Model G0728–31 (Mfg. Since 11/11)
-27-
Adjusting Spindle
Speed
to select the correct spindle speed (rpM) for a
milling operation, you will need to: 1) Determine
the spindle speed needed for the workpiece,
and 2) configure the belts to provide the closest
calculated speed.
Calculating Spindle Speed
1. use the table in figure 31 to determine the
cutting speed or surface feet per minute
(sFM) required for the workpiece material.
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
Note: For carbide cutting tools, double the cutting
speed. These values are a guideline only. Refer to
the MACHINERY'S HANDBOOK for more detailed
information.
figure 31. Cutting speed table for hss cutting
tools.
2. Measure the diameter of the cutting tool in
inches.
3. use the following formula to calculate the
required spindle speed (rpM) for your opera-
tion:
Tools Needed
Qty
Wrench 24 mm .................................................. 2
To set the spindle speed:
1. DisConnECt thE Mill FroM poWEr.
2. release motor pulley tension by loosening
the jam nut and then the tensioner bolt (see
figure 32).
Setting Spindle Speed
3. using the table in figure 33, arrange the
belts to provide the best rpM for the cutting
operation.
4. retension the belts to the proper tension (see
V-belt Tensioning on page 34).
figure 32. tensioner bolt and jam nut location.
tensioner Bolt
A
B
I
II
III
D
C
I
II
III
A
670
G0730/31
G0728/29
320
570
230
1650
1200
1420
2520
2170
B
D
SPINDLE RPM CHART
PULLEY ARRANGEMENT
C
950
420
490
270
1720
1110
1410
3200
2050
figure 33. vertical milling machine rpM table.
Jam
nut
