Interapid Indicator with 5.5" long Contact Points

5.5" extra long carbide point with M1.7 threads suitable for use with Interapid models 312B-15 and 312B-15V

Interapid 312B-15 and 312B-15V (vertical style) already come with 2.75" long contact points.
You have the option of installing a 5.5" long point (exactly twice the length).

  • Even though the dial reads in .0005", once you install the 5.5" long contact point the graduations on the dial will be equal to .001" (There are no other options.)
You will have to make sure that whoever uses the indicator knows about the change in value. This extra long point is not sanctioned by the manufacturer. If you use it, all guarantees of accuracy are void.

Many customers use this long point for finding center and concentricity of barrels, such as rifle and gun barrels. In those cases, the value of the graduations are of little concern. Customers who have used this special point report that the indicator works fine and that the overall accuracy is not compromised.

The shaft of the point is steel and the ball is carbide with .080" diameter. The thread is M1.7 making it suitable for Interapid 312B-15 and 312B-15V indicators.

It should not be used with other Interapid models. The 312B-15 and 312B-15V have stronger hairsprings which helps overcome the extra weight of the longer points. We do not advise using this point with any other brand of test indicator.

Interapid indicator with 5.5

Horizontal model shown above.


  • Make = Interapid (Swiss)
  • Style = horizontal or vertical
  • Range = .06"
  • Dial diameter = 1.5"
  • Graduations = .0005" (see note below)
Note: Even though the dial reads in .0005", once you use the 5.5" long contact point the graduations on the dial will be equal to .001"
MTC39-55 … 5.5" extra long carbide point with M1.7 thread … $55.00 … order contact point only

  • Be sure to read the information on this page so that you understand the limitations of this indicator when it has the 5.5" long point installed. Be aware that we cannot accept returns on this item if you decide that it doesn't meet your needs.

Note: prices effective April 4, 2024

Interapid Point Length Model No. Order No.
.0005" Horizontal 2.750" 312B-15 74.111965 $478.00
see note* Horizontal 5.5" 312B-15X 74.111965X $533.00
.0005" Vertical 2.750" 312B-15V 74.111958 $478.00
see note* Vertical 5.5" 312B-15VX 74.111958X $535.00
*Note: Even though the dial reads in .0005", once you use the 5.5" long contact point the graduations on the dial will be equal to .001"

The "other" Swiss indicator still made in Switzerland.

Long Island Indicator Service
Long Island Indicator Service was founded in 1960. We provide professional repair service for precision measuring tools and gages with an emphasis on Swiss made test indicators, dial indicators, dial calipers and micrometers. We are pleased to be a recognized service partner for Brown & Sharpe.

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