Tolerances & Precision

Understanding tolerance specifications and how they affect your manufacturing costs and quality. Choose the right tolerance level for your application.

Tolerance Levels

Standard (±0.1mm / IT12-IT14)

Included

Suitable for most applications where fit and function are important but not critical

Best For:

  • General prototyping
  • Enclosures and housings
  • Non-mating surfaces
  • Visual models

Tight (±0.05mm / IT9-IT11)

££

Required for parts with mating features or where dimensional accuracy is important

Best For:

  • Mating parts and assemblies
  • Functional prototypes
  • Mounting brackets
  • Precision enclosures

Precision (±0.02mm / IT7-IT8)

£££

High precision for aerospace, medical, or high-precision assemblies

Best For:

  • Aerospace components
  • Medical devices
  • Precision instruments
  • Critical assemblies

Ultra Precision (±0.01mm / IT6)

££££

Maximum precision for most demanding applications

Best For:

  • Ultra-precision instruments
  • Scientific equipment
  • High-end optics
  • Research components

Price Guide: £ = Budget-friendly | ££ = Moderate | £££ = Premium | ££££ = Specialist

Tolerance Capabilities by Process

ProcessTypical ToleranceBest CaseNotes
CNC Milling (3-Axis)±0.13mm±0.025mmExcellent for tight tolerances on critical features
CNC Milling (5-Axis)±0.13mm±0.025mmBetter for complex geometries with compound angles
CNC Turning±0.05mm±0.013mmExcellent for cylindrical features and diameters
Swiss Machining±0.025mm±0.005mmBest for small, high-precision parts
FDM 3D Printing±0.25mm±0.13mmGood for prototypes, not precision parts
SLA 3D Printing±0.20mm±0.10mmBetter than FDM for dimensional accuracy
SLS 3D Printing±0.30mm±0.15mmMaterial shrinkage affects tolerances

Important Considerations

Tolerance Selection Tips

  • Don't over-specify: Tighter tolerances increase costs without adding value if not needed
  • Critical features only: Apply tight tolerances only where parts mate or function requires it
  • Material matters: Some materials hold tolerances better than others
  • Feature size: Smaller features may be harder to hold tight tolerances

Geometric Tolerances

  • Flatness: Surface deviation from a perfect plane
  • Parallelism: How parallel two surfaces are to each other
  • Perpendicularity: How perpendicular surfaces are to each other
  • Concentricity: How centered circular features are

Contact Our Expert Engineers

Confused about tolerance specifications for your project? Our precision engineering team can help you determine the appropriate tolerance levels based on your functional requirements and budget. Get FREE expert advice today.

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