AMMCO 3860 Drum & Disc Brake Lathe - Manual (Page 11)

Reading the Drum Depth-of-Cut Micrometer Dial
The drum depth-of-cut micrometer dial is located on the hand-
wheel. The dial has an inch scale (metric on export models) and
is used to select the amount of material to be cut from the
inside drum diameter.
(3850 ONLY) The divisions on the handwheel inch scale are
equivalent to 0.002”. A 0.010” cut (five micrometer divisions)
from an 8” drum will result in a refinished diameter of 8.010”.
(3860 ONLY) The divisions on the micrometer dial of the
adjustable drum boring bar indicate actual depth of cut. A 0.010"
cut (five micrometer divisions) from an 8" drum will result in a
refinished diameter of 8.020".
Arbor Installation
The 1” arbor shipped with the lathe has been carefully
matched to the spindle of the lathe during final assembly and
testing. Witness marks have been etched onto the arbor and
spindle for repeatable, precise alignment. This controls arbor
runout (
≤
0.001”) when changing arbors. New arbors should be
indicated and marked.
The witness marks should be carefully aligned when installing
the arbor. A true running arbor is essential to professional qual-
ity brake drum and rotor reconditioning.
The drawbar, which can be tightened or loosened at the rear of
the spindle, pulls the hardened and ground taper of the arbor
into the ground taper seat of the spindle.
1. Insert the draw bar into the spindle from the pulley end of
the spindle. Pulley cover must be on the lathe before installing
the drawbar.
2. Insert the tapered end of the arbor into the tapered seat of
the spindle. Be certain that the tapers are clean.
Important: It is essential that the tapers be thoroughly
cleaned. Chips and debris embedded into the arbor or spindle
causes poor operation, and will void the warranty.
3. Line up witness marks on the arbor and spindle.
4. Tighten the arbor onto the drawbar by holding the arbor in
place – with witness marks aligned – and tightening the draw-
bar with a wrench. As the draw bar is tightened, it will pull the
tapered adapter end into the tapered seat of the spindle.
Tighten to 50 foot pounds.
Important: Do not use wrenches or pliers on the arbor shaft
to hold it in place. This may chip, scratch, or otherwise damage
the arbor.
Brake Lathes
AMMCO 3850, 3860 Brake Lathes • 5
Figure 3 - Witness Marks on Arbor and Spindle
Spindle Arbor