Change Gear Replacement; Thread Cutting - Jet BDB-1340A Owner's Manual

Change Gear Replacement

Note: the 32T x 127T x 48T gears are installed
in the end gear compartment when delivered
from the factory. This combination will cover
most inch feeds and threads under normal
circumstances. The additional gears found in
the toolbox are used for some metric threads
and feeds.
1. Disconnect the machine from the power
source.
2. Open the end cover on the left end of the
headstock.
3. Loosen the socket head cap screw (A, Fig.
19) and hex nuts (B, Fig. 19). Move the
quadrant out of the way.
4. Change gears (C, Fig. 19) to match the feed
and thread chart.
5. Thoroughly clean and install new gears.
6. Move the quadrant so the large gear
meshes with the smaller gears and tighten
to secure in place. Note: Make sure there
is backlash of 0.002" – 0.003" between
gears. Setting the gears too tight will cause
excessive noise and wear.
7. Close the cover and connect the machine to
the power source.

Thread Cutting

1. Set feed rate selectors (D, Fig. 20) in proper
position for the correct feed rate of the
thread to be cut.
2. Move knob (E, Fig. 20) to the "0" position to
disengage the feed rod.
3. Engage the half nut lever (F, Fig. 21).
4. The half nut lever and threading dial are
used to thread in the conventional manner.
The thread dial chart specifies at which point
a thread can be entered using the threading
dial.
5. To cut metric threads, the half nuts must be
left continually engaged once the start point
has been selected and the half nut is initially
engaged (thread dial cannot be used).
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