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