GUIDES
FUNDAMENTALS OF
DRILLING & TAPPING
ON SALE NOW
FUNDAMENTALS
OF THREADING ON A LATHE
ON SALE NOW
FUNDAMENTALS OF
WORKING BETWEEN CENTERS
ON SALE NOW
FUNDAMENTALS
OF MILLING
COMING SOON
FUNDAMENTALS
OF SAWING
COMING SOON
METALWORKING
SHOP TERMS
COMING SOON
TESTING LOCATION OF CENTERS:
When the centers have been located, test them for
accuracy before drilling and countersinking them. The usual procedure is to
indent them with a center punch deeply enough so that the work can be held
lightly between the lathe centers as shown below. By holding a piece of chalk
stationary against the work (preferably on a rest), and spinning the work as
shown in the illustration, any high spots can be clearly marked at either end of
the piece and determined whether the centers have been located within sufficient
accuracy. Remember that absolute accuracy is not required, nor, in fact, likely
to be attained; but the more accurately located the centers are, the better the
job will be. It is often necessary to change the location of one or both of the
center punch marks before drilling. A satisfactory method of doing so is to hold
the work firmly in a vise, and by means of a center punch held at an angle,
drive the center to be moved in the desired direction.
