Cutlery – Cutting tools – Saw
Reexamination Certificate
1997-04-16
2001-08-21
Watts, Douglas D. (Department: 3724)
Cutlery
Cutting tools
Saw
C076S112000, C083S520000, C264S252000
Reexamination Certificate
active
06276064
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a viewing window for a power tool guard and, in particular, a viewing window which allows an operator to see a moving cutting tool of the power tool.
One of the problems associated with the use of hand-held power tools is properly aligning the cutting tool of the power tool so that the desired cut is achieved. One particular type of power tool that this problem is especially prevalent with is a hand-held circular saw. When using a hand-held circular saw, an operator normally will draw a line on the workpiece indicating the direction and pattern of cut. Circular saws typically have an upper saw guide which encases an upper peripheral portion of the blade. This upper saw guide prevents the operator from seeing whether the blade itself is actually following the marked cut line. Therefore, problems arise when the user initially attempts to align the saw blade with the cut line and further continues as the user attempts to keep the blade tracking upon the cut line.
Attempts have been made in the past to allow the user of a saw to view the blade of the saw through the guide and thus determine if the blade is properly tracking along the desired cut line. One such device is disclosed in U.S. Pat. No. 4,450,627. This patent discloses a circular saw with a clear viewing window on the upper saw guard. The structure disclosed in this patent suffers from various disadvantages. More specifically, the window is disclosed as being made of a transparent plastic material. First, plastic materials typically are susceptible to being electrostatically charged such that dust particles are likely to be attracted to the plastic surface. Thus, dust particles generated during the sawing operation are attracted to the plastic window due to the window maintaining an electrostatic charge. As is apparent, this static-induced dust contamination of the transparent window results in the operator not being able to see the blade as it passes through the workpiece, thus preventing the window from being effective. An additional problem associated with plastic windows is the fact that they are more susceptible to being scratched if the window is wiped clean of dust particles. More specifically, attempting to wipe the window of dust particles with a cloth will result in the dust particles digging into the soft plastic material, thus resulting in marring and scratching of the window. This marring and scratching, again, will obstruct the operator's view of the saw blade through the window. Therefore, a window construction is needed which will reduce the problem of static-induced dust contamination and, further, which will be resistant to scratching during a manual cleaning operation of the window.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a viewing window for the guard of a power tool which is resistant to the collection of dust thereon due to static electricity.
It is another object of the present invention to provide a viewing window which can be easily cleaned of dust and other particles without marring or scratching the surface of the window.
A further object of the present invention is to provide a window with improved longevity for covering the aperture formed in the guard even if impacted by projectiles generated by the cutting tool or by external impacts to the tool housings (such as accidental drops).
Yet another object of the invention is to provide a method for making a scratch-resistant and static-induced dust contamination resistant viewing window that is efficient and cost-effective.
According to the present invention, the foregoing and other objectives are obtained by a window assembly having a glass plate with an upper surface, a lower surface, and a peripheral edge. The glass plate with the peripheral edge is configured to generally cover an aperture formed in a cutting tool guard. A plastic layer having a peripheral edge is positioned on the upper surface of the glass plate. A frame is adapted to be attached to the guard and engages the peripheral edge of the glass plate and the peripheral edge of the plastic layer. In a further aspect of the present invention, a method is provided for making a window assembly for a power tool. The method includes positioning a plastic layer on the upper surface of the glass plate. The plastic layer and the glass plate each have a peripheral edge and are configured to generally cover an aperture formed in a power tool guard. A frame is molded to engage the layer peripheral edge and the plate peripheral edge. The frame is adapted to be attached to the power tool guard so that the combined plastic layer and glass plate generally cover an aperture in the guard.
Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon an examination of the following, or may be learned by practice of the invention.
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Black & Decker Inc.
Shook Hardy & Bacon L.L.P.
Watts Douglas D.
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