements.
A 3D file may be enough for a preliminary quote on simple parts. However, a 2D drawing is strongly recommended when the part has tight tolerances, threads, special surface finish requirements, inspection needs or functional dimensions.
The 2D drawing tells us which dimensions are critical and how the part should be inspected. The 3D model shows geometry, but it does not always define tolerances, threads, surface roughness, datum references or post-processing requirements.
You can explain how the part will be used and which features affect assembly or function. Our team can review the design and help identify which dimensions may need tighter control.
Yes. Material certificates can be provided when required, especially for production orders, application-critical parts or projects that need traceability.
Yes. Depending on the project, we can provide dimensional inspection reports, CMM inspection reports, surface roughness testing, thread gauge confirmation, QC photos and packaging photos.
Continue reading
Custom CNC Machined Parts
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CNC Machining Inspection Reports
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