This invention relates generally to the field of woodworking and more particularly to a miter bar assembly for use within a slot on a woodworking table.
High quality woodworking with safe operation requires the ability to maintain very close tolerances. Woodworking power tools such as table saws are known to include a straight groove or slot, known as a miter slot for slidably receiving a miter bar. Miter slot shapes include, but are not limited to, T-shapes and a U-shapes, referring in both instances to a cross-sectional shape of the miter slot. The miter bar moves within the miter slot to guide a work piece through a cutting tool, such as a saw blade, in a precise linear direction parallel to a desired cut line. Any gap between the width of the miter bar and the width of the slot allows for some undesirable horizontal and angular movement of the miter bar and the guided work piece as it is moved through the cutting tool.
The width of a miter slot has a nominal dimension, for example 750 mils on many table saws, but that dimension may vary by as much as 2-10 mils for any given table due to manufacturing tolerances. Such variation can create an unacceptable amount of positional uncertainty during woodworking operations. There is an ongoing effort in the woodworking industry to develop miter bars that can accommodate such variations in the slot width in order to minimize any gap between the width of the miter bar and the width of the slot.
The invention is explained in the following description in view of the drawings that show:
In response to the continued need in the woodworking industry for maintaining tight tolerances, and in particular for ensuring a snug, uniform fit of a miter bar within a woodworking table miter slot, the present inventor developed an innovative miter bar that provides a high degree of functionality in a rugged, shop-worthy device. The present inventor has since developed innovative improvements and changes to the miter bar as disclosed herein.
The miter bar assembly 10 includes a top member 12 disposed on a bottom member 14 when assembled. Each of the top member 12 and bottom member 14 has an elongated, generally rectangular, flat shape such that when joined together form a miter bar assembly 10 that will fit within a miter slot of a woodworking table. As can best be appreciated in
After the top and bottom members 12, 14 are joined together, at least one and preferably a plurality of fasteners, such as width-adjustment screws 34 shown in
As can be seen in
As best seen in
Moreover, when the width-adjusted miter bar assembly 10 is secured to the panel 38 by the attachment screws 40, the attachment screws 40 act like a clamp 56 that clamps the top member 12 between the bottom member 14 and the panel 38. This fixes the top member 12, the bottom member 14, and the panel 38 into a rigid/non-adjustable assembly. As such, even if the width-adjustment screws 34 were accessible and could be loosened, the width of the miter bar assembly 10 could not be adjusted. The only possible way to adjust the width of the miter bar assembly 10 requires also loosening the attachment screws 40 because this would permit relative movement between the top member 12 and the bottom member 14. In most cases, width adjustment requires removing the miter bar assembly 10 from the panel 38 so the miter bar assembly 10 can be accessed and adjusted as shown in
The miter bar assembly 100 is structurally and functionally similar to the miter bar assembly 10 of
Unlike the embodiment of the miter bar assembly 10 of
When the top member openings 110 are slots, the orientation and length of the path 132 is determined by the orientation and length of the slots. In the example embodiment shown, the slot is oriented at an acute angle 136 to the longitudinal extent “L” of the miter bar assembly 100, so the path 132 is likewise disposed at an acute angle to the longitudinal extent “L” of the miter bar assembly 100. When the top member openings 110 are oversized holes, the bottom member 104 is free to move within the footprint defined by the oversized holes.
This arrangement is made possible first by installing the top member fasteners 124 through a panel top member fastener hole 134 and into top member fastener features 140 (e.g., female threads) disposed in the top member 102 (as opposed to being disposed in the bottom member 104). Relief slots 142 in the bottom member 104 are present merely to accommodate any portion of the top member fasteners 124 that may pass entirely though the top member fastener features 140 (e.g., a tip thereof) and thereby protrude into the bottom member 104.
Further, access is provided to the bottom member fasteners 122 through the panel 200 via panel bottom member fastener holes 144. When the miter bar assembly 100 is secured to under the panel 200 and in a miter slot, the width of the miter bar assembly 100 can be adjusted by loosening the bottom member fasteners 122 and moving the bottom member fastener 122 within the top member openings 110. Since the bottom member fastener 122 is secured to the bottom member 104, moving the bottom member fastener 122 moves the bottom member 104, which adjusts the width of the miter bar assembly 100.
The miter bar assembly 100 thereby need not be removed in order to adjust a width thereof. This reconfiguration is more than a simple relocation of elements. Instead, this relocation yields a substantial benefit that is not expected to accompany such a relocation. As such, this relocation represents a significant improvement.
