The present specification relates to fences for table saws. More specifically, this specification relates to fences that are easy to use and ergonomical.
A table saw is a power tool used to cut a work piece to a desired size or shape. A table saw includes a work surface or table and a circular blade extending up through the table. A person uses a table saw by placing a work piece on the table and feeding it into contact with the spinning blade to cut the work piece to a desired size. The table saw is one of the most basic machines used in woodworking.
Often a person using a table saw moves a work piece into contact with the spinning blade by sliding the work piece along a guide called a fence. The fence mounts to the top of the table saw and provides a fixed reference surface relative to the blade against and along which the work piece can slide. The fence helps keep the work piece moving in a straight path without shifting or rotating. The fence can be positioned at various positions relative to the blade so that a work piece can be cut to different dimensions.
Fence 12 is positioned on or over the top surface of table 14 and the fence extends from the front to the rear of the table. Table saw 10 includes a front rail 26 positioned along the front of the saw just below the top of table 14, and fence 12 includes a head portion 24 that extends down to the front rail 26. The fence head 24 may be locked to the front rail 26 to hold the fence securely in place or unlocked to allow the fence to slide along the front rail and table. The fence may be positioned on either side of the blade.
At the end of the tube opposite the fence head there is a roller 32 with a rubber insert 34 that fits in a groove along the circumference of the roller 32 and which is secured to the end of the tube 28 by a pin 36 which passes through the center of the roller and is supported at one end in a cylindrical cavity in a roller block 40 and at the other end in a cylindrical cavity in an endcap 44. Endcap 44 is attached to the end of the tube 28 by four screws 46, one located generally at each corner of the endcap, the top two of which thread into holes near the top of the end of the tube and the bottom two pass through holes in roller block 40 and then thread into holes near the bottom of the end of the tube. Roller 32 sits within a large cylindrical shaped cavity in roller block 40 that is open at the bottom to allow the bottom of the roller to extend down below the bottom of tube 28 and roll along a rear rail 52 of the saw to support the distal end of the fence. A user may slide the fence toward or away from the blade on the table to place the fence in a desired position, and roller 32 facilitates the movement of the fence by rolling along the top of the rear rail and by supporting the distal end of the fence. The roller may be positioned to roll along the top of the table instead of along the top of the rear rail, in which case the roller may be larger or a second roller added so that the fence can roll over any slots in the table, such as a slot for a miter gauge.
The end of the fence near the front of the saw may be called a head unit or fence head, as previously mentioned. In the depicted embodiment, fence head 24 is generally shaped like a “T” when looking down at it from above, with the longer middle section of the “T” running along tube 28 and the shorter cross or arms of the “T” running along the front rail 26 of the saw, as shown in
Fence head 24 attaches to the bottom of tube 28 by two screws 54. Those screws pass through lock washers 56 and then through holes in the bottom of the tube 28 and then thread into holes in the bottom of the fence head.
The components of the fence head 24 and how they fit together are shown in
On the right side of the front cover 60, as seen in
In the depicted embodiment, on the left side of the front cover, there is a slot 120 shaped like a rectangle with the short sides rounded, located on the top of the cover running diagonally such that it moves closer to the front of the front cover while moving inwards towards the middle of the front cover. A slider block 122, that has a rectangular shape looking down from above and a stair-step shape when looking from the side, with the step running along a diagonal line as seen from above, is positioned such that the lower part of the step fits under the internal structure 70 and the upper part sits on top of the internal structure. Internal structure 70 has a diagonal running slot 124, best seen in
The screw 138 allows for adjustment of the fence head with respect to the front rail 26, and thus allows for the adjustment of the fence tube 28 with respect to the table 14 and the blade 18. As the screw is rotated slightly, the slider block is pulled to the left or moved to the right depending on which way the screw is rotated. The surface along the rear of the ledge 126 abuts an edge of the front rail on the saw, and since the screw is at a diagonal, the slider moves along a diagonal as screw 138 turns so that ledge 126 moves closer to or farther away from the front rail on the saw. That causes a slight turning or twisting of the fence in relation to the front rail, which thereby allows the fence to be adjusted so that plates 30 are parallel to the plane of the blade and so that tube 28 is parallel to the miter slots 142 in the table of the saw. When the fence is properly aligned by turning screw 138, the position of slider block 122 can be locked in place by tightening screw 128.
