Tool Setup; Spindle Speed Selection; Turning With Auto Feed; Thread Cutting - Promac GH-1440W Operating Instructions Manual

Fig 13
Face locate the workpiece for
added support.

6.3 Tool setup

The cutting angle is correct when
the cutting edge is in line with the
centre axis of the work piece. Use
the point of the tailstock centre as a
gauge and shims under the tool to
obtain the correct centre height.
Use a minimum of two clamping
screws when installing the cutting
tool to the four way tool post.
Avoid big tool extensions.
6.4 Spindle speeds selection
The correct spindle speed depends
on the type of machining, the cutting
diameter, the material to be
machined and the cutting tool.
These are recommended max.
speeds for a 50mm cutting diameter
with carbide (HM) tools:
Aluminium, brass
Cast iron
Mild steel
High carbon steel
Stainless steel
If high speed steel (HSS) tools are
used about 5 times lower speeds
must be chosen.
Generally speaking, the larger
in relation the cutting diameter,
the smaller the possible RPM.
For example:
Turning mild steel at a diameter
of 25mm allows a speed of
1600 RPM max. with carbide tool
320 RPM max. with HSS tool
To change the spindle speed:
The speed
changed when the spindle or
motor are still running.
Move the speed select levers (E, Fig
6) according to the speed you desire.
It may be necessary to turn the chuck
by hand to help the gears to engage.

6.5 Turning with auto feed

Several automatic longitudinal and
cross feeds are readily available by
selection on the gearbox handles
(G, H, J, Fig 14).
The gearbox selector handle (J) may
only be adjusted when the lock knob
(I) is in the 6 o'clock position. With the
lock knob in the 12 o'clock position the
selector handle (J) is locked.
The feed direction can be chosen with
the feed reversing lever (F, Fig 14).
1500 RPM
Move the lever (B, Fig 15):
1000 RPM
- right and up for longitudinal feed.
- left and down for cross feed.
800 RPM
600 RPM
300 RPM
The correct feed depends on the
material to be cut, the cutting
operation, the type of tool, the
rigidity of the work piece
chucking, the depth of cut and the
desired surface quality.
may never be
Fig 14
Fig 15
8
For example:
Longitudinal OD-turning, mild steel of
25mm diameter with a carbide tool at
1280 RPM and with rigid chucking.
Stock removal and roughing cut:
Depth of cut
Feed per revolution
(change gear box position D, B, and 2)
Finishing cut:
Depth of cut
Feed per revolution
(change gear box position F, A and 1)
Micro finishing and calibration cut:
Depth of cut
Feed per revolution
(change gear box position F, B and 1)
When roughing big diameters
reduce the depth of cut!

6.6 Thread cutting

Threading is performed in
multiple passes with a threading
tool. Each depth of cut should be
about 0,2mm and become less
for the finishing passes.
Set the feed rate selectors (A, B, C,
D, Fig 16) in proper position.
Fig 16
Move the knob (D) to E or C
to engage the lead screw.
A) To cut inch and metric threads
Set the machine up for the desired
threading pitch and first depth of cut.
Engage the halve nut (C, Fig 15).
The halve nut must be engaged
during the entire threading process.
2mm
0,2mm
0,5mm
0.1mm
0,2mm
0.05mm