Patent Application
20070266835
The invention relates generally to woodworking and industrial power tools, and more particularly, to providing a cutting table surface that can be rapidly reconfigured to allow changes in the position of an alignment guide or rapid selection among multiple alignment guides.
Radial arm saws typically have a wooden table which comprises a cutting surface, an alignment fence, and a parking surface area behind the fence, and is attached firmly to the frame beneath the saw. While the saw blade is in the parking area behind the fence, an object that is to be cut may be placed on the cutting surface and pushed firmly against the fence. The fence is positioned precisely with respect to the saw blade cutting path, so that holding an object firmly against the fence will align the object for an accurate cut. The saw is then turned on, and the rotating blade moves through the fence and over the cutting surface, where it cuts the object. The blade typically passes entirely through the object that is being cut and protrudes into the cutting surface
Proper table alignment and condition is critical to the accuracy of a radial arm saw. Table misalignment, damage or warping will spoil the accuracy of the cuts. As a result, tables require carefully-machined pieces, which must be periodically replaced due to aging and use. Because of the required precision, saw tables can be relatively expensive. In addition to the expense, installing a new table also requires a time-consuming alignment process.
A radial arm saw is capable of multiple types of cuts, such as standard 90-degree cross cuts, miter cuts, bevel cuts and ripping. For the standard cuts, miter cuts, and bevel cuts, the saw blade must typically pass through the fence, from the parking surface to the cutting surface, or in the reverse direction. As a result, the fence must have a notch for each point where the blade passes through. Additionally, since the blade must often cut entirely through an object, the cutting surface itself will be scored by the blade along the cutting path. The scores in the table due to standard, miter and bevel cuts will be straight lines from the parking surface, through the fence, and into the cutting surface.
If a saw is used for only standard cuts, 45-degree miter cuts and 45-degree bevel cuts, the fence will have three notches, and the cutting surface will be scored along three lines. If however, the saw is used for multiple miter or bevel cut angles, the fence will have more notches and the cutting surface will have more scores. Eventually, the fence and cutting surface may accumulate enough notches and scores that they can no longer be used to align objects accurately.
For rip cuts, the saw motor is brought out in front of the fence, rotated, such that the blade is parallel to the fence, and fixed in place with respect to the fence. When the saw is turned on, the object to be cut is pressed against the fence and moved across the table laterally into the rotating saw blade. For ripping, the object moves, sliding along the fence, while the blade remains fixed. Since the blade must often cut entirely through an object, it will score the table beneath the blade. The scores in the table caused by ripping, however, are not the same as those for cross cuts. The scores from ripping are arced troughs, roughly in the middle of the table. Eventually, an accumulation of multiple troughs will damage the table enough to require table replacement.
Another concern for rip cuts is the span of the rip. The saw can only produce a finished, ripped piece that is as wide as the distance between the fence and the blade. Often, this distance may not be sufficient. As a result, some radial arm saw tables are designed to allow the fence and parking surface to be swapped, which increases the distance between the fence and the blade. If the width of the finished piece does not require swapping the fence and parking surface, this procedure may be avoided. However, if this procedure is needed, it presents some problems. It is not a trivial process to swap the fence and parking surface, and each time it is done, it allows for the possibility of misaligning the fence when the fence is returned to its original position. Any misalignment in the fence will result in the notches being widened the next time the blade passes through the fence for a cross cut. Widened notches may require replacement of the fence, even sooner than the cutting surface requires replacement. Additionally, the notches in a fence, that result from cross cuts, provide possible snag points when an object is slid along the fence for ripping.
Embodiments of the invention provide for a rapidly reconfigurable saw table comprising a cutting surface and a first fence that is attached to the cutting surface and protrudes on only one side. The first fence allows for object alignment on the standard cross cut side, and an obstruction-free surface on the ripping side. The table may be oriented with the first fence protruding upward for standard cross cuts or protruding downward for rip cuts. When the first fence protrudes upward, it is available for aligning objects to be cut, similar to a standard radial arm saw fence. When the first fence protrudes downward, a wider, level cutting surface is provided, because the first fence does not interfere with the ripping surface. A second fence may then be provided on the back side of the parking area, or at any other suitable location in the parking area. Since the second fence may remain in position, there is no need to swap a fence and parking surface in order to provide an alignment guide for ripping. Additionally, since the second fence is not used for cross cuts, there will not be any notches that could snag an object that is sliding along the second fence during a rip cut.
Embodiments of the invention may provide for an alignment mechanism that allows rapid reversal of the cutting surface between the standard cross cut side and the ripping side, while preserving table alignment in either configuration. For example, the table may further comprise alignment pins and alignment holes. The alignment holes may be counter-sunk on both sides of the table, such that the alignment pins do not protrude when either of the cutting surfaces is facing upward. Changing from standard cross cuts to ripping may only require disengaging the alignment pins, inverting the cutting surface, and reengaging the alignment pins. This process takes only a matter of seconds, and is considerably faster than swapping a fence and parking surface.
Embodiments of the invention may provide for placing the reconfigurable table on top of a standard table, and may further provide for alignment pins engaging the standard table. In this manner, the alignment of the standard table provides the basis for the alignment of the reconfigurable table. Further, a second parking surface may be provided, and placed on top of the standard parking surface, allowing for a parking surface that is level with the reconfigurable table cutting surface. The reconfigurable table cutting surface and second parking surface may have a thickness that approximates the height by which a standard fence protrudes above the standard cutting surface. In this manner, when the reconfigurable cutting surface is oriented for ripping, and placed against the standard fence for alignment, the reconfigurable cutting surface, top of the standard fence and second parking surface will present a roughly flush surface.
Embodiments of the invention allow for alignment pins to be placed through a standard table, abutting against the edges of a standard table, engaging another part attached to the saw frame, or attached to the saw frame itself. When the reconfigurable table requires replacement, it may be possible to simply set a new one in place over top of the standard table, without the time-consuming alignment procedure necessary when replacing a standard table. A pre-drilled reconfigurable table may reduce the precision of the cuts below what is possible with a custom-aligned standard table. However, the use of a reconfigurable table along with a standard table permits use of the standard table for situations in which the reconfigurable table's precision may not be adequate. For high precision cuts, the reconfigurable table may be removed, and the standard table may be used normally. For cuts that do not require such high precision, a less-expensive reconfigurable table may absorb most of the wear and tear from use, which would prolong the life of the standard table. Embodiments of the invention, however, may not require the presence of a standard table, but may allow a reconfigurable table to be used as the sole table.
For a more complete understanding of the present invention, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:
Holes 306a-d are countersunk so that the tops of alignment pins 305a-d do not protrude above the level surface of cutting surface 301. For clarity, alignment pin 305b is shown out of hole 306b. In
The method may also be used starting at box 55, if the table is configured for ripping. An alignment mechanism that retains a cutting surface in proper position is disengaged in box 56. In box 57, the cutting surface is inverted and set back on the saw, such that a fence protrudes upward. An alignment mechanism is engaged in box 58, to hold the cutting surface in place. At box 51, the table is configured for standard cross, miter and bevel cuts. The cutting surface may also be placed with a fence facing up, but on the front operator side of standard the cutting surface, such that fence provides a guide between the saw blade and the operator. This may provide a safety ridge.
Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the present invention, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.