The bottom of slider block 122 contacts the top of front rail 26 to support the fence on the rail. In the depicted embodiment, front rail 26 includes a channel 27 extending along the top of the front rail, and the bottom of slider block 122 fits in the channel. Slider block 122 can be made of plastic to facilitate the fence sliding on the front rail. Slider block 122 also includes a front edge 123 that abuts an edge of channel 27 when the fence is clamped on the front rail. Edge 123 and the corresponding edge of channel 27 can be angled slightly to inhibit the fence from moving up when the fence is clamped to the rail.
A support 100 for the fence is located on the bottom of the right side of the fence head. Support 100 contacts the top of front rail 26, and together with slider block 122, helps support the fence on the rail. Support 100 is shaped to fit within channel 27 on the front rail, and like the slider block, can be made of plastic to facilitate the fence sliding on the rail. Support 100 includes a front edge 102 that abuts the same edge of channel 27 as front edge 123 on slider block 122. Front edge 102 on support 100 can also be angled to correspond to the angle of the edge of channel 27 to inhibit the fence from moving up when the fence is clamped to the rail, similar to front edge 123 on slider block 122. Support 100 is secured to internal head structure 70 by a screw 103 that passes through a hole in support 100 and then threads into hole 104 in internal structure 70.
Internal structure or frame 70 is shown isolated in
Underneath the locking lever 74 there is a triangular shaped linkage 160 with two extensions 162 off each corner at the base with holes 164 through each extension. There are also two extensions 166 off the corner opposite the base that also have holes 168 through them. A pin 170 (shown in
In the depicted embodiment, a short pin 176 runs through one of the holes 168 in one of the extensions 166, then through a hole 180 in each of two flat links 182 that are situated side by side and positioned between extensions 166 on the triangular linkage 160, and then through the other hole 168 in the other triangular linkage extension 166. Each link 182 is a flat metal piece curved gently along one long side until it turns roughly perpendicularly upward at one end. Holes 180 are located in each link 182 approximately at the corner between the gently curved portion and the portion that turns upward, as shown in
Locking block 200 extends up along the outside of the flat linkages 180, as shown in
Clamp or locking mechanism 150 enables the fence to be securely clamped or locked to the front rail when the locking lever is in a horizontal position as shown in
In use, fence 12 is placed on a saw, over the tabletop, with tube 28 extending from the front of the saw to the rear. The fence is supported at the front by slider block 122 and support 100 resting on front rail 26, and at the back by roller 32 and rubber insert 34 resting on rear rail 52. When the fence is placed on the saw, clamp or locking mechanism 150 is open, as shown in
A user then grasps the fence by hand adjacent locking lever 74, and slides the fence to the right or left until it is located at a desired position relative to blade 18. Grasping the fence over the locking lever is between the ends of the fence and near the center of gravity of the fence because the head portion has more mass than the fence tube, and as a result, grasping the fence over the locking lever reduces the tendency of the fence to twist or rotate when a user slides the fence into position. In other fences, a user grasps a handle extending out from the proximate end of the fence (i.e., the end nearest the front of the saw), and when the user applies a force to the handle to slide the fence into position, the distal end of the fence (i.e., the end furthest from the front of the saw) lags behind resulting is a jittering or rough motion rather than a smooth translational motion.
With locking mechanism 150 open, the proximate end of locking lever 74 (i.e., the end nearest the front of the saw) extends up above the top surface of tube 28, as shown generally in
To unclamp or unlock the fence, a user simply presses or pushes down with a finger on the distal end of locking lever 74 (i.e., the end furthest from the front of the saw). Pushing down on the distal end of locking lever 74 moves the bottom of locking block 200 away from the front rail, as explained, to open the clamp. The locking mechanism is also stable in this open position because holes 168 move over-center. Accordingly, locking mechanism 150 may be thought of as being bi-stable, i.e., stable in both an open and closed position and configured so that the locking mechanism goes to either an open or closed position.
