ANSI/ASME B1.8 Stub ACME Screw Threads

ANSI/ASME B1.8 Stub ACME Screw Threads

This Standard defines the special Stub ACME screw thread. If you are looking for data related to General Purpose ACME and Centralizing ACME screw threads you need to refer to ANSI/ASME B1.5.

The limits and tolerances in this Standard relate to single-start Stub ACME screw threads and may be used, if considered suitable, for multiple-start ACME screw threads. The latter screw threads are used to provide relatively fast traversing motion when necessary.

Only the 2G class-of-fit is specified in this standard. If an alternate class-of-fit is desired, the reader is referred back to ANSI/ASME B1.5. The 2G class-of-fit has clearances on all diameters for free movement. This screw thread relies on the screw thread flanks to maintain concentric operation.

Using the 2G class-of-fit covered in this standard some end play or backlash will result. This is unavoidable for interchangeable products. When backlash or end play is objectionable, it can be reduced by changing the class-of-fit to an alternate defined in ANSI/ASME B1.5, or by providing some mechanical means to eliminate the condition. In any case, sufficient end play must be left to provide a close running fit.

The Appendices provide text and dimensions on the following:

(a) Alternate Stub ACME Threads, Modified Form 1 and Modified Form 2

(b) Three-Wire Method of Pitch Diameter of 29 degree Stub ACME Threads

Here is a copy of the ANAI/ASME B1.8 Table of Contents

This data is accurate to the best of my knowledge as of 10/20/09.
Last Revised on:5/13/2020
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