Every CNC quotation starts with a drawing. The more complete the information, the more accurate the price and lead time. Incomplete drawings lead to back-and-forth communication, assumptions, and ultimately — unexpected costs.

We process quotation requests daily, and certain issues come up again and again. Here is what we look for in a drawing and how you can prepare yours to get a fast, reliable quote.

1. File format

We accept most standard CAD formats. The preferred option is a 3D STEP file (.stp or .step) combined with a 2D PDF drawing. The STEP file allows us to load the geometry directly into our CAM software and get accurate machining time estimates. The PDF gives us tolerances, surface finish specs and notes that the 3D model alone cannot convey.

2. Material specification

Specify the exact material grade, not just the generic family. "Steel" can mean anything from S235JR to 42CrMo4. The difference in material cost can be 3x, and the machining parameters change completely.

Clear material callouts we work with daily:

• S235JR / S355J2 — structural steel, most common for general components
• C45 (1.0503) — medium-carbon steel for shafts, gears, load-bearing parts
• 42CrMo4 (1.7225) — alloy steel, heat-treatable, high strength
• AISI 304 / 316 — stainless steel, corrosion-resistant applications
• EN AW-6082 T6 — aluminium, good machinability and strength
• CuZn39Pb3 (CW614N) — brass, excellent for turned parts

If you are unsure about the exact grade, describe the application — operating temperature, load, corrosion exposure — and we will recommend a suitable material.

3. Tolerances

This is where the biggest cost differences come from. A shaft with a ±0.1 mm tolerance and the same shaft with ±0.02 mm can differ 40% in price. Not because the tighter tolerance is difficult, but because it requires more careful setup, slower feeds, and inspection time.

Our guideline for tolerance specification:

Apply tight tolerances only where the function requires them. General dimensions work fine at ±0.1 mm. Over-tolerancing every feature increases cost without improving the part.

4. Surface finish

If the drawing does not specify surface roughness, we machine to a standard Ra 3.2 μm or better — a clean machined surface suitable for most industrial applications.

For parts that need a specific finish, indicate the Ra value on the drawing:

• Ra 6.3 μm — rough machined, non-critical surfaces
• Ra 3.2 μm — standard machined finish (default)
• Ra 1.6 μm — fine finish, sealing surfaces, sliding fits
• Ra 0.8 μm — precision finish, bearing contact areas

If the part will be powder coated, note that on the drawing as well. We can prepare the surface in-house before coating.

5. Quantity and annual volume

Quantity directly affects pricing. A single prototype has a much higher per-unit cost than a batch of 500 pieces because the setup cost is spread across the volume. If you know the annual volume, include it — we can offer a serial production price based on recurring orders.

We typically ask for:

• Quantity for the current order
• Expected annual volume (if applicable)
• Delivery schedule — all at once, or in call-off batches?

6. Additional operations

If the part requires anything beyond machining, mention it upfront. We handle these in-house, which can reduce your lead time and logistics cost:

• Powder coating — specify RAL colour if known
• Welding — include weld symbols and WPS requirements on the drawing
• Heat treatment — specify hardness requirements (HRC range)
• CMM inspection — we provide measurement reports with every batch by default

Quick checklist

Before sending your RFQ, verify your drawing includes:

1. 3D STEP file + 2D PDF drawing
2. Material grade (DIN/EN/AISI standard)
3. Tolerances on functional dimensions
4. Surface finish where relevant (Ra value)
5. Quantity + expected annual volume
6. Additional operations (coating, welding, heat treatment)
7. Delivery address and desired delivery date