BACKGROUND OF THE INVENTION

This invention relates generally to the field of saws and, more particularly, to a spiked tip device for attachment to a portable power chain saw or the like for improving its operation and safety.

It is well known that portable power chain saws create a sub¬ stantial risk of injury to the user, especially if improperly or carelessly used. The hazards relate primarily to the exposed nature of the chain moving along the guide bar. The fact that chain saws are basically hand tools whose control is often left to the strength and skill of the operator makes them especially dangerous. This is particularly so when it is considered that the very purpose of chain saws often relegate their use to less than ideal environments, such as wooded areas where dense and damp underbrush with rugged terrain and other inclement conditions often prevent the operator from obtaining the necessary leverage to exert sufficient control over the saw.

One of the most dangerous aspects of chain saw operation involves what is known as "kickback". Kickback is an inherent phe¬ nomenon in chain saws which produces an uncontrolled rapid movement of the saw. Kickback may occur when contact with another object is made by the moving chain as the chain travels around the nose of the guide bar. When kickback occurs, the saw may violently kick back from the object being cut and possibly result in severe injury to the operator.

Another potential danger associated with chain saws is the vibration emitted therefrom during operation. It has been reported that vibration from hand-held tools such as chain saws can contribute

to a condition known as Raynaud's Syndrome. Symptoms of Raynaud's Syndrome may include tingling, numbness and blanching of the fingers.

There have been many attempts in the prior art to improve the safety of chain saws, including some intended to prevent the conditions of kickback from occurring or minimizing the effects of kickback. These attempts sometimes involved the addition of various guards and automatic braking devices to the saw. For example, U.S. Patent No. 4,193,193 to Holzworth discloses a guard which extends from the motor housing along the top of the guide bar above the chain and down over the nose of the saw. While the guard may prevent inadvertent con¬ tact with the moving chain along the top of the guide bar, such a guard, however, precludes use of the vitally needed upper cutting surface of the saw.

Braking devices also have severe limitations in that they do not prevent kickback from occuring and do not significantly halt the motion of the chain after kickback has occurred. Thus, the operator may still be violently struck and seriously injured with the sharp chain eve if the brake engages in time. Brakes are also relatively expensive and can cause damage to the saw. Further, it is difficult and impractical for the effectiveness of braking devices to be mea¬ sured by an operator who is relying on such a device to prevent injury in the event of kickback.

Other efforts to provide a safer chain saw have included various redesigns of the saw chain and guide bar. These measures also have significant practical drawbacks in that they result in a saw that is often less efficient and less capable of performing the tasks for which it is needed. Improvements made in the saw chain, for example, are often diminished by use of the saw or defeated by filing of the chain.

Although safety devices customarily add weight and expense to the saw, and often result in some loss of utility, the ideal safety device for a chain saw should have the following characteristics. The device should:

1. make the saw safer to operate;

2. not result in significant loss of utility of the saw;

3. not significantly increase the weight of the saw;

4. not significantly increase the expense of the saw;

5. add new utility to the saw to offset any added weight, expense or loss of old utility (thereby discouraging removal);

6. make the saw easier to operate with less operator fatigue; and

7. the beneficial features of the safety device should not be diminished by use of the saw or defeated by opera¬ tor action.

While chain saw safety devices known in the prior art meet some of the above characteristics, they remain deficient in most areas.

Even with the various safety devices known in the prior art, chain saws are still extremely dangerous to operate due to the problems associated with the operator not having full control over the saw at all times. The difficulty in maintaining control is primarily related to the unsecured tip of the saw. While the operator may be able to maintain fairly good control over the motor end of the saw, where the handles are located, complete control is not possible without means for directly controlling the saw tip. This is especially important in situations where the danger of kickback is present. Therefore, in order to efficiently maximize control over a chain saw, means must be provided for stabilizing the saw tip with the objective being to satisfy the aforementioned characteristics that the ideal safety device should have. SUMMARY OF THE INVENTION

It is therefore the overall object of the present invention to provide a tip stabilizing device for attachment to a portable power chain saw which improves the safety, utility and operation of the saw, while also resulting in greater productivity of the operator.

