Here is a list of all the postings Jan Michael has made in our forums. Click on a thread name to jump to the thread.
Thread: Measuring Inside Diameters |
31/05/2023 20:21:20 |
I just recently received issue 328 here in North America and enjoyed reading the Artful Dodge #8 article on inside measuring. Many years ago when I was being trained to use a jig grinder by the seasoned operator he gave me hints on inside measuring. The toolroom did not have sophisticated three-point gauges so accurate hole measurement too large for pin gauges was done by telescoping gauges with expected accuracies in the tenths thousands of an inch. The process he demonstrated for me has served me well. His instructions were to set the telescoping gauge a little larger than the hole, and to tighten the locking knob enough to keep it from springing open, but not fully locked. It was then positioned vertically in the hole and tilted so the ends touched. Now for the trickier part. Pull the handle down to drag the arms of the gauge through the diameter once, AND ONLY ONCE. Pay attention to the feel of the drag as the gauge is pulled through. Now begin checking with the appropriate micrometer by waggling the gauge between the mic anvils while slowly closing it to achieve the same drag resistance feel you had in the hole you're checking. If you can get consistent readings with two or three tests and consistent drag inside and out, you can use telescoping gauges to measure to tenths. |
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