This article is for people new to metalworking.
Murphy's Law states that when you drill a hole, it will be in the wrong place. But if you drill a hole that passes through two objects at the same time and place, it is one hole so must be in exact alignment with itself. Furthermore, if you lock these holes in the two objects together and repeat the process, the second set of holes must be in perfect alignment with each other and with the first set of holes. You can drill any number of holes and they will all be in alignment without doing any precision measuring.
Did I confuse you? This concept is better explained in the text.
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