Mahr Federal Indicators are extremely versatile precision measuring instrument to be employed in production and in inspection rooms.

• A complete product range of both Digital and Dial Indicators plus a wide range of accessories that offers the best solution for every measuring task
• All Digital Indicators have practical measuring functions and are equipped with a data output for easier measuring value evaluation
• Mechanical Dial Indicators possess a highly precise movement, also available are a shockproof and a waterproof version, etc.

Selecting the right ANSI/AGD type

Since modern manufacturing involves a wide range of tolerances, choosing a dial indicator might be difficult, especially since the 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 Federal, 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 Federal's "C" size bezels (NSI/AGD Group 2), which have a diameter of 2-1/4in, 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 chose, select the range per revolution which allows the tolerance spread to occupy 1/10 to 1/4 of the dial.
• Total Range — the maximum distance over which the indicator spindle can travel. Usually, this represents 2-1/2 revolutions of the hand, which is adequate for most needs. Sometimes, however, this may not be adequate for your application and a special total range may be necessary.

Your tolerance spread is .006in. You have chosen an ANSI/AGD Group 2 (Mahr Federal "C" Size) dial with a minimum graduation value of .0005in. Mahr Federal offers four indicator types in this size and minimum graduation value. Of these, type C5M has a range per revolution of .030in which is about midway between your tolerance extremes.

You selected a C5M indicator. Your total range, however, needs to be at least .200in so the spindle can clear the lip of your part. But, the longest range available in the C5M indicator you need is only .075in. Special ranges up to .400in are available for this indicator type. Select the closest range for your application (for Model C5M, you would select .250in). If the range you need is not listed under the "Special Ranges" category, contact Mahr Federal. Chances are we can supply the range you need. If your tolerance spread is .006in (±.003in), then, the most suitable minimum graduation value is .0005in.