Abrading – Frame or mount – Portable abrader
Reexamination Certificate
2000-12-08
2003-05-27
Nguyen, George (Department: 3723)
Abrading
Frame or mount
Portable abrader
C451S358000, C451S449000, C451S349000, C451S456000
Reexamination Certificate
active
06569002
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to the field of hand-held power tools, and more specifically to a hand-held power tool suitable for sanding or rasping applications.
2. Description of the Prior Art
Woodworking as a hobby has become quite popular. Tools which were once marketed only to professional woodworkers are now conveniently available to woodworkers of all skills, from beginners to seasoned hobbyists and professionals. Hand-held power tools come in a number of different varieties suitable for professional and hobbyist applications. For instance, woodworkers are quite familiar with hand-held power tools such as drills, circular saws, plate joiners, sanders, routers, planers, etc. But due to design constraints, certain tools have been limited to bench top applications. One of these is the oscillating spindle sander.
An oscillating spindle sander is a tool which, as its name implies, may be used to sand a workpiece. A spindle typically protrudes from the bench top. The spindle is operatively connected to a motor which, through a series of belts, pulleys, gears or other transmission devices, causes the spindle to rotate. A drum is typically secured to the spindle. Sandpaper or other roughened material is applied to the drum. The rotating drum, along with the sandpaper, is brought into contact with the workpiece for sanding or removing material from the edge of the workpiece. The spindle is also caused to reciprocate in an axial direction. Otherwise, the same segment of the sandpaper would be repeatedly applied to the workpiece. This would cause premature wearing of the sandpaper, as well as the generation of excessive heat and burning of the workpiece.
To date, no commercial hand-held oscillating spindle sanders are available on the market. Instead, all of the oscillating spindle sanders are of the bench top variety. Among other reasons, one of the challenges facing a designer of a hand-held oscillating spindle sander is developing a light-weight, compact design which permits hand-held operation. Until now, no such tool had been designed to satisfy these competing criteria. Solutions have been proposed. None have been commercially viable on a large scale.
For example, U.S. Pat. Nos. 5,678,292 and 5,957,765 to Kimbel et al. disclose a hand-held machine tool which may be used for sanding a workpiece. Oscillation of the sanding tool is provided by one of several proposed oscillation devices, ranging from a swash plate to a driving disk associated with a rotating gear which is adapted to engage a disk follower member on the output shaft. In all but one of these embodiments, the drive shaft is perpendicular to the output shaft. Bevel gears are therefore needed to turn the direction of rotational power from perpendicular to parallel with respect to the drive shaft. This leads to a decrease in power efficiency compared to the configuration where the drive shaft and output shaft are parallel with one another.
Using a swash plate to create the oscillation of the output shaft unnecessarily complicates the tool. The swash plate is attached at an angle to a so-called intermediate shaft. As a consequence, the swash plate and the intermediate shaft are spaced from and parallel to the output shaft. A grooved roller is operatively coupled to the output shaft and engages the swash plate. As the swash plate rotates, the grooved roller is pulled up and down in a direction corresponding to the axis of the output shaft. This causes the output shaft to oscillate.
In an alternative embodiment where the swash plate is integrated into the output shaft, the grooved roller is replaced with a pin member which slides along the surface of the swash plate. This undesirable configuration could lead to the premature wearing of either the swash plate, the pin, or both. Further, this configuration would inevitably be relatively noisy in operation since the pin slides, rather than rolls, along the surface of the swash plate.
In all of the embodiments, the swash plate is relatively thin. The swash plate is cantilevered on the intermediate shaft. In operation of the tool, the swash plate would be subjected to significant forces resulting from the reciprocation of the grooved roller or pin member contacting the swash plate. Consequently, the swash plate arrangement is not the most effective mechanism for creating the oscillation motion of the output shaft.
The sander of the foregoing patents suffers from several other drawbacks. It does not have variable speed operation. Different wood stock has different surface hardness. Without a variable speed capability, the sander could damage softer wood or take longer to sand harder wood. Also, the sander of the foregoing patents does not include an edge guide assembly for precision sanding of straight surfaces. It also does not provide for means to attach the sander to the underside of a work table for conversion to a bench top oscillating spindle sander.
For these and other reasons, tools such as that disclosed in the foregoing patents have not been commercialized on a large scale. Professional woodworkers and hobbyists thus have been limited to bench top oscillating spindle sander applications. But, bench top applications limit the ability of the woodworker to truly enjoy the benefits of the oscillating spindle sander. With a bench top oscillating spindle sander, the workpiece must be moved relative to the sander during the sanding operation rather than moving the sander relative to the workpiece. Consequently, the oscillating spindle sanders of the bench top variety cannot be used to sand a workpiece which is not movable due to its size, weight, or installation constraints. For example, a bench top oscillating spindle sander cannot easily be used to sand solid surface sink cutouts on installed countertops, or the finished edges of an installed hardwood stair tread. Further, the oscillating spindle sanders of the bench top variety require a fair amount of dedicated shop space.
These and other disadvantages of the oscillating spindle sanders of the prior art are overcome by the invention of the preferred embodiments.
SUMMARY OF THE INVENTION
It is an object of the preferred embodiments to provide a portable, hand-held oscillating spindle sander.
It is a further object of the preferred embodiments to provide an oscillating spindle sander which has an integral dust collection system.
It is a further object of the preferred embodiments to provide an oscillating spindle sander in which the power transmission, including the oscillation, is achieved by a unique combination of elements which provide a compact construction.
It is a further object of the preferred embodiments to provide an oscillating spindle sander including a removable and adjustable edge guide assembly.
It is a further object of the preferred embodiments to provide an oscillating spindle sander having variable speed operation.
It is a further object of the preferred embodiments to provide an oscillating spindle sander which has internal support structures configured for easy assembly.
It is a further object of the preferred embodiments to provide an oscillating spindle sander which has adequate means for cooling the internal moving components of the sander.
It is a further object of the preferred embodiments to provide an oscillating spindle sander which has a thumb rest formed on the base for allowing a user to rest a thumb on the base while sanding.
It is a further object of the preferred embodiments to provide an oscillating spindle sander which has means for mounting the sander to the underside of a work table for conversion to a bench top oscillating spindle sander.
It is a further object of the preferred embodiments to provide an oscillating spindle sander which has a favorable ratio of oscillation to rotation of the sanding spindle.
These and other features, objects and advantages are achieved by a portable, hand-held oscillating spindle sander comprising a housing, a base associated with the housing for contacting the workpiece, a motor at least partially co
Carroll Craig Allen
Etter Mark Alan
Smith John Charles
Stafford Brent Edward
Stolzer James Timothy
Hunton & Williams
Nguyen George
Porter-Cable/Delta
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