Use and Care Manual

Model G0720R (Mfg. Since 11/10)
-21-
Setting Spindle
Height
Selecting Spindle
RPM
Figure 15. Spindle controls.
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.
Fold-Out Lever
Downfeed Handle
Fine Feed Lock Knob
Quill Lock Lever
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 Speeds for High Speed Steel (HSS)
Cutting Tools
Workpiece Material Cutting Speed (sfm)
Aluminum & alloys 300
Brass & Bronze 150
Copper 100
Cast Iron, soft 80
Cast Iron, hard 50
Mild Steel 90
Cast Steel 80
Alloy Steel, hard 40
Tool Steel 50
Stainless Steel 60
Titanium 50
Plastics 300-800
Wood 300-500
Figure 14. Cutting speed table for HSS cutting
tools.
(Cutting Speed x 4) / Tool Diameter = RPM
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.