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QUICK FACT GUIDES FOR MACHINISTS
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GUIDES
FUNDAMENTALS OF
DRILLING & TAPPING
FUNDAMENTALS
OF THREADING ON A LATHE
FUNDAMENTALS OF
WORKING BETWEEN CENTERS
FUNDAMENTALS
OF MILLING
FUNDAMENTALS
OF SAWING
METALWORKING
SHOP TERMS
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When tapping drilled holes, if the tap cuts away metal the full form of the tap thread, the result is a 100% "height" of thread in the work. The "height" of the thread is determined by the size of the drilled hole. If the hole is the same as the minor diameter of the tap, the thread produced would be 100% height, if the hole is larger than the minor diameter of the tap, the height of the thread will be less than 100%. Thus in order to vary the height of the thread, we must vary the size of the drilled hole. In actual practice, 100% height of thread is neither necessary nor desirable in most cases. Thread strength tests clearly show that any increase in the percentage of thread over 60% does not increase the strength. For the vast majority of tapped hole requirements a minor diameter which provides a 55% to 75% thread is adequate.
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Copyright © 2002 QUICK FACT GUIDES FOR MACHINISTS
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