A specific object of this invention is to provide a tip stabilizing device for attachment to a chain saw which prevents the conditions for kickback from occurring and which will motivate chain saw opera¬ tors to more frequently use anti-kickback devices known in the prior art.

Another specific object of this invention is to provide a tip sta¬ bilizing device for attachment to a chain saw which makes the saw more stable and easier to control without a significant loss of utility of the saw, while maximizing the cutting performance of the combined bar and chain saw attachment.

A further specific object of this invention is to provide a tip stabilizing device for attachment to a chain saw which is lightweight, inexpensive and readily attachable and removable from the saw.

A still further specific object of this invention is to provide a tip stabilizing device for attachment to a chain saw which substantially reduces harmful vibrations that may be transmitted from the saw to the operator and reduces operator fatigue.

A further specific object of this invention is to provide a tip stabilizing device for attachment to a chain saw which results in longer life of the cutting chain and which protects the chain and guide bar from damage due to contact with foreign objects at the nose of the guide bar.

Another specific object of the invention is to provide a tip sta¬ bilizing device for attachment to a chain saw which utilizes the chain and wood interactive forces to improve the operation of the device and which can lead to improvements in the design of the guide bar, chain and chain saw (e.g., such as the addition of supporting handles and/or controls in various configurations to further improve utility, safety and operation when the saw tip is stabilized).

It is another specific objective of the present invention to provide a tip stabilizing device for attachment to a chain saw which can be used in conjunction with anti-kickback devices known in the

prior art and which makes the saw more stable and easier to control without significant loss of utility of the saw.

The stabilizing device disclosed in the present application com¬ prises a plate having a hub or mounting feature ^' and a plurality of spikes. The hub is used for readily mounting the device near the end of the chain saw guide bar. In one embodiment of the device, the spikes extend forward of the guide bar and may be used to anchor the saw tip to the ground, an adjacent log or other supporting surface. In other embodiments, the spikes are reversed in order to engage the object being cut for stabilizing the saw tip. In all embodiments, spikes may be added which extend outwardly from the plane of the guide bar in various directions to also provide tip stability. Certain embodiments of the device also encompass any combination of these spikes.

A novel aspect of the tip stabilizing device is that the reactive forces between the wood being cut and the moving chain are used as an aid in lodging the spikes into the supporting surface. For example, when cutting on the lower guide bar section with conventional chain movement and with the spikes extending forward of the guide bar, the reactive forces tend to pull the saw from the operator causing the spikes to further engage the supporting surface. Similarly, when cutting on the upper guide bar section with the spikes reversed, the saw is pushed in the direction of the operator, thereby resulting in the spikes further engaging the object being cut. By adjusting the direction of the spikes, depending upon which cutting surface is used and the direction of chain movement, the chain saw tip can be secured in virtually every cutting situation.

The tip stabilizing device allows a complete change of force application to the operation of the saw. In a cutting process using a stabilized tip, the wood acts as a fulcrum. However, without a stabil¬ ized tip, the chain saw requires the use of two hands so as to establish a fulcrum at either or both hands. The operator of a saw

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which is stabilized at the tip is thereby provided with a mechanical advantage. Consequently, with the tip of the saw stabilized, there are resulting benefits to the operator: there is little need to activate the fulcrum at the forward handle end of the saw, thus permitting one-handed operation; the working effort on the operator is substantially reduced, not only from the decreased pressure required because of the mechanical advantage gained, but also from the more natural posture of the operator as the stabilized tip allows the motor end of the saw to be raised upward to within reaching position of the operator; and a stabilized saw tip allows the weight of the saw to be relieved from the operator as the saw rests on the stabilized tip. All of these benefits substantially reduce the normally heavy and fatiguing effort required of the operator.

An additional benefit resulting from the increased leverage made possible by a stabilized saw tip is that a dull chain may be used to cut when it would not otherwise be effective due to the limited oper¬ ator force application of a saw without a stabilized tip. This offers the advantage of not having to sharpen the saw chain as frequently, resulting in greater productivity and reduced chain replacement cost.

