The Burr King Model 760 is a three-wheel belt grinder designed for various grinding, buffering, and polishing applications. Manufactured in the U.S.A. by Burr King Mfg. Co., Inc., this machine is built for durability and performance in industrial settings.
Function Description:
The Model 760 operates as a continuous loop abrasive belt grinder. It can accommodate either a 1 1/2 x 60 inch or a 2 x 60 inch abrasive belt. With an optional internal grinding attachment (models 1400, 1401, 1402, 1411, or 1412), the belt width can range from 1/2 to 2 inches, and the belt length extends to 72 inches. The machine is designed to handle a variety of materials and work types, including fabrication, machining, casting, molding, welding, finishing, assembly, and research. It is suitable for use in industries such as aircraft/missile, automotive, contract manufacturing, agricultural, maintenance, recreational, job shops, foundries, construction, arts, orthopedic, dental, and medical. The grinder is equipped with an AC motor speed control, featuring a hybrid drive (KBAC Series NEMA1/IP65), allowing for variable speed operation.
Important Technical Specifications:
- Belt Size: 1 1/2 x 60 inches or 2 x 60 inches (continuous loop abrasive belt).
- Optional Internal Grinding Attachment Belt Width: 1/2 to 2 inches.
- Optional Internal Grinding Attachment Belt Length: 72 inches.
- Motor: Available in various configurations, including 1.5 HP (120V/1PH/3450RPM) for the main body, and options for 3/4-1 HP or 1.5-3 HP motors with variable speed controllers (120V or 220V cords). Three-phase controller options are also available.
- Contact Wheel Maximum Safe RPM:
- 202, 302: 10000 RPM
- 402, 502, 702, 802: 4400 RPM
- 902, 1002: 2200 RPM
- 1202: 1600 RPM
- Dimensions (M760 Line Drawing):
- Top View: 22.25 inches height, 11.25 inches width, 8.75 inches depth (mounting pattern: 3 holes, 0.375 inches diameter, 6.175 inches spacing).
- Front View: 24 inches height, 12.25 inches width, 25.50 inches depth.
- Side View: 7.5 inches height, 9.75 inches width.
- Noise Levels: Ranges from 80 to 93 decibels, consistent with industrial equipment. Operators and persons in the immediate vicinity should be protected from excessive noise levels as prescribed by OSHA regulation 29, piece 1910.95.
Usage Features:
- Belt Tensioning: The machine features a tensioning handle (P/N 737A) with a ratchet mechanism (P/N 736, 737F) for proper belt tension. Tension is adjusted by raising the handle and listening for clicks (typically three to eight clicks for adequate tension). To reduce tension, the handle is slightly raised, and a button (P/N 737B) in the center of the handle is pressed.
- Belt Tracking: A tracking adjustment knob (P/N 711) on the upper left side of the machine allows for centering the abrasive belt on the contact wheel (P/N 702). Turning the control clockwise tracks the belt to the left, and counter-clockwise tracks it to the right.
- Work Support Adjustment: The work support and work support arm (P/N 706, 705) can be adjusted to the desired position. It is crucial to ensure the gap between the abrasive belt face and the work rest is at most 1/8 inch to prevent work pieces from passing through and causing injury.
- Safety Features: The machine includes a contact wheel guard and backup platen (P/N 703, 704A, 704B), a full safety guard (P/N 742A, 742B, 742D, 742C) with a functional door latch, and pinch guards (P/N 1429) for internal grinding attachments. These guards are designed to prevent contact with moving parts and ejected debris.
- Motor Rotation: The belt should rotate smoothly in a counter-clockwise direction. If the belt runs in reverse, the motor rotation direction must be corrected by a competent electrician. For three-phase motors, any two legs of the input power lines need to be reversed. For single-phase motors, leads 5 and 8 in the motor's metal wiring box must be reversed.
Maintenance Features:
- Lubrication: Every thirty days, apply light machine oil to the rear wheel support (P/N 735) to rear wheel handle (P/N 737G) interface (two drops are sufficient). All bearings are sealed for life and require no additional lubrication.
- V-Belt Tension Check: Every thirty days, check the v-belt (P/N 729) tension. If the belt "slaps" the v-belt guard (P/N 728) when the drive motor starts, the v-belt needs re-tensioning. This is done by loosening the four bolts (P/N 2) securing the motor to the machine base (P/N 731) and sliding the motor toward the rear of the machine, then retightening the bolts.
- Cleaning: Daily vacuum or otherwise remove dust and debris build-up from the machine and the machine belt track.
- Idler Wheel Alignment: When idler wheels are removed or replaced, they must be installed in proper alignment to prevent premature failure. The upper and rear idler wheels must operate in the same plane, with their radial centers aligned. The procedure involves installing the rear and upper idler wheels with their inner bearing surfaces approximately 0.06 inches out from their respective supports, then adjusting the upper idler wheel until a straight line passes through the centers of the upper idler, contact wheel, and rear idler. The tracking control (P/N 711) is used to fine-tune the alignment.
- Abrasive Belt Replacement: Use abrasive belts that are the proper size and type, and avoid old, excessively worn, or lap-spliced belts, as these can snag work and create safety hazards. After installing a new belt, manually roll it to ensure coarse tracking. If tracking issues persist after alignment, the machine may require further maintenance or idler wheel replacement (in pairs).
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