Overview
ISO 298:1973 - Machine tools - Lathe centres - Sizes for interchangeability specifies the dimensional sizes and designation rules required to ensure interchangeability of lathe centres (centres used to support workpieces). The standard covers sizes in millimetres and inches, and applies not only to lathes but to any machine tools using centres of the same type. ISO 298 defines which dimensions are necessary for interchangeability and leaves non‑interchangeable design details (for example, extracting devices) to manufacturers.
Key topics and requirements
- Designation: Centres are designated by number and type (example: “No. 3 Morse Centre”).
- Dimensional tables:
- Table 1 - sizes in millimetres for centres with Nos. 0 to 6 Morse or metric 5% taper shanks.
- Table 2 - sizes in inches for centres with Nos. 1 to 6 Morse or Nos. 1 to 3 Brown & Sharpe taper shanks.
- Taper shank compliance: Sizes for interchangeability of the taper shank with the machine conform to ISO 296 (Self‑holding tapers for tool shanks).
- Centre angle: The standard fixes the centre angle at 60° minimum. Where heavier workpieces require it, 75° or 90° minimum centres may be used but must be specifically designated (e.g., “75° Centre”).
- Scope limitation: Only dimensions essential for interchangeability are specified; detailed design features that do not affect interchangeability are excluded.
Practical applications
ISO 298 is used to ensure parts fit and function across different machines and suppliers, reducing tooling incompatibility and downtime. Typical uses include:
- Designing and manufacturing lathe centres, live centres, and dead centres that must be interchangeable.
- Selecting compatible centres for existing lathes, CNC turning centres, and other machine tools with tapered shanks.
- Quality control and inspection to verify centre interchangeability dimensions.
- Specifying tooling and spares for maintenance, rental, and aftermarket suppliers.
Who should use this standard
- Machine tool designers and manufacturers
- Toolroom engineers and maintenance technicians
- Tooling and accessory suppliers (centres, collets, adapters)
- Procurement and quality assurance teams responsible for tool compatibility
Related standards
- ISO 296 - Machine‑tools: self‑holding tapers for tool shanks (referenced for taper shank interchangeability)
ISO 298 is essential for ensuring consistent interchangeability, reliable workholding, and cross‑vendor compatibility of lathe centres and similar machine tool centres.