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Rapid Inspection

Rapid inspection of parts using a indicator can be accomplished quickly by the machinist who is producing multiples of the same parts. Using a dial comparator stand and a indicator, one can use a gage block stack to set zero. Once zero is set to the nominal size of the part, the parts can be inspected quickly using a plus or minus figure from the read out of the indicator.

Now using the gage block and the adjustment screws on the back of the comparator we can adjust the indicator to read zero. Since we must always have atleast a quarter turn of preload on the spring assembly inside the dial indicator I generally have gone for .100" being my zero. In this case we are indicating a part that should be nominally .800 with a tolerance of +/-.005.

Now that we have zeroed our indicator we can now compare parts.

As you can see the above part is .003 under our nominal size.

This part appears to be .0045 under our nominal size, however its still acceptable due to our +/-.005 tolerance.

However this part being .021 over our nominal size, is unacceptable.

Now the inspection of each part would only take seconds each, instead of a minute or 2 to use a
micrometer or other method and using this set up we can measure parts to within .0005" with relative certainty that our measurements are correct. This is due to the lack of "feel" or repeatability required when using a dial indicator over a micrometer or calipers. As the repeatability is caused by that spring preload of the indicator and is consistently repeatable for millions of cycles.

Dimitrios Simitas