Landis Thread Cutting - Acme Threads
The Landis System for cutting Acme Threads offers several advantages compared to other methods.
Landis provides the greatest latitude in tool operation, they're the best tool for the job and they are the surest method for cutting Acme threads.
General Purpose
With clearance on all diameters for free movement, general purpose Acmes are used for a wide variety of parts including all types of vise and jack screws where holding major diameter is not a critical consideration.
Three classes of thread fit tolerances are available: 2G, 3G and 4G.
Specifications:
General Purpose Acme
Centralizing
Centralizing Acmes have limited clearance at the major diameter of screw and nut and are used extensively for
feed screws. The limited clearance enables a bearing at the major diameter to maintain alignment of the thread
axis preventing wedging on the flanks and part sagging.
Five classes are used: 2C, 3C, 4C, 5C, and 6C. Classes 5C and 6C are designed to allow limited backlash,
though some backlash will be experienced with any of these classes.
Specifications:
Centralizing
Acme
"Stub" Acme
The Stub Acme is generally used for applications where a
coarse pitch thread of shallow depth must be used due to mechanical or metallurgical considerations. A standard 1-1/2 - 5P Acme is planned for a specific part, but the amount of
metal removal would reduce the minor diameter to the point where the torque would twist the part. The solution:
use a 1-1/2", 5 pitch two start, or 1-1/2", 5 pitch Stub Acme. Thread height for Standard Stub Acmes is equal to 0.3 times the pitch, while the height of a Standard Acme is
1/2 of the pitch. Otherwise, the forms are identical.
Specifications:
Standard Acme Stub
Modified "Stub" Acme
Basic data for two other commonly used forms
have been tabulated. These are designated Modified Forms 1
and 2. Always use the Standard Stub Acme form in preference
to the Modified forms where it is practical
M1 - the pitch and minor diameters are smaller than the standard form values.
M2 - the pitch and minor diameters are
larger than the standard form values.
Specifications:
M1 & M2 Acme Stub
Diameter
Threads
