AMMCO 4850 Brake Drum Grinder User Manual

904850

Brake Drum Grinder

Installation and

Operation Instructions

with Maintenance Instructions

and Parts Identification

READ these instructions before placing unit in
service. KEEP these and other materials delivered
with the unit in a binder near the machine for
ease of reference by supervisors and operators.

1601 J. P. Hennessy Drive, LaVergne, TN USA 37086-3565 615/641-7533 800/688-6359 Manual Part No.: 921203 07
HENNESSY INDUSTRIES INC. Manufacturer of AMMCO

®

, COATS®and BADA®Automotive Service Equipment and Tools. Revision: 10/06

®

The No. 904850 Brake Drum Grinder
is a precision grinder used in brake
drum refinishing. The high-speed
grinding wheel produces a very even
finish on the drum braking surface by
grinding away any raised hard spots
that have not been removed in nor­mal machining with the carbide cut­ting tool.

2 •

AMMCO Brake Drum Grinder

GRINDER INSTALLATION

After the first brake drum has been turned, remove

the boring bar from the clamp and place the grinder in
position, Fig. 1. DO NOT overtighten the clamp on
the grinder spindle housing. For proper setup, be
sure to move the lathe spindle manually to its full back
position. DO NOT plug in the grinder power cord

until the grinder is completely setup.

Figure 1 - Grinder Installation

MOUNTING THE GRINDING WHEEL

To mount the grinding wheel, insert the Grinding
Wheel Removal Tool, (Item 28) on the parts drawing,
through the spindle housing to lock the spindle. Install
the new wheel, Fig. 2.

Figure 2 - Mounting The Grinding Wheel

Before proceeding further, the grinding wheel must
be dressed. Dressing cleans, shapes, and trues the
surface of the grinding wheel. Refer to the instruction
sheet for the No. 906061 Grinding Wheel Dresser
(PN/921109).

SAFETY PRECAUTIONS: When dressing a grind­ing wheel, extra care must be taken to protect the
operator. The lathe must not be turned on while
dressing the grinding wheel with a drum-mounted
dresser. Be sure the dresser is removed from the
drum before starting the lathe.

GRINDING WHEEL DRESSING

The No. 906061 Diamond Wheel Dresser is used to
true the surface of the grinding wheel to be parallel
with the surface of the machined drum. The diamond
nib cleans and shapes the wheel to assure full grind­ing wheel contact.

The grinding wheel is normally dressed one time to

finish grind one set of brake drums. However, if the
grinding wheel gets dull or “loaded”, redress it.
Dressing takes but a moment-don’t overlook it. Note
that the Grinding Wheel should be dressed before fin­ishing each drum.

1. The dresser is magnetically held inside the drum
on the same surface that will be ground. Visually align
the diamond tip 10-degrees below the center of the
Grinding Wheel, as shown in Fig. 3. This is particularly
important when dressing the Grinding Wheel at an
angle, Figure 4.

The Drum Grinder should be securely mounted in the

Boring Bar Clamp of the Lathe.

It may be necessary to remove the silencer band

when mounting the dresser.

Figure 3 & 4 - Visually Align Diamond Tip

2. Make sure that the grinding wheel will clear the
brake drum after it passes the diamond nib. Manually
move the lathe spindle back and forth to check this.
Use the cross feed hand wheel to adjust clearances.

CAUTION: The grinding wheel spins at a high
speed. DO NOT use a damaged wheel. DO NOT
use the grinder with the wheel guard removed.
WEAR SAFETY GOGGLES AT ALL TIMES!

3. Plug in the grinder power cord and turn the switch ON.

Use the cross feed hand wheel to move the grinding
wheel until it just touches the diamond. Using the
spindle feed hand wheel, manually move the diamond
tip back and forth across the grinding wheel face. Set
the depth-of-cut at about .005" (.127 mm) per pass.

Dress the grinding wheel until its full face is par­allel to the drum wall. DO NOT overdress or use
too fast a spindle feed. Moving the dresser across

the wheel too fast will leave too rough a surface on
the face of the wheel.

4. After dressing a wheel, do not change the position
of the Boring Bar Clamp in which the Grinder is
mounted. Remove the Dresser from the drum wall
and, after loosening the knurled set screw, rotate the
diamond nib slightly. This will help keep the nib
pointed and prolong its life — as well as set it up for
the next dressing job.

Spindle Housing

Boring

Bar

Clamp

Cross Feed Handwheel

Grinding Wheel Guard

Power Cord

Grinding Wheel

Removal

Tool

Hole

Figure 4

Figure 3