Page 183 - Mahr马尔量具完整

Dial Indicators per ANSI/AGD

Selecting a dial indicator

Since modern manufacturing involves a wide range of tolerances. If your tolerance spread is .006"(±.003"), then, the most suitable
choosing a dial indicator might be difficult, especially since the minimum graduation value is .0005".
number of indicators available is so vast. The following guidelines
were prepared to assist you in selecting the right model for your
application.
Consider four characteristics when selecting a dial indicator:
• Minimum Graduation Value — value of the smallest
graduations marked on the dial. From several different values
available from Mahr, select the one which is closest to 10% of the
tolerance spread of the work you are measuring. This assures that the
tolerance will span about ten divisions of the dial.
• Size — represents the bezel diameter. Make your selection on the basis
of space available for the indicator and the distance from which it will be
viewed. The Indicator photograph shown on the first page of each ANSI/
AGD Group is full scale. Simply place the page which illustrates the
Indicator at the expected viewing distance, and choose the size that
offers you the best readability and is the proper size for your fixture.
Mahr's "C" size bezels (ANSI/AGD Group 2), which have a diameter of
2-1/4”, are the most popular.
• Range per Revolution — represents the distance the spindle
travels with one complete revolution of the dial hand. From the dials
available in the size and minimum graduation value you choose, select
the range per revolution which allows the tolerance spread to occupy
1/10 to 1/4 of the dial. Your tolerance spread is .006 ". You have chosen an ANSI/AGD
Group 2 (Mahr “C” Size) dial with a minimum graduation value of .0005".
• Total Range — the maximum distance over which the indicator Mahr offers four indicator types in this size and minimum graduation value.
spindle can travel. Usually, this represents 2-1/2 revolutions of the hand, Of these, type C5M has a range per revolution of .030" which is about midway
which is adequate for most needs. Sometimes, however, this may not between your tolerance extremes.
be adequate for your application and a special total range may be
necessary. You selected a C5M indicator. Your total range, however, needs to be at least .200"
Copies of the current ANSI Standard for Dial Indicators so the spindle can clear the lip of your part. But, the longest range available in the
(ANSI B89.1.1 0-1987) are available from: C5M indicator you need is only .075".
Special ranges up to .400" are available for this indicator type. Select the closest
The American Society of Mechanical Engineers range for your application (for Model C5M, you would select .250").
ASME Order Desk
22 Law Drive If the range you need is not listed under the “Special Ranges” category, contact
Fairfield, NJ 07007 Mahr. Chances are we can supply the range you need.
(973)882-1167

Dial Types

1. Balanced (+) on right. 3. Continuous clockwise.
Normally furnished on all Group Normally furnished on Long and
0, 1, 3 and 4 ANSI/AGD Extra Long Range Indicators,
indicators only, unless otherwise unless otherwise specified.
specified. Indicates an increasing Indicates an increasing value
value when contact is depressed when contact is depressed as in
as in comparison type OD. snap direct-reading thickness gages.
and bench thickness gages.
Note: With Revolution Counter
Note: If Revolution Counter models, counter dial numbered
models are ordered, counter dial counterclockwise.
numbered counterclockwise.
2. Balanced (+) on left. 4. Continuous counterclockwise.
Indicates decreasing values when Indicates a decreasing value
contact is depressed as in when contact is depressed as
comparison bore* and depth in direct reading slot, recess or
gages. hole depth measurements.
Note: With Revolution Counter Note: If Revolution Counter
models, counter dial numbered models are ordered, counter dial
clockwise. numbered clockwise

* Will vary as dictated by motion
transfer design.

MarCator | Dial and Digital Indicators 179