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Long Island Indicator Service


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Roy Meyer and team

Compac Dial Bore Gage

Made entirely in Switzerland and formerly also sold under the name Interapid, Alina, or SPI. These gages have been discontinued. Depending on the damage, they can sometimes still be repaired. Small supplies of extensions and contact points may be available.

Important calibration information

Compac and Interapid bore gages measure by comparison and therefore must be calibrated before use by means of one of the following:

  • reference ring gage
  • fork for slip gages
  • masterpiece
  • gap gage
  • micrometer

To calibrate the bore gage, proceed as follows:

  1. Push the button in order to withdraw the movable contact and insert the measuring probes into the reference gage.
  2. Seek the return point by oscillating the probe.
  3. Turn the dial until the return point of the hand corresponds to the actual dimension of the ring gage.
  4. Fasten bezel clamp screw.
  5. Set the tolerance markers. The instrument is ready for use.

Compac model IA2A-IAP555A shown above, along with 2 of the contacts and extensions.


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