Zero-setting Mitutoyo micrometers


There is no easier way to make measuring errors with serious consequences than to use a micrometer that has not been set to zero. Before use, even with a brand new micrometer, be sure that it is set to zero. The manufacturer admonishes us to "observe the following points to correctly zero adjust the micrometer." .

  • Rotate the ratchet stop 1-1/2 to 2 times to exert a constant measuring force.
  • Allow sufficient time for the micrometer [to become] thermally stabilized, especially when moved from a significantly different temperature.
  • Zero adjust the micrometer in a posture in which measurements are actually performed.
  • Use a calibrated standard bar for micrometers larger than 1" (micrometer standard).

With the spindle closed on the 0-1" micrometer, or closed onto a micrometer standard for larger micrometers, the zero of the barrel should coincide with the zero on the rotating thimble. For instance, on a 1-2" micrometer you must insert a 1" standard and close the thimble. If the zeros don't line up, use the wrench which came with your tool, hook it around the barrel so it fits into the small hole and gently turn the barrel until the zeros line up. If the barrel won't budge, use the back of a screwdriver to gently tap the wrench. Old micrometers may have become corroded and the barrel won't move. In this case you'll have to send it in for reconditioning. Micrometer wrenches are available if you've lost yours.

It follows that zero-setting a 2-3" micrometer requires a 2" micrometer standard (measuring rod), a 3-4" will require a 3" measuring rod, and so forth. Further information on measuring rods can be found on page 58.

There is no question that Amazon can offer you the best prices on almost every kind of precision measuring tool. They also offer easy no-questions-asked returns and often free shipping. The small distributor simply cannot compete. That's why we include this link so you can go directly to Amazon and see what they're offering.

Two things to consider:

  • Amazon product photos sometimes don't match the product description. It's the description that you want to pay attention to.
  • There are imitation gages on the market (specifically Mitutoyo) and you can make sure you are getting the real item by looking for the words "sold by Amazon". If it is sold by a third party, you might want to call Mitutoyo to find out if they are legitimate distributors.

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