Cutting – With means to guide moving work
Reexamination Certificate
2000-06-06
2002-03-26
Rachuba, M. (Department: 3724)
Cutting
With means to guide moving work
C083S477200, C083S467100, C083S444000
Reexamination Certificate
active
06360641
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a rip fence for use with a table saw and, in particular, to a rip fence that has a dual locking mechanism for securing the fence in position.
2. Scope of the Prior Art
Table saws of various designs include a frame and an upper surface having an opening through which a blade extends. The upper surface supports a material, such as wood, as it is pushed towards the blade for cutting. Table saws have traditionally been stand-alone pieces of equipment that are used in workshops. Because most stand-alone table saws are used in large open spaces, the dimensions of the table saw can be large enough to support materials of various sizes for cutting. Tables that are used in workshops are not readily moved from one location to another. At construction sites, it is useful to have a table saw that can be easily moved from one location to another or between different construction sites. Accordingly, smaller and portable table saws have been designed. These table saws use lighter materials and have reduced the dimensions of the frame and the upper surface to reduce the size and weight of the table saw thereby creating the desired portable table saw. The portable table saws also use a separable folding table to hold the table saw at the correct height for operation.
An integral part of most table saws is a movable rip fence. The rip fence is positioned perpendicular to the upper cutting surface and is aligned generally parallel to the position of the blade. Most rip fences are designed to span between the front edge and the rear edge of the upper cutting surface. Moreover, the rip fence can be positioned in any position along the upper surface and is secured in such a position by a locking mechanism. The rip fence is usually secured in a position a given distance away from the blade and can be put on either side of the blade. When the rip fence is secured in a position, the wood can be pushed against the side of the rip fence to slide on the upper surface to be cut by the blade. Thus, accurate and straight cuts can be made.
Rip fences of various different designs are readily known in the prior art. In addition, different methods of securing the rip fence at a given location on the upper surface, including the use of a locking mechanism, are known. One of the primary objectives for the rip fence is for it to be generally parallel to the blade so that the most accurate cuts can be made. It is known that an effective way to make the rip fence parallel with the blade is to force it to be perpendicular to the front and rear edge surfaces of the table saw. Thus, many rip fences use a front clamping mechanism and a rear clamping mechanism. The front clamping mechanism presses against the front edge surface and the rear clamping mechanism presses against the rear edge surface. In this way, the clamping mechanism aligns the rip fence perpendicular to the edge surfaces and parallel to the blade.
It is also helpful to properly align the rip fence if the front and rear clamping mechanism move simultaneously. To achieve this, rip fences typically include a handle which is connected to the front clamping mechanism and a rod that connects between the handle and the rear clamping mechanism. When the handle is in a first and released position, the front locking mechanism is positioned in a released position relative the front edge surface and the rod reduces pressure and allows the rear locking position to move into a released position relative the rear edge surface. When the handle is in a second and locked position, the front locking mechanism is positioned in a locked position along the front edge surface and the rod pushes the rear locking mechanism into the locked position. As the handle moves from the released to the locked position, the front and rear clamping mechanism engage with the front and rear edges at the same time.
Different types of front and rear locking mechanisms are known. Some front locking mechanisms include a cam that is connected to a handle such that when the handle is put into the locked position, the cam is pushed against a surface on the front edge of the table saw to secure the rip fence in position. U.S. Pat. No. 4,846,036 to Metzger, Jr., et al., reveals a handle that moves a spring-biased clamping portion. In the locked position, the clamping portion is biased against a vertical wall in a slot that is proximate the front edge surface of the upper surface. In the released position, the handle overcomes the biased clamping portion so that it is released from the wall thereby allowing the rip fence to move along the upper surface. As the rip fence moves along the upper surface, the clamping portion moves through the slot.
Other rip fences are provided with different mechanisms to move smoothly along the upper surface. As described, slots can be provided along the upper surface of the table saw through which a portion of the rip fence, like a clamping portion, can slide. In addition, tubular rails can be provided on the front and rear sides of the table saw. In those embodiments, the rip fence include a portion that surrounds the tubular rail so that the rip fence can slide into a selected position. Other types of rails can be provided underneath the upper surface. In addition, the rip fence can include hook portions, tabs or other mechanisms that move relative a part of the upper surface or the frame so that the handle can lock the rip fence in a location.
Because of the rip fences' designs, the handles used to lock the rip fence create inefficiencies. Many such handles are quite long so that their rotation provides enough torque to adequately secure the rip fence in a selected position. Those handles often protrude significantly out from the front edge of the saw where the handle can get in the way of efficiently using the table saw. The large handles can also catch on clothing and other items. In order to reduce the size, other rip fences reorient the handle's location on the rip fence. Other prior art methods alter the direction that the handle rotates relative the table saw. Those alternative embodiments are not as easy to use.
SUMMARY OF THE INVENTION
In view of the foregoing, it is an object of the present invention to develop a portable saw that has a rip fence to overcome the deficiencies of the prior art. What is needed is a rip fence that moves between multiple positions on the table saw, that can be secured easily in any such position, and that does not unnecessarily increase the weight or general dimensions of the table saw. It is also desired to have a rip fence that is aligned parallel to the blade when it is locked into position. Moreover, the rip fence should reduce the dimensions of the handle so that it does not protrude significantly in front of the table saw.
The present invention relates to a table saw that includes a rip fence that is slidable relative to the table saw. The table saw used with the rip fence includes a frame portion and upper cutting surface. A blade extends through an opening in the upper surface to cut wood or other material. The upper surface supports the wood as it is pushed on the table saw and cut by the blade. Front and rear edge surfaces extend perpendicularly from the front and rear edges of the upper surface.
The rip fence of the present invention can be used with a table saw that has movable auxiliary table. The auxiliary table can move between a first position adjacent the upper surface and a variable second position separated from the upper surface according to any known methods. One such method includes rails that are secured to the front and rear edge surfaces of the auxiliary table and that slide along brackets on the rear and front edge surfaces of the upper surface.
The rip fence moves between positions relative the upper surface and can be locked in any such position such that the rip fence is parallel to the blade. This arrangement ensures that accurate cuts are made. To move relative the upper surface, the rip fence engages w
Romo Ezequiel
Svetlik Kenneth N.
Talesky Mark S.
Gardner Carton & Douglas
Rachuba M.
S-B Power Tool Company
Tran Kim Ngoc
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