In addition to providing a significant increase in the stability of the saw with the resultant safety and operational benefits, the tip device disclosed in the present application serves a variety of other functions, including: serving as a chain gauge for making certain checks and measurements with respect to the chain; providing a chain catcher to prevent whipping of the chain back toward the operator should the chain break on the top section of the bar; and, serving to prevent the chain from external contact at the critical nose of the guide bar, thus preventing the conditions for kickback from occurring. Another major advantage of tip stability is that vibrations which are normally transmitted from the saw to the operator, possibly resulting in detrimental physical effects, are substantially reduced due to ground absorption and reduced hand forces applied, thus reducing vibration

transmission. A stabilized tip also permits the chain saw user to prevent the object being cut from pinching the guide bar and chain without stopping the saw. Moreover, stabilizing the tip in an upright position for starting the saw, adjusting the carburetor and sharpening the chain.

Further embodim ents of the tip stabilizing device of the present invention relate to use of a chain saw in extremely close cutting quarters where insufficient room exists for the cutting opera¬ tion to take place with the stabilizing device mounted on the guide bar. Though the stabilizing device could be removed, removal of the stabilizing device would expose the tip of the saw and subject the user to injury due to kickback. Although kickback could be prevented by mounting a known anti-kickback device on the chain saw guide bar after the stabilizing device is removed (assuming the anti-kickback device will not itself interfere with the cutting operation), this would be both inconvenient and wasteful of time. More importantly, once the stabilizing device is removed, human nature and the desire to save time may cause the chain saw user not to take the time to install an anti-kickback device to protect against the risk of injury due to kickback. This is especially true when the duration of the close- quarter cutting operation is very short. Thus, several embodiments of the present invention are directed to a tip stabilizing device for use in conjunction with a known anti-kickback device so that when it becomes necessary to remove the stabilizing device to perform a cutting operation in close quarters, the user is protected against kickback without additional action on his part. Furthermore, this tip stabilizing device can be readily and easily mounted and dismounted from the chain saw guide bar to facilitate use of the chain saw in performing cutting operations in close quarters. Thus , the inconvenience and loss of time associated with removing and mounting the stabilizing device is greatly reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a side elevational view of one embodiment of the tip stabilizing device disclosed in the present application.

Figure 2 is a front elevational view of the tip stabilizing device of Figure 1.

Figure 3 is a top elevational view of the tip stabilizing device of Figure 1.

Figure 4 is a sectional view of the tip stabilizing device of Fig¬ ure 1 along line 4-4.

Figure 5 is a perspective view of the base plate of the tip sta¬ bilizing device of Figure 1.

Figure 6 is a perspective view of the secondary plate of the tip stabilizing device of Figure 1.

Figure 7 is a side elevational view of another embodiment of the tip stabilizing device disclosed in the present application.

Figure 8 is a front elevational view of the tip stabilizing device of Figure 7.

Figure 9 is a front elevational view of the tip stabilizing device of Figure 7 showing an alternate spike arrangement.

Figure 10 is a top elevational view of the tip stabilizing device of Figure 7.

Figure 11 is a side elevational view of a further embodiment of the stabilizing device disclosed in the present application.

Figure 12 is a front elevational view of the tip stabilizing device of Figure 11.

Figure 13 is a top elevational view of the tip stabilizing device of Figure 11.

Figure 14 is a front elevational view showing the operation of the chain gauge of the various embodiments of the tip stabilizing device disclosed in the present application.

Figure 15 is a side elevational view of another embodiment of the tip stabilizing device disclosed in the present application.

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Figure 16 is a side elevational view of a further embodiment of the tip stabilizing device disclosed in the present application.

Figure 17 is a side elevational view illustrating the tip stabil¬ izing device of Figure 1 attached to a chain saw having conventional chain movement and engaging the ground while making a bucking cut.

Figures 18 and 19 are side elevational views illustrating the tip stabilizing device of Figure 1 attached to a chain saw having conventional chain movement and engaging an adjacent log while making a bucking cut.

