Most delays in machining quotes come from missing information – not from the machine shop. A complete drawing and a short request for quotation (RFQ) get you a faster, more accurate price and fewer surprises later.
Why your drawing decides the quote
A machining quote is built from three things: material, machine time and set-up effort. Every one of them comes from your drawing. When information is missing, the supplier has to ask questions or assume the worst case – and that means a slower reply or a higher price.
The drawing checklist
Before you send an enquiry, check that the drawing shows:
- All dimensions needed to make the part, with units (mm or inch).
- Tolerances – a general tolerance note (for example ISO 2768-m) plus tighter tolerances only where the function needs them.
- Material grade – for example EN8, EN19, SS304, SS316, aluminium 6061/6082 or brass – not just “steel”.
- Threads with full callouts, such as M10×1.5 – 6H, including depth for blind holes (see our thread guide).
- Surface finish requirements (for example Ra 1.6 µm) on functional faces – see surface finish explained.
- Geometric tolerances (GD&T) and datums where flatness, perpendicularity, concentricity or position matter.
- Heat treatment or hardness, if required, and whether it is before or after machining.
- Plating or coating, and whether dimensions apply before or after it.
- Edge requirements – for example “break all sharp edges 0.2–0.5 mm”.
- Revision number and date, so everyone works from the same version.
Which files to send
- PDF 2D drawing – essential; it carries the tolerances, threads and notes.
- STEP or IGES 3D model – helpful for complex VMC parts and for programming.
- DXF – useful for flat profiles and plates.
If you only have a sample part, the supplier can usually measure it and quote – but confirm the critical dimensions in writing before production.
What to include in your RFQ
Alongside the drawing, a short email or form with these details saves a round of questions:
- Quantity – and expected repeat volume, e.g. “200 now, about 1,000 per month later”.
- Target delivery date and delivery location.
- Inspection needs – such as a first-article report or a dimensional report.
- Packing requirements – rust protection, individual packing, etc.
- Who supplies the material – the machine shop or you.
Common mistakes that raise the price
- Tight tolerances everywhere. ±0.01 mm on every dimension multiplies machining and inspection time. Keep tight limits for fits and functional faces only.
- Sharp internal corners on milled pockets. A rotating cutter always leaves a radius. Allow an internal corner radius slightly larger than the cutter, where possible.
- Very deep, narrow pockets or holes. They need long tools, slower cutting and sometimes special operations.
- Unclear thread details. Missing pitch, class or depth leads to questions or assumptions.
- No material grade. “MS” or “SS” alone can mean several grades with very different prices and machinability.
For a deeper look at tolerances, read our guide to machining tolerances for buyers, and see 10 design tips for VMC machined parts for features that are cheaper to machine.
Next step
A clear drawing and a short RFQ usually get you a faster reply, a lower price and fewer surprises during production. When you are ready, send your drawing to VR Engineering with the quantity and material, and we will reply with price and lead time for CNC and VMC machining.
Frequently Asked Questions
Which file format should I send for a CNC machining quote?
A dimensioned 2D drawing in PDF is the most important file because it carries tolerances, threads and notes. If you have a 3D model, add a STEP or IGES file as well; for flat profiles, a DXF is useful.
Can I get a quote with only a sample part?
Often yes. The supplier can measure the sample and quote, but critical dimensions and tolerances should be confirmed in writing before production, ideally on a drawing.
Why does quantity change the price per part so much?
Programming, tooling and fixture set-up are one-time costs. With a larger quantity, these costs are shared across more parts, so the price per part drops.
CNC and VMC machining specialists in Metoda GIDC, Rajkot. Questions about your part? Send us your drawing.