In the example embodiment shown, where the top member openings 110 are angled slots, both the angled slot and the wedge shapes 106m, 106f collective guide the movement of the bottom member 104. However, when the top member openings 110 are angled slots, the wedge shapes 106m, 106f need not be present. Similarly, when the wedge shapes 106m, 106f are present, the top member openings 110 may simply be holes that are sufficiently oversized that they permit lateral adjustment while still retaining enough structure to enable the bottom member fasteners 122 to fix the bottom member 104 in place relative to the top member 102.
In the example embodiment shown, the panel top member fastener hole 134 span one or more top member openings 110. This necessitates the panel bottom member fastener holes 144 to permit access to the bottom member fasteners 122. In the example embodiment shown, the top member 102 includes a forward half and a rearward half. This is unlike any known prior art miter bar assemblies having a right angle guide, (e.g., U.S. Pat. No. 5,402,581), which may be pivotally mounted to the miter bar arm. In those prior art miter bar assemblies, any fasteners that permit adjustment of the width of the miter bar assembly are simple disposed remote from the right angle guide as opposed to being disposed under the right angle guide.
In the example embodiment shown, a first top member fastener feature 140a is disposed in the forward half 150 of the top member 102 and a second top member fastener feature 140b is disposed in the second half 152 of the top member 102. Here again, this is unlike any known prior art miter bar assemblies having a right angle guide because the right angle guides must be disposed at and limited to one end of the miter bar assembly to function as intended.
In this example embodiment of the miter bar assembly 800, magnets are used to urge the top member 802 to move laterally relative to the bottom member 804. This, in turn, automatically adjusts a width of the miter bar assembly 800 to a width of the miter slot.
The miter bar assembly 800 includes top member openings 810 and bottom member fasteners 812 accessible through the panel bottom member fastener holes 814. The top member openings 810 are configured to permit the bottom member fasteners 812 to move therewithin while the top member 802 and the bottom member 804 to move at least laterally (e.g., perpendicular to the longitudinal extent L of the miter bar assembly 800) relative to each other. The top member openings 810 are also configured to permit the bottom member fasteners 812 to selectively secure the bottom member 804 to the top member 802 via cooperation with the bottom member fastener features 816 (e.g., female threads). The top member opening 810 may be slots or oversized holes similar to those discussed above. Slots may be oriented perpendicular to the longitudinal extent L of the miter bar assembly 800. The panel 900 includes panel top member fastener holes 820. The top member fasteners 822 cooperate with top member fastener features 824 (e.g., female threads) to fix the top member 802 to the panel 900.
In this example embodiment, top member magnets 830 are disposed in optional top member magnet receptacles 832 in the top member 802 on a first lateral side 834 of the miter bar assembly 800. Bottom member magnets 840 are secured in optional bottom member magnet receptacles 842 on a second lateral side 844 of the miter bar assembly 800. As indicated by pole markers “N” and “S”, the top member magnets 830 and the bottom member magnets 840 are oriented so that the magnetic fields repel each other and thereby create a magnetic force that urges the top member 802 laterally apart from the bottom member 804. A top member guide 850 (e.g., female) and a bottom member guide 852 (e.g., male) cooperate in a sliding relationship to ensure that the magnetic force is converted to relative lateral movement between the top member 802 and the bottom member 804.
In this example embodiment, where the top member openings 810 are slots that are oriented perpendicular to the longitudinal extent L of the miter bar assembly 800, and where the top member guide 850 and a bottom member guide 852 are present, both mechanisms ensure the magnetic force causes perpendicular lateral relative movement. However, such redundancy is not necessary. In some example embodiments, when a guiding slot is present the guide members need not be present and vice versa.
As can be seen in
The miter bar assembly 800 is installed in a miter slot simply by laterally pushing the bottom member 804 toward the top member 802 to narrow the width of the miter bar assembly 800 enough so that the miter bar assembly 800 will fit within the miter slot. This can be accomplished while the top member 802 is secured to the panel 900 by inserting a tool 870 through the panel bottom member fastener holes 814 and using the tool 870 to laterally push on the bottom member fasteners 812 in direction 872. The bottom member fasteners 812 are secured to and, in turn, thereby laterally push the bottom member 804. The miter bar assembly 800 is then installed in the miter slot and the bottom member 804 is released. Releasing the bottom member 804 allows the bottom member 804 to move laterally away from the top member 802 by virtue of the magnetic force. The miter bar assembly 800 will naturally self-expand to fill the miter slot and thereby set its proper width. The bottom member fasteners 812 can then be tightened using the tool 872 and the miter bar assembly 800 and attached panel 900 can be used for woodworking.
