3-Gage and 4-Gage Centralizing ACME Screw Thread Plug Gages
The major diameter of Centralizing
Acme screw threads has a limited clearance of both the internal and external threads. This limited clearance
is that feature which makes Centralizing ACME Screw Threads centralizing ,thus it is a critical dimension which needs to be monitored. If the Centralizing
ACME Screw Thread is manufactured without regard to the major diameter,
in all likelihood it will fail in the field because it will not
meet the original engineer's design criteria.
External Centralizing ACME Screw Thread Major Diameter
Monitoring the External Centralizing ACME Screw Thread Major Diameter
is easily done with a micrometer, or in more critical applications,
a set of GO/NOGO Plain Cylindrical Ring Gages.
Internal Centralizing ACME Screw Thread Major Diameter
Monitoring the Internal Centralizing ACME Screw Thread Major Diameter
is trickier. The internal major diameter cannot be easily measured
by direct measurement so special tools are required. Before you
ask; the standard GO/NOGO Screw Thread Work Plug Gauges do not do
this job. The gage design for standard GO work plug thread gauge
only looks at the major diameter to assure that it does not violate
the maximum material condition. The standard NOGO work plug screw
thread plug gage major diameter is designed to be only a clearance
dimension. In-depth discussion on major
and minor diameters of parts and gauges.
To monitor the internal Centralizing ACME screw thread major diameter,
additional gage member(s) are required.
3-Gage System
The system currently specified in ANSI/ASME
B1.5 is the 3-gauge system. The 3-gage system adds a third gauge,
the NOGO Major Diameter Check Gage, to evaluate the major diameter
for the minimum material condition.
The gages in the 3-gauge system are:
The standard GO Work Plug Gage which checks the internal
Centralizing ACME Screw Thread to assure that the Centralizing
ACME Screw Thread does not violate the maximum material condition.
The standard NOGO Work Plug Gauge checks the internal
Centralizing ACME Screw Thread to assure that the Pitch Diameter
has not become too large.
The NOGO Major Diameter Plug Gage checks the Centralizing
ACME Screw Thread to assure that the Major Diameter has not been
made too big.
4-Gauge System
An alternate combination of Centralizing ACME Screw Thread Gages
is the 4-gauge system. The 4-gage system is not listed in ANSI/ASME
B1.5, but is suggested by some gauge makers because it looks more
closely at the critical thread features. The two areas of focus
are the pitch diameter and the major diameter. This 4-Gage System
consists of GO/NOGO Pitch Diameter Plug Gauges in conjunction with
the GO/NOGO Major Diameter Plug Gages.
The gages in the 4-gauge system are:
The GO Pitch Diameter Plug Gage checks the internal Centralizing
ACME Screw Thread to assure that it does not violate the maximum
material condition for all attributes other than the major diameter.
It is made identical to the standard GO Work Plug Gauge except
that it has a reduced major diameter so that the GO pitch diameter
gage member does not even see the internal major diameter.
The standard NOGO Work Plug Gauge checks the internal
Centralizing ACME Screw Thread to assure that the Pitch Diameter
has not become too large.
The GO Major Diameter Plug Gage checks the Centralizing
ACME Screw Thread to assure that the major diameter is not too
small. The GO major diameter plug gauge is designed to clear all
other aspects of the Centralizing ACME Screw Thread and look only
at the Major Diameter to evaluate it at the maximum material condition.
The NOGO Major Diameter Plug Gage checks the Centralizing
ACME Screw Thread to assure that the Major Diameter has not gotten
too big. The NOGO major diameter plug gauge is designed to clear
all other aspects of the Centralizing ACME Screw Thread and only
check the Major Diameter for an oversize condition.
There are a few "brave souls" who try to make an internal
Centralizing ACME Screw Thread without the special Major Diameter
Plug Gage(s), monitoring only the wear on their cutting tool. If
you are reading this page, I am sure that you are not one of them.
If the Centralizing ACME Screw Threads require measurement by a variable thread measurement system,
special fingers can be made to monitor the major diameter.
Notice:
This website is funded by the sale of screw thread measurement tools. It will help us continue to offer this data if you allow us to have the opportunity to sell our tools to your company. If you find this information useful, please work to get Gage Crib Worldwide Inc. on the bid list for future purchases of screw thread measurement tools.
Disclaimer:
This data is provided for general information only. The intention
is to provide accurate information; regardless; errors may exist
in the supplied information. If accuracy is critical, base your
final decisions on the data provided in the root document: ANSI/ASME
B1.5; which is a copyrighted document. To purchase a copy visit
an Authorized Reseller.
Comments:
Original Posting: 10/21/2009
Last Revision: 5/15/2020
Error corrections in, or comments about, the above data can be sent
to: office@gagecrib.com
Gage Crib Worldwide, Inc.
6701 Old 28th St SE, Suite B
Grand Rapids, MI 49546-6937
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