Selecting Spindle Rpm; Setting Spindle Height - Grizzly G0720R Owner's Manual

Selecting Spindle
RPM
Closely follow the proper cutting speed and prop-
er feed to reduce undue strain on all moving parts
and increase operator safety.
Prior to milling, determine the RPM needed to
cut your workpiece, then set the RPM on the
machine.
To determine the needed RPM:
1. Use the table in Figure 14 to determine the
cutting speed required for your workpiece
material.
2. Measure the diameter of your cutting tool in
inches.
3.
Use the following formula to determine the
needed RPM for the milling operation:
(Cutting Speed x 4) / Tool Diameter = RPM
Cutting Speeds for High Speed Steel (HSS)
Cutting Tools
Workpiece Material
Aluminum & alloys
Brass & Bronze
Copper
Cast Iron, soft
Cast Iron, hard
Mild Steel
Cast Steel
Alloy Steel, hard
Tool Steel
Stainless Steel
Titanium
Plastics
Wood
Note: For carbide cutting tools, double the
cutting speed. These values are a guideline
only. Refer to the MACHINERY'S HAND-
BOOK for more detailed information.
Figure 14. Cutting speed table for HSS cutting
tools.
Model G0720R (Mfg. Since 11/10)
Cutting Speed (sfm)
300
150
100
80
50
90
80
40
50
60
50
300-800
300-500
Setting Spindle
Height
Spindle height is changed by unlocking the quill
lock and using the downfeed handles or the fine
feed knob (see Figure 15). The digital height
gauge indicates the spindle height.
To change the spindle position:
1. Unlock the quill lock lever and loosen the fine
feed lock knob.
Tip: Use the fold-out lever (see Figure 15)
for additional leverage to unlock the fine feed
lock knob if the knob is too tight. Do not use
the fold-out lever to tighten the knob.
2. Pull down on the downfeed handles to lower
or raise the spindle. Tighten the quill lock to
secure the spindle in a particular position (if
desired).
Tip: Milling with the quill fully extended can
cause tool chatter. For maximum spindle
rigidity, it is better to keep the spindle retract-
ed into the headstock as far as possible with
the quill lock lever and fine feed lock knob
tightened.
Quill Lock Lever
Fine Feed Lock Knob
Figure 15. Spindle controls.
Downfeed Handle
Fold-Out Lever
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