Figure 20 is a side elevational view illustrating the tip stabil¬ izing device of Figure 7 attached to a chain saw having conventional chain movement and engaging an adjacent log while making a bucking cut.

Figures 21 and 22 are side elevational views illustrating the tip stabilizing device of Figure 11 attached to a chain saw having reverse chain movement and engaging the log being cut while making a bucking cut.

Figures 23 and 24 are side elevational views illustrating the tip stabilizing device of Figure 15 attached to a chain saw having reverse chain movement and engaging the log being cut while making a bucking cut.

Figure 25 is a side elevational view illustrating the tip stabil¬ izing device of Figure 15 attached to a chain saw having reverse chain movement and engaging an adjacent log while making an undercut.

Figure 26 is a side elevational view illustrating the tip stabil¬ izing device of Figure 15 attached to a chain saw having conventional chain movement and engaging the ground while making a bucking cut.

Figure 27 is a side elevational view illustrating the tip stabil¬ izing device of Figure 15 attached to a chain saw having conventional chain movement and engaging the log being cut while making an undercut or perhaps a felling cut.

Figure 28 is a side elevational view illustrating the tip stabil¬ izing device of Figure 15 attached to a chain saw having conventional chain movement and engaging an adjacent log while making a bucking cut.

Figure 29 is a side elevational view illustrating the tip stabil¬ izing device of Figure 1 attached to a chain saw having conventional chain movement and engaging a tree trunk with the side spike while performing a limbing operation.

Figure 30 is a side elevational view of the tip stabilizing device according to a further embodiment of the present invention.

Figure 31, 32 and 33 are sectional views of the tip stabilizing device according to the present invention as shown in Figure 30.

Figure 34 is another side elevational view of the tip stabilizing device according to the present invention shown in Figure 30.

Figure 35 is a side elevational view of the tip stabilizing device according to the present invention shown attached the chain saw guide bar in conjunction with an anti-kickback device.

Figure 36 is a sectional view of the tip stabilizing device according to the present invention as shown in Figure 35. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to Figures 1-29, the tip stabilizing device disclosed in the present application will now be discussed in detail. In the embodiment shown in Figures 1-6, the tip stabilizing device includes base plate 100 as shown in Figure 5 and secondary plate 200 as shown in Figure 6. Plates 100 and 200 are bonded together into a single unit as shown in Figures 1-4 and is attached to the forward end of the guide bar of the chain saw as described in further detail below.

With reference to Figure 5, base plate 100 includes mounting feature 119 for readily attaching and removing the tip stabilizer to the forward end of the chain saw guide bar. As shown, mounting feature 119 is comprised of mounting hole 103 for receiving a retaining bolt through a corresponding hole in the guide bar. Mounting hole 103 may

be internally threaded to engage the retaining bolt or the retaining bolt can be secured by an appropriate locking washer and nut. Mounting feature 119 also includes raised anti-rotation tab or fastener

118 and protrusions 104-107. Tab 118 is designed to engage an appro¬ priately located hole in the guide bar, thus preventing inadvertent rotation of the tip stabilizer around mounting hole 103. Protrusions 104-107 are designed to contact appropriately located rivet heads in the guide bar, thus aiding tab 118 in preventing the tip stabilizer from inadvertent rotation. Protrusions 104-107 may also be used to apply pressure through the guide bar plate against the guide bar sprocket inner race so as to prevent sprocket wheel binding. Mounting feature

119 serves here only to illustrate one way of attaching the tip stabil¬ izer to the guide bar. Any attachment device or devices may be employed which securely attaches the stabilizer to the guide bar and does not interfere with the cutting operation.

Base plate 100 also includes raised tabs 109-114. As shown in Figure 5, tabs 109-114 may be blanked from plate 100 and formed perpendicular thereto. Tabs 109-114 form a guard around the saw chain which prevents the chain from flying away from the saw should the chain break. Together with flange 203, discussed below, tabs 109-114 also provide a protective shield to prevent soil, abrasions or other foreign objects from contacting the moving chain and causing damage to the chain and guide bar. As best illustrated in Figures 1-3, tabs 109-112 further serve as a mounting flange for secondary plate 200. With reference to Figures 14A and B, the outline of tab 114 is specially formed to provide edge 114A for measuring the top plate angle of right hand chain cutter 120 and edge 114B for measuring the top plate angle of left hand chain cutter 121, both without removing either the chain or the stabilizer tip from the saw. Tab 114 also includes edge 114C whose corresponding inside edge 114D on base plate 100 (see Figure 5) may be used to measure the gullet angles of the chain.

