AMMCO 7700 Drum and Disc Brake lathe - Manual (Page 17)

AMMCO Drum & Disc Brake Lathes • 13
12. Turn the lathe OFF.
13. If the tool bit did not scratch the brake surface
all the way around, there is runout in the rotor and/or
runout cause by improper rotor mounting. To deter-
mine if the runout is caused by improper mounting:
A. Turn the end knob on t he left tool bar
micrometer counterclockwise 1 full turn to back
the tool bit away from the brake surface.
B.Turn the rotor slide handwheel clockwise to
move the tool bit 14” toward the arbor.
C. Loosen the arbor nut and rotate the rotor 180°
on the arbor. Do not allow the adapters to turn.
Retighten the arbor nut.
D. Turn the lathe ON.
E. Turn the end knob on the left tool bar
micrometer clockwise until the tool bit makes light
contact with the brake surface. Turn the end knob
of the left tool bar micrometer counterclockwise
to withdraw the tool bit from the brake surface.
F. Turn the lathe OFF.
If the 2 scratch cuts are side-by-side, the runout is in
the rotor and not the mounting. Continue with step 14.
If the 2 scratch cuts are 180° apart, the runout is
caused by improper mounting. Remove the rotor and
adapters from the arbor, inspect the arbor and adapters
for nicks, burrs, chips, or rust, inspect the rotor bearing
races for looseness, clean all items, and remount the
rotor. Check for runout again. If runout is corrected,
continue to step 14.
Hazard Areas must be protected during
lathe operation. Keep shields and guards in
place. Keep fingers out of these areas and
away from rotating parts.
Figure 33 – Scratch Cuts
14. Turn the lathe ON.
15. Turn the end knob on the left tool bar microme-
ter clockwise until the tool bit lightly contacts the brake
surface.
16. Hold the end knob of the micrometer in place
and rotate the depth-of-cut dial to zero.
17. Turn the end knob on the right tool bar microm-
eter clockwise until the tool bit lightly contacts the
brake surface.
18. Hold the end knob of the micrometer in place
and rotate the depth-of-cut dial to zero.
Note: Once both depth-of-cut collars are set to zero,
use only the end knob to advance or withdraw the tool
bit. The collar will rotate with the knob to show the
depth-of-cut. Any other disturbance of the collar will
lose the zero position.
19. Turn the cross feed handwheel clockwise until
the outer tool bit reaches the groove at the rotor hub.
The right tool will automatically be positioned beyond
the inner brake surface.
20. Turn the end knob of each tool bar micrometer
individually to set each tool bit to the desired depth-of-
cut. Remove only enough material to clean up each
side.
21. Engage the automatic cross feed to begin the
cut.
22. When the tool bits have cleared the rotor, dis-
engage the cross feed and turn the lathe OFF.
23. Inspect the brake surfaces. If part of the surface
was not cut, leave the tool bars locked in position, turn
the lathe ON, slowly turn the cross feed handwheel
clockwise until the outer tool reaches the groove at the
rotor hub, and repeat steps 20, 21, and 22.
WARNING