Patent Application
20170087694
This application relates generally to tools for preparing an art canvas and, more particularly, to canvas stretching tools.
Some implementations relate generally to the construction of art media, specifically canvas stretched across a frame (e.g., a stretcher frame or stretcher bars). Stretcher frame construction is an independent but related initial step in the creation of this media. Stretched canvas may tend to rebound and relax over time. This can result in wrinkles appearing on the face of the canvas, which is not acceptable. A need may exist for a tool that provides a user with the mechanical advantage necessary to stretch a canvas taut enough to help prevent undesirable wrinkles from occurring over time.
Some implementations were conceived in light of the above-mentioned problems and limitations, among other things.
Some implementations can provide a tool to stretch canvas across a stretcher frame tight enough so as to help eliminate the possibility that wrinkles will appear on the face of the canvas (and the art painted or printed thereon) over time, and to achieve this with a light, handheld tool that is easy to use, and affordable. Some implementations can provide a tool to apply a uniform stretching force to canvas across any stretcher frame (e.g., 16 mm or thicker), while permitting the user to have one or both hands free to apply staples and or tacks as well as any other securing means that will secure the canvas to the back or the outside of the stretcher frame, with a minimum of effort. To achieve this, the disclosed tool can be equipped with a fulcrum, which gives the user the mechanical advantage to apply a taut stretch to the canvas. Some implementations can also provide an ability to grip and lock securely onto the canvas, thereby allowing one hand operation. This allows the user to engage the other hand, and sometimes both hands, to apply the staples that will hold the canvas in place in the taut position.
Some implementations can include an improvement over what may be known as “locking pliers” such as those designed to grasp and bend metal along a straight line. Some implementations can include a wide “locking jaw” feature of these conventional locking pliers. However, some implementations can add a number of improvements and modifications to conventional locking pliers to make them especially useful for stretching canvas. Specifically, the modifications can include a slip resistant material added to the inside face of the jaw plates to help provide a fixed grasp on the canvas, and a fulcrum (e.g., a second class fulcrum) that is used to lever against the inside of the stretcher frame and apply stretching action on the canvas. The fulcrum can give the user the mechanical advantage to apply an especially taut stretch on the canvas. In addition to the fixed fulcrum, a fulcrum that may be spring loaded to allow for a precise and repeatable level of tension on the canvas is described.
Some implementations can include a unique fulcrum point, and a canvas grasping improvement, consisting of a slip resistant surface, that may either be etched into the jaws or consist of a self adhesive slip resistant material on the inside faces of the jaw plates. There are several slip resistant, grasping materials that are suitable for this use with the described tool. One particularly suitable material that has proven to work well is 3M 1 Inch Safety-Walk Medium Duty Resilient Tread. This non-slip grasping technology has a very low production cost, and is very effective at grasping the canvas that is to be stretched.
The use of an improvement in locking pliers, sometimes used in metalworking arts, may substantially reduce the production cost of an implementation. The design of the canvas stretcher tool described herein is an improvement to conventional locking pliers that may consist of modifications to the existing production tooling and fabricating processes in order to mass produce the device improvements described herein. This translates to lower tooling and production costs, lower cost to the end consumer, and perhaps increased U.S. exports to other countries, because the market for this device is world-wide, thereby affording more utility to the described matter.
There is another design feature that may make the present disclosure superior to conventional systems. Conventional systems may be missing a feature that makes it necessary to occasionally adjust the pressure applied to the locking jaws. This is a particular annoyance for the user. Some implementations include a lock nut on the jaw pressure adjustment bolt. This allows the user to set the grabbing pressure of the jaw plates, and lock that pressure setting into place by tightening the nut. In so doing, users may not need to re-adjust the grabbing pressure of the jaws for sustained periods of time, if ever.
Some implementations can include low production cost, light weight, and ease of use. Light weight means less user strain and user fatigue, especially in the hands and forearms, when stretching several canvases in succession. The small size and light weight of some implementations also means lower shipping and distribution cost, and ultimately, lower cost to the consumer.
Some implementations help the user apply the canvas (or any other suitable fabric) to the stretcher frame in a uniform and taut manner, thereby completing the construction of the art media. It can be difficult to stretch the canvas taut enough to resist wrinkling without using a canvas stretching tool such as the tool described herein.
FIB. 15 shows a close up of the Obround Hole 204 for the Set Screw bolt to allow for adjustment of the location of the fulcrum. As well we show a close up of the grooves 201.
