Pratt & Whitney
Home  |  Contact Us  |  Tel: (800) 371-7174
For Over 150 Years, The Standard of Accuracy
Pratt & Whitney Measurement Systems, Inc.
About P&WHigh Precision Measuring Instruments & Machines, Comparators, Gages - Dimensional Metrology InstrumentsService & SupportIndustry ApplicationsSuccess StoriesNews / Press Releases
ACME Thread Measuring - Calibration
ACME Thread Measuring - Calibration

ACME Thread Measuring - Calibration


An ACME thread has a screw thread profile with trapezoidal outlines and they are commonly used where large loads or high accuracy are required; for example, in a vice or lead screw. The ACME thread has a 29-degree thread angle with a thread height half of the pitch (P/2) and where the apex and valley are flat. An ACME thread profile is typically easier to manufacture than other thread series. This thread form also allows for the use of a split nut, which minimizes nut wear, however, the radial load on the nut is greater thus minimizing efficiency. Similar thread series are the square thread and buttress thread.

Some applicable ACME formulas are:

Pitch diameter: E = M + 1.933357 * P 4.993929 * W

Best wire size: W (best) = 0.51645 * P

 

Where:

            E = Pitch diameter

            M = Measurement over wires, i.e., the machine readout

            TPI = Threads-per-inch

            P = Pitch (1/TPI)

            W = Calibrated thread wire size

 

Pratt & Whitney offers these machines suitable for ACME threads:

1.      Labmaster Universal (Models 175, 1000M,1000A)

2.      Laser Measuring Machine

3.      Labmicrometer (Models 900, 1600)

4.      Digital Measuring Machine

5.      Universal Supermicrometer (Model 501, 504)

6.      External Supermicrometer (Model B, C, PC)

ISO 17025 Accredited