Spring 212 is configured to bias the locking mechanism open, so when the distal end of locking lever 74 pivots down enough to move holes 168 over-center, i.e., above the line between holes 164 and 192 (as seen in
A locking mechanism as described herein can also be configured so that it automatically locks or clamps the fence to the saw when a user is not touching the locking lever. This may be thought of as an auto-lock feature because the fence automatically locks in place when a user releases or moves their hand away from the fence. Additionally, a locking mechanism can be configured to open when a user pivots a locking lever a first distance, and to close automatically when the user releases the locking lever, but the locking mechanism will stay open if the user pivots the locking lever a second distance greater than the first distance. With this configuration, a user can selectively open the locking mechanism and know that the fence will lock in place when the user removes their hand from the fence, or the user can open the locking mechanism and have it remain open when the user removes their hand from the fence. This latter situation would be useful if, for example, the user wanted to remove the fence from the saw.
The fences described herein are ergonomic and easy to use. A user can position the fence on the saw and then lock the fence in position without having to reposition their hand on the fence and without having to grasp a separate handle. In the depicted embodiment, this is due at least in part to the fact that the locking lever is positioned substantially or wholly between the ends of the elongate portion of the fence, and/or substantially above the saw table, and/or within the perimeter of the table (where the perimeter includes any rail or rails attached to the table), and/or at a location where it is natural to grasp the fence.
Providing a fence with a locking lever as described herein also promotes usability of the fence because the locking lever does not extend substantially above the top of tube 28 when the locking mechanism is closed or clamped, as seen generally in
Providing a fence with a locking lever at least partially above the table decreases the perimeter of the saw and therefore increases the clearance, maneuverability, storability and usability of the saw. With the locking lever positioned at least partially above the table, the need to watch out for a handle sticking out from the front of the saw when moving or storing the saw is eliminated, thereby making it is easier to move the saw through doorways and other tight places, and making it is easier to store the saw or place the saw in the back of a truck. The fence handle simply does not stick out from the saw, and therefore, the saw is easier to move around. Additionally, a user can stand closer to the front edge of the table saw because there is no fence handle to block the user from doing so, and standing closer to the front edge of the table saw makes it easier to control the movement of the work piece past the blade.
With a fence as described herein, the perpendicularity of the fence relative to the front of the table saw, and the parallelism between the face plates on the fence and the blade, are easy to adjust, as explained. Moving slider block 122 to the right or left adjusts the perpendicularity of the fence and aligns face plates 30 with the blade. After slider block 122 is moved, it may be necessary to adjust the position of locking block 200 to insure the locking block provides an appropriate or desired clamping pressure on the front rail. This is accomplished by turning screw 202, as explained. Front cover 60 includes a hole 302, shown in
The fences described herein are applicable to woodworking power tool equipment, and particularly to table saws.
It is believed that the disclosure set forth above encompasses multiple distinct inventions with independent utility. While each of these inventions has been disclosed in its preferred form, the specific embodiments thereof as disclosed and illustrated herein are not to be considered in a limiting sense as numerous variations are possible. The subject matter of the inventions includes all novel and non-obvious combinations and sub-combinations of the various elements, features, functions and/or properties disclosed herein. No single feature, function, element or property of the disclosed embodiments is essential to all of the disclosed inventions. Similarly, the recitation of “a” or “a first” element, or the equivalent thereof, should be understood to include incorporation of one or more such elements, neither requiring nor excluding two or more such elements.
It is believed that the following claims particularly point out certain combinations and sub-combinations that are directed to disclosed inventions. Inventions embodied in other combinations and sub-combinations of features, functions, elements and/or properties may be claimed through amendment of the present claims or presentation of new claims in this or a related application. Such amended or new claims, whether they are directed to a different invention or directed to the same invention, whether different, broader, narrower or equal in scope to the original claims, are also regarded as included within the subject matter of the inventions of the present disclosure.
This application claims the benefit of and priority from U.S. Provisional Patent Application Ser. No. 61/892,237, filed Oct. 17, 2013, which is incorporated herein by reference.
Number | Date | Country | |
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61892237 | Oct 2013 | US |