Overview
ISO 4207:2016 defines the dimensions and basic tolerances for counterbores with Morse taper shanks and detachable pilots for general use. The standard provides metric dimensions (Table 1) and a diagrammatic figure (Figure 1) to ensure consistent tool geometry, interchangeability and fit between counterbore bodies, pilots and machine tool spindles. It is a second-edition update that adds an informative Annex linking ISO 4207 designations to the ISO 13399 data model.
Key topics and requirements
- Scope: Specifies dimensional requirements for counterbores with Morse taper shanks and detachable pilots used in general machining.
- Dimensions: Detailed in Table 1 and illustrated in Figure 1; dimensions are given in millimetres (metric units only).
- Tolerances:
- Cutting diameter (d): z9
- Pilot diameter (d1): e8
- Pilot hole diameter (d2): h8
- Morse taper: tolerance and form specified by ISO 296 (self-holding tapers for tool shanks)
- Normative references: ISO 296 is required for Morse taper specifications.
- Data mapping: Annex A provides relationships between ISO 4207 property names (e.g., cutting diameter, guide pilot diameter, overall length) and preferred symbols in ISO 13399 for cutting tool data representation and exchange.
Practical applications
- Ensures interchangeability of counterbores and detachable pilots across manufacturers and toolrooms.
- Guides tooling design, procurement and quality control in metalworking, machining and manufacturing operations.
- Used by:
- Tool manufacturers and designers specifying counterbore geometry
- Machine shops and maintenance teams selecting compatible pilots and holders
- Procurement professionals enforcing standard tool specifications
- CAD/CAM and tooling-data managers mapping tool attributes to ISO 13399 for digital tool libraries
- Supports consistent assembly and accurate hole preparation where precise pilot guidance and cutter geometry are required (e.g., reaming, boring, hole preparation before press fits).
Related standards
- ISO 296 - Machine tools: self-holding tapers for tool shanks (normative reference for Morse tapers)
- ISO 13399 (all parts) - Cutting tool data representation and exchange (Annex A mapping)
- Other complementary tooling standards: ISO 4204, ISO 4208 (referenced in ISO 4207 bibliography)
ISO 4207 is essential for organizations focused on tooling standardization, tool data management, and reliable metalworking production where Morse-taper counterbores with detachable pilots are employed.