middle and engage the half nut. If done correctly, you will achieve the lead screw rotating
and the carriage to move left and right.
While the cross/longitudinal feed lever is in the feed position, the half nut lever (B) can be
engaged, safety interlock mechanism will prevent simultaneous engagement of (A) and (B).
For threading, put the lever (28) A B on the gear box to the right. Then move the
cross/longitudinal feed lever (A) to the middle and engage the half nut.
CAUTION: DO NOT FORCE THE HALF NUT LEVER WHILE ENGAGING WITH THE
LEAD SCREW.
When you power feed the spindle is what decides which way to engage the carriage. When
the spindle rotates clockwise, the carriage moves left. Conversely to the right.
8.6.2 THREADING DIAL
When the pitch proportion of the lead screw and work piece thread is not integer times and
need to open the half nut while cutting, it is necessary to use the threading dial to control
tools and prevent the mixed screw. The threading dial is located on the right or left side of the
apron. It performs the important function of indicating the proper time to engage the half nut
lever, so that the tool will enter the same groove of the thread on each successive cut. The
dial is marked with lines numbered 1.2.3.4. and in between are lines with no numbers. These
are half lines and are called unnumbered lines. The dial engaged with the leadscrew, causes
rotation of the dial, and a single line is marked on the housing of the threading dial (fixed
line).
The instruction plate riveted on the threading dial shows the selection and sequence of
matching the revolving lines with the fixed line.
For thread cutting, engage the half nut with the appropriate numbers shown on the scale
column of the threading dial plate. 1-4 on the scale means the half nut can be engaged on any
of the numbered lines 1-2-3-4. For each successive cut, only numbered lines must be used. 1-
3/2-4 on the scale means the half nut can be engaged on 1 and 3 or 2 and 4. For successive
cuts, when you engage the half nut on the numbered line “1” or “3” you engage the half nut
on the numbered line “2” for the first cut. After that, the half nut will be engaged on the
numbered line “2” or “4”. 1-8 means the half nut just be engaged on any line, numbered or
unnumbered.
If the half nut engages with the lead screw all the time while cutting the thread, you don’t
need to use the threading dial. After cutting, back the tool and reverse the motor, then move
the tool to the last start cutting position and make the next cut.
8.7
FOUR POSITION TOOL POST
