Smithy Midas 1220 LTD - Manual (Page 45)

instruments (Figure 10.3). Centering square or rectangular stock is done by scribing lines
from opposite corners. The intersection of these lines is the center (Figure 10.4).
Figure 10.2 Centering on round stock and
Figure 10.4 Centering on square or rectangular stock.
Figure 10.3 Use centering instruments include calipers and dividers.
After locating the center of each end, drive a starting depression for the drill into the stock
with a center punch. Check centering accuracy by placing the workpiece between the
spindle and tailstock centers. Revolve the headstock slowly against the tip of a tool or a
piece of rigidly held chalk.
The chalk should touch just the high spots (Figure 10.5). If the center is off 0.002" or
more, correct the position of the center by repunching at an angle.
Figure 10.5 When you revolve the headstock against a piece of chalk,
the chalk should just touch the high spots.
Next, drill and countersink the centers to conform to the profile of the lathe centers. This
is best done with a combination center drill/countersink held in the tailstock arbor chuck.
The centers now will take the lathe centers without play or chatter.
10: Setting Up with Centers, Collets, and Chucks
10-2 Or Visit www.smithy.com
Chalk Marks
Compound
Chalk