Base plate 100 further includes elongated spikes 101, shorter spikes 102, reverse spikes 117 and outwardly projecting side spike 116. Side spike 116, like tabs 109-114, may be blanked from plate 100 at an appropriate angle. The operation of spikes 101, 102, 117 and 116 will be explained in greater detail with reference to Figures 17-19 and 29 below.

With reference to Figure 6, secondary plate 200 is comprised of elongated spikes 201, outwardly projecting side spike 202 and flange 203. Flange 203 extends the full length of the rear edge of plate 200 and is used for mounting plate 200 to plate 100. Side spike 202 may likewise be blanked from secondary plate 200 at an appropriate angle. Spikes 201 and 202 corespond to spikes 101 and 116, respectively, located on base plate 100.

Base plate 100 and secondary plate 200 are formed into a single unit by bonding flange 203 to tabs 109-112 as shown in Figures 1-4. Bonding may be by any appropriate means, including epoxy, welding or spot welding. The application of this embodiment of the device to a chain saw will now be discussed with reference to Figures 17-19 and 29.

As shown in Figures 17-19, the tip stabilizer of this embodiment is attached to the forward end of the chain saw guide bar using mounting feature 119 and an appropriate retaining device, e.g., a bolt or rivet. When attached, spikes 101, 102 and 201 extend forward of the guide bar and chain for engaging an adjacent surface. Elongated spikes 101 and 201 are especially suited for ground engagement, as shown in Figure 17, when making a bucking cut using conventional chain movement as indicated by the direction of the arrows. In this application, normal forces generated at the chain/wood interface by the momentum of the chain pulls the saw forward causing spikes 101, 201 or 102 to self -engage into the ground. The saw may then be pivoted downwardly about the anchored point to complete the cutting operation. As the saw pivots downward, the above-described normal forces keep

spikes 101, 201 or 102 in ground engagement, thus stabilizing the saw tip. Stabilizing the tip substantially increases the stability of the saw, thereby providing the operator with a much greater opportunity to maintain control over the saw.

Because the saw is resting on a stabilized tip and there are reduced handforces, the amount of vibration that is transmitted to the operator's hands and arms is reduced. It has been suggested that pro¬ longed exposure to chain saw vibration, coupled with other factors, may have adverse effects over time, often leading to the development of Raynaud's Syndrom or "white fingers." Thus, in situations where chain saws are routinely and regularly used, a means for reducing vibration is particularly advantageous. Reduced vibration also aids in operator comfort, thereby reducing fatique and allowing the operator to be productive for much longer periods of time.

Figure 18 illustrates the application of the present embodiment of the device using an adjacent log as the supporting means. The application shown in Figure 19 is similar, however, shorter spikes 102 are used to engage the adjacent log.

Side spikes 116 and 202 are used for side engagement and are particularly useful when limbing a fallen tree as shown in Figure 29. Either side spike 116 or 202 self-engage the trunk of the tree, as the saw rests on a limb extending outward of the trunk of the tree, thus allowing pivoting action.

The operation of reverse spikes 117 can be understood with reference to Figures 21, 22 and 27. While these figures show differ¬ ent embodiments of the spike tip device, they are illustrative of the operation of reverse spikes 117. Figures 21 and 22 show a chain saw making a bucking cut and having reverse chain direction as indicated by the arrows. In this application, the normal forces generated at the chain/wood interface by the momentum of the moving chain pushes the saw in the direction of the operator. Thus, with the tip stabilizer of the present embodiment (Figures 1-6) attached to the guide bar,

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reverse spikes 117 self-engage the log being cut adjacent the cutting groove as best shown in Figure 22. Figure 27 shows a chain saw making an undercut and having conventional chain direction as indicated by the arrows. In this application, normal forces at the chain/wood interface also push the saw in the direction of the operator. Thus, reverse spikes 117 likewise self -engage the log, stabilizing the saw tip.

