Stub Acme Thread Calculator for single start Stub
Acme threaded rod and nut dimensions. Only tolerance class 2G is established for general
usage in ASME / ANSI B1.8. If a fit having less
backlash is required, the tolerances and allowances
for general purpose thread Class 3G or 4G of ASME/
ANSI B1.5 may be used to determine the limiting
dimensions for mating threads. Stub Acme thread angle is 29° and the
thread height is 0.3 times thread pitch. When design requirements
necessitate use of a lesser or greater thread height, the
data should be obtained from the Appendix of the ASME / ANSI B1.8-1988.
Allowances, Tolerances, and Clearances for Stub Acme
Note: 1 Preferred diameters and associated pitches of Stub Acme
threads which are recommended in the ASME standard.
Note: 2 Only class 2G is established in ASME/ANSI B1.8-1988.
Note 1: d: degree , m: minute.
Centralizing Acme Threads: The tolerances of major diameter of external and internal threads are tighter with respect to
general purpose Acme threads.
In case of a lateral force, external and internal threads contact each other at the major diameter of the thread.
This helps to keep alignment of the thread axis and prevents wedging.
Gages for Stub Acme Threads:
Gages for Stub acme threads are defined in ASME B1.8 standard.
Gage tolerances, gages for Acme threaded rods and nuts including GO/NOT GO
thread ring and plug gages and necessary information related with gauging are
given in this standard.
Lead: The distance that nut advances in one revolution of the
Acme threaded rod.
Length of Engagement: The tolerances specified in the ASME B1.8-1988 standard are applicable to
lengths of engagement not exceeding twice the basic major diameter.
Major Diameter: The maximum
diameter of a thread which is diameter of the crest of a male thread or root of
a female thread.
Minor Diameter: The minimum
diameter of a thread which is diameter of the root of a male thread or crest of
a female thread.
Multi Start Acme Thread: Provides fast
relative traversing motion with lower mechanical advantage.
Stub Acme Thread: The thread height is less than general purpose and
centralizing acme threads. The thread height is 0.3 pitches for
Stub Acme thread. In general purpose form this is 0.5 pitches. Stub Acme thread form is provided for unusual applications where a coarse-pitch thread of shallow depth is required due to
mechanical or metallurgical reasons.
Thread class: A classification
system to classify the threads for interchangeability and manufacturability.
Threads per inch: Number of full
thread per an inch length.