Grizzly G4002 Owner's Manual page 29

The threading dial cannot be used when
cutting metric threads. Once the half nut
has been engaged, it must remain engaged
throughout the threading process.
Half Nut Lever - this lever compresses and
releases the half nut that engages the leadscrew.
see figure 21. the lever is only engaged while
turning threads in stock. A lockout device featured
in the lever mechanism engages when the feed
selector is used.
Do not simultaneously engage the feed
lever and the threading lever. Doing so will
damage the lathe.
dial
lever
figure 21. threading dial and half nut lever.
Threading Dial indicator - the indicator tells you
when to engage the half nut to begin the threading
process. see figure 21.
the threading dial indicator has 8 lines and four
numbers printed on the dial. An indicator mark
is positioned near the rim of the dial. the dial is
mounted on a shaft that has a worm gear mount-
ed at its opposite end.
Model G4002/G4003 (Mfg. Since 8/12)
these rest in a housing that pivots so that the
gear can be engaged or disengaged. An Allen®
head cap screw is located on the side of the hous-
ing. loosen this screw to change the positioning
of this housing.
When engaged, the dial will turn when the spindle
is turning. if the dial does not turn, readjust the
housing.
When the half nut is engaged the dial stops turn-
ing. By carefully engaging the half nut as the
appropriate line or number passes by the indicator
mark, a thread can be established and the lead
maintained through the multiple passes that are
required to cut a thread to the finished depth.
the chart listed in figure 22 shows a system for
using the threading dial indicator while cutting
inch threads.
Example:
to cut 11 threads per inch engage the half nut
when the 1 or the 3 is on the indicator mark.
determine the length of the thread to be cut. Make
a cut along the part and disengage the half nut.
return the carriage to the beginning of the cut.
Watch the dial and when the 1 or the 3 comes
around to the indicator mark engage the half nut.
repeat this process until the desired depth of cut
has been achieved.
figure 22. dial indicator chart.
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