The relative positions of the adjacent top member magnets 830 and bottom member magnets 840 and an angle 864 of the resulting force vector can vary. For example, a pair of adjacent top member magnets 830 and bottom member magnets 840 can be positioned so that the resulting force vector is perpendicular to the longitudinal extent L of the miter bar assembly 800. Such a configuration would work with the slots and/or the top member guide 850 and the bottom member guide 852 shown. The angle 864 may be obtuse as is shown. Alternately, the angle 864 may be acute and the angle 864 may even be zero. In the latter, angled slots like those shown in the example embodiment of
In alternate example embodiments, there may be less interaction or no interaction between the top member magnets 830 and the bottom member magnets 840. Such example embodiments may be suitable for use in miter slots formed in worktables with magnetically responsive materials, such as ferritic materials et al. In such example embodiments, once the miter bar assembly is disposed in the miter slot, the top member magnets will be attracted to a first side of the miter slot and will thereby pull the top member toward the first side of the miter slot. The bottom member magnets will be attracted to a second, opposite side of the miter slot and will thereby pull the bottom member toward the second side of the miter slot. Hence, the magnets will urge the top member and the bottom member apart.
In the example embodiment shown in
The present inventors have thereby created an improved miter bar assembly that is inexpensive to implement and which provides a significantly improves the woodworking process. As such, it represents and improvement in the art.
All features disclosed in the specification, including the claims, abstract, and drawings, and all the steps in any method or process disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. Each feature disclosed in the specification, including the claims, abstract, and drawings, can be replaced by alternative features serving the same, equivalent, or similar purpose, unless expressly stated otherwise.
While various embodiments of the present invention have been shown and described herein, it will be obvious that such embodiments are provided by way of example only. Numerous variations, changes and substitutions may be made without departing from the invention herein. Accordingly, it is intended that the invention be limited only by the spirit and scope of the appended claims.
Number | Name | Date | Kind |
---|---|---|---|
228410 | Squintani | Jun 1880 | A |
503726 | Pryibil | Aug 1893 | A |
1272659 | Groomes | Jul 1918 | A |
2164615 | Mafera | Jul 1939 | A |
2524961 | Cramer, Jr. | Oct 1950 | A |
2710633 | Oberg | Jun 1955 | A |
2759503 | Goldschmidt | Aug 1956 | A |
3171632 | Jines | Mar 1965 | A |
3735206 | Pesek | May 1973 | A |
4354770 | Block | Oct 1982 | A |
4971570 | Tolle et al. | Nov 1990 | A |
5038486 | Ducate, Sr. | Aug 1991 | A |
5097601 | Pollak et al. | Mar 1992 | A |
5207007 | Cucinotta et al. | May 1993 | A |
5220485 | Chakrabarti | Jun 1993 | A |
5275074 | Taylor et al. | Jan 1994 | A |
5379669 | Roedig | Jan 1995 | A |
5382175 | Kunkel | Jan 1995 | A |
5402581 | Hurd et al. | Apr 1995 | A |
5472353 | Hristake et al. | Dec 1995 | A |
5617909 | Duginske | Apr 1997 | A |
5735054 | Cole | Apr 1998 | A |
5941514 | Burcaw | Aug 1999 | A |
6182371 | Newman | Feb 2001 | B1 |
6195905 | Cole | Mar 2001 | B1 |
6237457 | Taylor | May 2001 | B1 |
6502492 | Krohmer | Jan 2003 | B1 |
6532679 | Cole | Mar 2003 | B2 |
6672190 | Taylor | Jan 2004 | B2 |
6691423 | Fontaine | Feb 2004 | B2 |
6776076 | Salazar | Aug 2004 | B2 |
7245199 | Reilly | Jul 2007 | B1 |
7505251 | Canfield et al. | Mar 2009 | B2 |
7997313 | Wang | Aug 2011 | B2 |
8096219 | Potter | Jan 2012 | B2 |
8661954 | Quayle | Mar 2014 | B1 |
20080148582 | Watanabe | Jun 2008 | A1 |
20180036905 | Frolov | Feb 2018 | A1 |