A technical drawing is the key document that determines whether a part will be manufactured correctly on a CNC mill or lathe. It defines the geometry, dimensions, tolerances and surface quality requirements. Whether created in a CAD environment or as a simple 2D drawing, its clarity and completeness have a direct impact on pricing, lead time and production quality.

At RIMET, we work daily with numerous customer projects from various industries. Below are practical guidelines that help avoid misunderstandings and speed up both quotation and production.

What should a CNC-ready technical drawing include?

A good drawing must be clear, unambiguous and complete. The less room for interpretation, the lower the risk of error.

Clear, non-overlapping views

• Views should not overlap.
  • If space is limited, include a detail view at a larger scale.

All critical dimensions

• lengths, widths, diameters, depths,
  • radii and chamfers,
  • threads with full specification,
  • through and blind holes.

Tolerances

• general tolerances,
  • critical dimensions with specified tolerances.
  Tolerances often determine the machining method and production time.

Surface requirements

• roughness (e.g. Ra 1.6),
  • information on post-processing, e.g. areas intended for anodizing.

Isometric view

Not required, but very helpful for understanding the geometry.

Material specification

Examples:
• EN AW-6061,
• stainless steel 1.4301,
• PA6 black.

Legend and units

Most commonly: all dimensions in mm.

In what format should documentation be delivered?

The most universal formats are:
• PDF – for reading and interpreting dimensions,
• STEP/STP – for verifying 3D geometry and preparing machining strategies.

PDF ensures unambiguous dimensions, while the STEP file helps detect geometric issues early.
We also work with 2D drawings, but converting them into a 3D model may extend the quotation process.

Does the drawing have to be perfect?

Not perfect, but clear and complete.

The most common documentation issues include:
• missing tolerances,
• missing material information,
• unclear hole depths,
• conflicting dimensions,
• hand-drawn sketches without scale.

Any unclear element means additional questions, which prolongs the quotation stage.

At RIMET, we always verify the drawing before starting production.

Why is it worth preparing the drawing properly?

Lower risk of errors
Even a single imprecise dimension can invalidate an entire batch.

Faster quotation and production
Complete documentation means fewer questions and quicker technological preparation.

Higher repeatability
Clear drawings help reproduce the part accurately every time.

What about hand-drawn sketches?

Many customers provide:
• scans,
• hand sketches,
• photos of workshop drawings.

We can work with them, but converting such materials into CAD or PDF:
• takes time,
• may introduce errors,
• increases preparation cost.

How does RIMET support you at the documentation stage?

• we analyse the drawing from a manufacturing perspective,
  • advise on material and machining technology,
  • prepare a 3D model if needed,
  • provide complete quality documentation (FAI, PPAP, CMM reports),
  • perform machining, injection moulding, finishing and measurements.

This ensures that your documentation and production remain consistent from start to finish.