904850
®Brake Drum Grinder
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.
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 |
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.
Spindle Housing
Boring
Bar
Clamp
Cross Feed Handwheel
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.
Grinding Wheel Guard
Power Cord
Removal
Tool
Hole
Grinding Wheel
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 |
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Figure 4 |
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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.
2 • AMMCO Brake Drum Grinder
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