Overview
ISO 3338-3:1996 - "Cylindrical shanks for milling cutters - Part 3: Dimensional characteristics of threaded shanks" defines the dimensional requirements for threaded cylindrical shanks used on milling cutters with shank diameters from 6 mm to 32 mm. It is one part of the ISO 3338 series (Parts 1 and 2 cover plain and flatted shanks). The document provides drawings and a tabulated set of dimensions, specifies the thread profile reference and centre‑hole requirements, and includes tolerancing guidance intended to ensure correct fit and run‑out performance in chucks.
Key topics and requirements
- Scope: Dimensions for threaded shanks of milling cutters, for diameters 6–32 mm.
- Thread profile: Threads are specified in accordance with ISO 228-1 (pipe threads where pressure‑tight joints are not made on the threads) - the standard refers users to that document for thread form and designation.
- Centre hole: Centre‑hole dimensions and types are referenced to ISO 866 (Type A) and ISO 2540 (Type B). The standard includes specific centre‑hole sizes linked to shank diameter and notes a special limitation for the 6 mm shank to obtain a cone diameter of 2.5 mm (instead of 3.35 mm in ISO 866).
- Figures and tables: Detailed figure(s) and Table 1 present shank diameter, allowable tolerances, centre‑hole lengths and thread-related dimensions.
- Run‑out tolerance note: The standard highlights the importance of run‑out tolerance between the centre hole and the shank axis to ensure correct centring in a chuck; it clarifies that chuck precision itself is not standardized by ISO 3338-3.
Practical applications
- Tool manufacturers designing and producing threaded shanks for end mills and milling cutters will use ISO 3338-3 to ensure interchangeability and correct fit.
- Quality engineers and inspection labs apply the dimensional tables to verify compliance and tolerances during incoming inspection and final inspection.
- CNC shops and tool procurement teams use the standard as a reference for matching cutters to toolholders and chucks.
- CAD/CAM engineers use the specified dimensions to model accurate tool geometry for simulation and tooling setups.
- Standards compliance helps reduce tooling incompatibility, improve run‑out control, and support reliable machining performance.
Related standards
- ISO 3338-1 - Dimensional characteristics of plain cylindrical shanks
- ISO 3338-2 - Dimensional characteristics of flatted cylindrical shanks
- ISO 228-1 - Pipe threads; dimensions and designation (thread profile reference)
- ISO 866 and ISO 2540 - Centre drills for centre holes (Types A and B)
- ISO 237:1975 is noted in the document where some dimensions are not conforming
Keywords: ISO 3338-3, threaded shanks, milling cutters, shank dimensions, centre hole, ISO 228-1, tool standards, run-out tolerance.