Delta 31-780 - User Manual

The Delta BOSS Bench Oscillating Spindle Sander, Model 31-780, is a woodworking tool designed for sanding various materials, particularly for intricate shapes and curves. This benchtop unit is engineered to provide a smooth finish while minimizing score marks and preventing clogging of the sanding drum, thanks to its oscillating action. The sander is intended for use on a solid supporting surface, or it can be attached to an optional accessory stand (Model 50-780) for enhanced stability and convenience.

Function Description

The core function of the Delta BOSS sander is to shape and smooth wood and wood products using abrasive sleeves mounted on sanding drums. The unique feature of this sander is its oscillating spindle, which moves up and down while rotating. This dual action ensures that the abrasive sleeve contacts the workpiece at different points, distributing wear evenly across the sleeve and preventing the formation of deep grooves or burn marks on the material. This results in a faster, smoother sanding process and extends the life of the abrasive sleeves.

The sander is equipped with a motor that provides a specific number of oscillating strokes per minute, ensuring efficient material removal. It is designed to be used with various sizes of sanding drums and corresponding abrasive sleeves, allowing for versatility in handling different workpiece sizes and curve radii. The table insert, which surrounds the sanding drum, is crucial for maintaining a minimum opening to prevent fingers from being pinched and to support the workpiece effectively.

Dust collection is an integrated feature of the sander. A dust chute is provided to which a dust bag can be attached, helping to keep the work area clean and reducing exposure to wood dust, which can be injurious to health. For optimal dust removal, the use of wood dust collection systems is recommended, especially in well-ventilated areas.

Usage Features

Operating the Delta BOSS sander involves several key steps and safety considerations. Before any operation, the sander must be properly assembled, including attaching the spindle adapter, sanding drum, abrasive sleeve, and table insert. The spindle adapter has a left-hand thread, requiring counterclockwise rotation for fastening. The table insert features arrows indicating its top surface, ensuring correct placement.

The sander can be used as a benchtop tool or mounted on the optional 50-780 stand. If used without the stand, it should be fastened to a firm supporting surface to prevent tipping or movement during operation. The stand itself is assembled using carriage bolts, flat washers, and nuts, with specific instructions for brace placement to ensure structural integrity.

The on/off switch is conveniently located on the sander base. To turn the sander "ON," the switch is moved to the up position, and for "OFF," it is moved down. A critical safety feature is the ability to lock the switch in the "OFF" position by removing the switch toggle. This prevents unauthorized use and accidental starting. If the toggle is removed while the sander is running, the tool can be turned off but cannot be restarted until the toggle is reinserted.

When sanding, it is crucial to feed the workpiece against the direction of the sanding drum's rotation. This ensures proper material removal and control over the workpiece. The oscillating action is particularly beneficial for sanding inside curves, providing a consistent finish. Users are advised to use clamps or a vise to secure the workpiece when practical, freeing both hands to operate the tool safely. Extra caution is necessary when sanding small pieces, and the sander should not be used for pieces too small to be held by hand.

The sander is wired for 120-volt, 60 Hz alternating current and requires a properly grounded electrical connection. The use of 3-wire extension cords with grounding-type plugs and receptacles is mandatory. Proper cord gauge selection is also important to prevent power loss and overheating.

Maintenance Features

Regular maintenance is essential for ensuring the longevity and safe operation of the Delta BOSS sander. One key maintenance task involves checking and changing the grease in the gear housing after approximately 100 hours of use. Accessing the gear housing requires disconnecting the tool from the power source, turning the machine over, loosening two screws, and removing the cover. After removing old grease, new grease should be applied, and the cover replaced.

Adjusting the spindle assembly is another maintenance feature that addresses excessive play or increased noise levels after extended use. This adjustment involves disconnecting the tool, turning it over, and carefully removing the case. The shaft must be positioned inside the center of a bracket, which is adjusted by loosening locknuts and tightening or loosening adjusting screws until the shaft is centered. After adjustment, the locknuts are tightened, and the case is reattached.

Changing abrasive sleeves and sanding drums is a routine maintenance task. This process requires disconnecting the tool from the power source, removing the table insert, and using the supplied socket wrench to remove the arbor screw (which has a left-hand thread). The old abrasive sleeve and sanding drum can then be removed from the spindle assembly, and a new sleeve can be slid onto the drum before reattaching the assembly to the spindle adapter.

Keeping the work area clean and maintaining the tool in top condition are general maintenance practices emphasized in the manual. This includes keeping tools sharp and clean, following lubrication instructions, and regularly checking for damaged parts. Any guard or part that is damaged should be properly repaired or replaced to ensure the tool operates safely and performs its intended function. The manual also provides contact information for parts, service, warranty, or other assistance, highlighting the availability of a complete line of accessories, including various sanding spindle kits and abrasive sleeves in different grits.