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ASME B5.50 1994 Edition, 1994
Complete Document
"V" Flange Tool Shanks for Machining Centers with Automatic Tool Changers
Includes all amendments and changes through Reaffirmation Notice , 2003
Page Count:19
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This Standard pertains to the standardization of a basic tool holder shank and retention knob for numerically controlled machining centers with automatic tool changers. The requirements contained herein are intended to provide tool holder interchangeability between machining centers with automatic tool changers of various types. Dimensions for cone angle control are in accordance with the International Standard ISO-1947.

This Standard is the inch solution for a tool holder shank and retention knob assembly. This design specifies an interchangeable retention knob that utilizes a 45 deg. knob head angle to cooperate with a flexible retention device within the spindle.

The Technical Committee of ASME B5/TC 45 recognizes the ISO-7388/1-1983 Shank and the ISO-7388/2-1984 Type A Knob as the metric solution for tool holder shank and piloted retention knob assemblies.


Tool shanks according to ANSI B5.18-1972 and ANSI B5.40-1968 are not interchangeable with tool shanks established in this Standard.

Tool shank assemblies according to the ISO-7388/1-1983 Shank and the ISO-7388/2 - types "A" and "B" Retention Knob specifications are not interchangeable with the ASME specification herein because of the piloted, metric threaded retention knob and the different knob head angle designs. This also applies to additional shank and knob designs that are in the draft stages within the ISO procedure. Accordingly, the reader should note the warning statement included with the retention knob specifications shown in Table 2.


This Standard covers a basic tool holder shank with an "inch" threaded retention knob with 45 deg. knob head angle that is applicable to general purpose machining centers where loading and exchange of tool holders is accomplished by automatic means. The term general purpose is intended to differentiate between machine designs for unusually high accuracy requirements or designs intended to function with exceptionally high spindle rotational speeds coupled with higher axis feed rates such as is normally found in High Speed Machining.

Tool shanks made to this Standard also permit use with certain front flange locking mechanisms.