When reviewing CNC enquiries, we see documents every day that unnecessarily cost time and money, not because of the parts themselves, but because of avoidable ordering mistakes. Here are the 5 most common pitfalls and how to avoid them.
Mistake 1: Missing or Unclear Tolerances
If no tolerances are specified on the drawing, most shops manufacture to ISO 2768-m (medium). This can mean a 50mm dimension may vary by ±0.3mm. If that's too much for your part, specify critical dimensions explicitly.
Mistake 2: Wrong File Format
The manufacturer ideally needs a 3D STEP model (.stp/.step) plus a 2D drawing with tolerances and surface specifications.
Mistake 3: Unrealistic Lead Times
Many shops plan 2-3 weeks for CNC parts. Faster is often possible but usually costs extra. If it is urgent, put your target date in the enquiry and we will look specifically for a shop that can meet it.
Mistake 4: Material Not Specified
"Made of stainless steel" is not enough. Specify the material number (e.g., 1.4301 instead of "V2A").
Mistake 5: Unclear Quantities
The quantity determines the price per part significantly. Specify your annual demand. Framework agreements with better conditions are arranged directly with the partner shop.
Questions about ordering? Contact us, we're happy to help with optimal specification of your CNC parts.
Frequently Asked Questions
What file format do I need for CNC parts?
Ideally a 3D STEP model (.stp/.step) plus a 2D drawing (PDF) with tolerances and surface specifications. STEP is the universal exchange format accepted by all CNC manufacturers.
How long does CNC manufacturing take?
The partner shop states the lead time in its quotation. It depends on complexity, quantity, material and workload. If it is urgent, put your target date in the enquiry. We will then look specifically for a shop that can meet it. See our cost guide for single parts vs. series.
At what quantity do CNC parts get cheaper?
From 5 pieces, unit costs drop significantly. The sweet spot for small series is 5-500 pieces. Details in our material selection guide.