Smithy GN1300 - Manual (Page 80)

If slippage occurs during your threading operation adjust the safety clutch by
turning each setscrew one at a time a half turn each time untill the clutch is
solid and no slippage occurs. Do not bottom the screws completely of the clucth
will not work.
An approximate initial setting is when the set screws have two threads exposed
from the surface of the clutch housing.
Basic Threading
Refer to a machining reference guide such as the Machinist Ready Reference for
threading theory and spindle speeds based on the material type and diameter
that you will be machining.
Step 1: Select the thread pitch which you want to cut from the chart located
on the headstock of your Granite series machine (The is also reprinted on page
8-5 of this manual.) Chose the desired pitch from the chart and follow the
horizontal row and vertical columns to set the correct positions for selector
levers (1-7) and selector lever (I-III).
Step 2: Consult the thread chart on the headstock support column for the
thread pitch that you wish to cut. The bottom row of the chart will show you
the gear set-up inside the pulley box that is required to cut the desired thread
pitch.
Figure 10.1 Leadscrew Safety Clutch
Figure 10.2 Selector Lever (1-7) & Selector Lever (I-III)
10: Threading
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