An objective and purpose of the canvas stretcher tool is to stretch the canvas 13 across a stretcher frame 12 tight enough so as to help reduce or eliminate the possibility that wrinkles will appear on the face of the canvas 13 (and the art painted thereon) over time, and to do so with a handheld tool that is easy to use and affordable. Some implementations provide the user with an ability to apply a uniform taut stretch to canvas 13 across stretcher frames 12 that are about 16 mm or thicker, while allowing the user to have at least “one hand free” to apply staples, tacks, or any other securing means, that will secure the canvas 13 to the back or the outside of the stretcher frame 12, with a minimum of effort. To achieve this, the device is equipped with locking jaw plates 4, 5 and a fulcrum 1. The locking jaw plates 4, 5 grasp the canvas 13 firmly and the fulcrum 1 is used to lever against the inside of the stretcher frame 12, to apply a taut stretch to the canvas 13. The locking jaw plates 4, 5 allow one hand operation, and this in turn allows the user to engage the other hand to apply the staples that will hold the canvas in place in the taut position.
Some implementations can include a wide “locking pliers” technology commonly found in tools that are designed to grasp and bend metal along a straight line. Some implementations can include a wide “locking jaw” feature of these metalworking tools. Some implementations add some modifications and novel improvements to these metal working “locking pliers” to make them especially useful for stretching canvas 13. Specifically, those modifications include a slip resistant material 11 added to the inside face of the jaw plates 4, 5 to assure a fixed grasp on the canvas, and a fulcrum 1 used to lever against the inside of the stretcher frame 12 to apply stretching action on the canvas 13.
Some implementations include a fulcrum point 1, and a canvas 13 grasping technology, consisting of a slip resistant material 11 on the inside face of the upper and lower jaw plates 4,5. There are several grasping surfaces that are suitable for this use on the present invention. One particularly suitable gripping surface is proven to work well is the 3M 1 Inch Safety-Walk Medium Duty Resilient Tread. This self adhesive, slip resistant grasping technology has a very low production cost, and is very effective at grasping the canvas 13 that is to be stretched.
The use of an improvement to locking pliers belonging to the locking metal working plier class of tools should substantially reduce the production cost of the canvas stretching tools described herein. The design is similar to conventional locking pliers, and very few modifications to the existing production tooling and fabrication processes will be needed to mass-produce the improvements in the disclosed device. This translates to lower tooling and production costs, lower cost to the end consumer, and perhaps increased U.S. exports to other countries, as the market for this device may be worldwide.
There is another design feature of the disclosed subject matter that makes it superior to other conventional locking pliers and canvas stretching systems that may poke holes in the canvas subjecting it to tearing. Conventional canvas stretching pliers may be missing a feature that permits a user to occasionally adjust the pressure applied to the locking jaws. This is a particular annoyance for the user. Some implementations can include a lock nut 7 on the jaw pressure adjustment bolt 6. This allows the user to set the grabbing pressure of the jaws, and lock that pressure setting into place by tightening the lock nut 7. In so doing, users may not need to re-adjust the grabbing pressure of the jaws for sustained periods of lime, if ever.
The disclosed canvas stretching tool gains merit over conventional systems by it's low production cost, its light weight, and ease of use. Having light weight means can provide less strain and less user fatigue, especially in the hands and forearms of the user, when stretching several canvases in succession. Its smaller size and weight also reduces transportation and distribution costs.
Some implementations can include modifications to existing unrelated art, namely the art belonging to the multitude of manufacturers of, such as metal working flat jaw locking pliers. Described below is one example canvas stretching tool where we will with a focus on two design features of the embodiment of the pliers: 1) the wide jaws, most of which are typically about 75 mm to 80 mm wide; and, 2) the locking pressure feature. That being said, some plier's designs are better suited than others to be adapted for use as canvas stretchers.
Regardless of the pliers manufacturer and the specific design of the pliers, in some implementations, locking pliers of the described improvement have a fulcrum 1 disposed on the outside face of the lower jaw plate 5 in order to be used as canvas stretchers. While the fulcrum may be fixed it is another improvement of the device to have a fulcrum that is biased with a spring to afford a uniform and controllable stretching force to the canvas. Such a fulcrum, either fixed or with a spring bias gives the user the mechanical advantage to apply an adequate stretch to the canvas 13. The fulcrum may also be adjustable in some implementations. For example, the fulcrum may be attached to the jaw plate via an adjustable mechanism such as a track, rail or groove that the fulcrum can move along (e.g., to give a variable distance between the fulcrum and the front edge of the jaw plate) and a securing member such as a set screw, bolt or other member that can be tightened to secure the adjustable fulcrum at a desired position on the outside surface of the lower jaw plate in order to perform a stretching operation. The set screw or other securing member may then be loosened to permit the fulcrum to be moved to a different position on the jaw plate to permit a second, different stretching operation to be performed.
There are other improvements that may be included in the device, but the number of modifications necessary to adapt these designs to canvas 13 stretching may or may not be dependent on the hardness and or the rigidity of the material in the upper and lower jaw plates 4,5.
