Power Feed - Grizzly G0791 Owner's Manual

How to Read Inch Threading Chart
Figure 78 indicates the gearbox lever and end
gear positions and available TPI for inch threading.
The end gears for all inch threading operations
must be arranged as follows (see End Gears on
Page 58 for more information):
• 40T gear in upper "F" position
• 86T/91T gear in middle position, with 86T
gear mounted toward lathe
• 40T gear in lower "G", inside position
End Gear Positions
40T
86T
40T
Alpha Lever
Positions
Figure 78. Location of gearbox lever and end
gear positions on inch threading chart.
Model G0791 (Mfd. Since 9/15)
Numeric Lever Positions
Threads Per Inch

Power Feed

Both the carriage and cross slide have power feed
capability when the carriage is engaged with the
feed rod. The rate that these components move
per revolution of the feed rod is controlled by the
quick-change gearbox lever positions and the end
gear configuration.
The feed per revolution and the spindle speed
must be considered together—this is the feed
rate. The sources you use to determine the opti-
mum spindle speed for an operation will also
provide the optimal feed to use with that spindle
speed.
Often, the experienced machinist will use the
feeds and speeds given in their reference charts
or web calculators as a starting point, then make
minor adjustments to the feed rate (and some-
times spindle speed) to achieve the best results.
The carriage can alternately be driven by the
leadscrew for threading operations. However, this
section only covers the use of the power feed
option for the carriage and cross slide compo-
nents for non-threading operations. To learn how
to power the carriage for threading operations,
refer to Threading on Page 61.
If feed selection lever and half nut are
engaged at the same time, machine damage
could occur. Even though there is a lock-
out device to prevent this, it could break if
forced.
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