Many of the manufacturers of these metal bending tools use a low to medium grade of carbon steel in the jaw plates 4, 5. This is suitable material for the purposes for which these metal bending tools were designed. However, the applicant has found that the lower grade alloys of this class may distort, and eventually fatigue over time, the result of which is jaw plates 4, 5 that fail to grasp evenly across the full width of the plate. This is not acceptable. However, this doesn't necessarily mean that these tools can't be used to construct a good canvas 13 stretching tool. Other disclosed features address this condition, such as to flatten the angle at which the upper and lower jaw plates 4,5 meet, and to treat the mating surfaces with a material similar or equal to self adhesive slip resistant material 11. These adaptations allow such a device to grasp and hold the canvas 13 adequately. While we describe metal alloys for use in making canvas stretching tools as described herein, other materials can be used such as a suitable carbon fiber material with associated gripping geometry that will afford the necessary grip along with required rigidity.
It is well known that, a few of these metal working tool manufacturers use high grade carbon steel throughout the construction of their tool, including the materials going into the upper and lower jaw plates 4,5. The applicant has found that these tools are especially well suited as canvas stretcher tools because the jaw plates 4,5 do not distort, and grasp the Canvas 13 evenly and adequately across the full width of the jaw. These tools are especially good candidates for canvas stretching because the only modification necessary is the addition of a fulcrum 1 on the outside surface of the lower jaw plate 5 and the application of the self adhesive slip resistant material to the inside faces of the jaw plates 4,5. Although a particular manufacturer may use high carbon steel in their jaw plates, it may be necessary to flatten the angle at which the upper and lower jaw plates 4,5 meet so as to improve the grasping power of the jaw plates 4,5 and eliminate any canvas 13 slippage that might take place. The need for this improvement depends on the hardness of the jaw plates 4, 5, which can vary substantially, and the amount of plate distortion that takes place when the tool is adjusted to a high range of pressure.
The following is a description of some implementations of the disclosed subject matter, and variations thereof. The discussion of variations should not be construed as limiting the present invention to any of those variations.
The preferred width of the jaw plates 4, 5 at the grasping face is about 75 mm to 80 mm. This dimension is well-suited for most artwork applications as well as ideal for certain upholstery stretching tasks. This width also happens to be the nominal width of most metal bending locking pliers. Jaw plate 4, 5 widths as narrow as about 30 mm to 45 mm are also practical for stretching in close proximity to the stretcher frame corners. Jaw widths greater than about 80 mm may be appropriate depending on the mechanical properties of the jaw plate material. Jaw plate material of high carbon steel material might allow a jaw width of about 100 mm or more while other alloys as well as carbon fiber materials may be more appropriate and afford an even lighter tool.
The noses (the leading edges) of the upper and lower jaw plates 4, 5 on the preferred and all alternative embodiments may be blunt or chamfered at about a 30 to 40-degree angle, or have a similar radius. This angle or radius could vary substantially. This feature makes it easy for the user to snug the canvas 13 against the back side of the stretcher frame 12 just before applying the staples, tacks or other securing means that secure the canvas 13.
The back corners of the upper and lower jaw plates 4, 5 can be trimmed at about a 30 degree to 40 degree angle to conserve weight and materials, as shown in
One preferred slip resistant material 11 for treatment of the grasping face of the upper and lower jaw plates 4, 5 is 3M 1 Inch Safety-Walk Medium Duty Resilient Tread (or equivalent or similar material) as shown in multiple figures. There may be several other materials that are just as suitable as well as appropriate geometry etched or molded into the jaw faces in either plastic, metal, or carbon fiber versions. This slip resistant material 11 is most effective when it spans the full width of both jaw plates 4, 5 no matter the width of the jaw plate.
The preferred angle at which the upper and lower jaw plates 4, 5 meet one another may vary from zero to ten degrees depending on the mechanical properties of the jaw plate material. An angle within these limits assures sufficient contact between the slip resistant material 11 and the canvas 13.
One preferred width of the fulcrum 1 is approximately 30 percent to 50 percent of the width of the upper and lower jaw plates 4, 5.
One preferred height of the fulcrum 1 may be from about 12 mm to 20 mm.
One preferred position of the fulcrum 1 may be from about 10 mm to 16 mm back from the nose (the leading edge) on the outside surface of the lower jaw plate 5, and nearly perpendicular, or within about +/−30 degrees of perpendicular, to the outside surface of the lower jaw plate 5, and nearly centered on the width of the lower jaw plate 5. See
It is, therefore, apparent that there is provided, in accordance with the various example implementations disclosed herein, canvas stretcher tools.
While the disclosed subject matter has been described in conjunction with a number of implementations, it is evident that many alternatives, modifications and variations would be or are apparent to those of ordinary skill in the applicable arts. Accordingly, Applicant intends to embrace all such alternatives, modifications, equivalents and variations that are within the spirit and scope of the disclosed subject matter.
This application claims the benefit of U.S. Provisional Application No. 62/202,266, entitled “The Grabber Handheld Canvas Stretching Tool” and filed on Aug. 7, 2015, which is incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 62202266 | Aug 2015 | US |