In the embodiment of the device shown in Figures 7-10, the tip stabilizer is of single-piece construction. One piece construction results in a device that is easier and less expensive to manufacture. This embodiment of the tip stabilizer includes plate 300 with mounting feature 301 and spike flange 302. The stabilizer is attached to the forward end of the guide bar as described in further detail below.

With reference to Figure 7, mounting feature 301 includes mounting hole 308, protrusions 303-306 and raised anti-rotation tab 307. These interrelated elements are similar in purpose and function to the corresponding elements associated with mounting feature 119 as discussed with respect to the above first embodiment of the device. Flange 302 includes a series of spikes 309. Spikes 309 may be blanked from flange 302 in a variety of patterns as shown in Figures 8 and 9. When the device is attached to the guide bar, spikes 309 extend forward of the guide bar and chain for engaging a log or other supporting surface to stabilize the saw tip. Flange 302 also serves as a chain guard to prevent the chain from whipping back toward the operator should it break. Flange 302 further serves as a protective shield to prevent soil or other abrasives from contacting the moving chain and causing damage to the chain and guide bar.

Base plate 300 also includes upwardly projecting side spikes 310 and 311 and reverse spikes 312. These spikes are similar in purpose and function to side spikes 116 and 202 and reverse spikes 117 as described with respect to the above first embodiment of the device.

The application of this embodiment of the device is best illustrated by Figure 20. Figure 20 shows a chain saw making a

i jREA i

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bucking cut and having conventional chain movement as indicated by the direction of the arrows. The forces generated at the chain/wood interface by the momentum of the moving chain cause the tip stabil¬ izer to self-engage the adjacent log. The saw tip is accordingly sta¬ bilized, substantially increasing the stability of the saw and making it much easier to control.

In the embodiment of the device shown in Figures 11-13, the tip stabilizing device is also of single-piece construction. This embodiment is primarily designed for chain saws having reverse chain movement. With reference to Figure 11, base plate 400 includes mounting feature 401, reverse spikes 407, upwardly projecting tabs 402-404 and spikes 406.

Mounting feature 401 includes the same interrelated elements and serve a similar purpose and function as mounting feature 119 as described in the above first embodiment of the device.

Tabs 402-404 may be blanked from base plate 400. Tabs 402-405 serve as a chain guard as well as a protective shield to prevent soil or abrasives from coming into contact with the moving chain. Tab 402 also serves as a chute or baffle for feeding sawdust away from the operator. The outline of tab 404 is specially formed to provide a chain gauge as discussed with respect to the above first embodiment of the tip stabilizing device and shown in detail in Figure 14.

Figures 21 and 22 illustrate the application of this embodiment of the device. A chain saw is shown making a bucking cut and having reverse chain movement as indicated by the direction of the arrows. When starting a cut in the log, as shown in Figure 21, spikes 406 self-engage the log due to the action of the forces at the chain/ ood interface pushing the saw toward the operator. Once the saw has cut into the log, as shown in Figure 22, reverse spikes 407 self-engage. Thus, spikes 406 and 407 permit the saw tip to be stabil¬ ized for the duration of the cut.

This embodiment of the device may also be effectively used on a saw having conventional chain movement in undercutting situations and in felling operations.

In the embodiment of the device shown in Figure 15, the stabil¬ izing tip is of single-piece construciton and is designed for use with a chain saw having either conventional or reverse movement of the chain. It is comprised of symmetrical mounting features 501 and 502, symmetrical middle spikes 503 and 504 and symmetrical end spikes 505 and 506.

Mounting features 501 and 502 and their related elements are similar in purpose and function to mounting feature 119 in Figure 5 as described with respect to the above first embodiment of the device. Depending upon the application, the operator can select which mounting feature to use. The operation of end spikes 505 and 506 and middle spikes 503 and 504 can best be understood with reference to Figures 23-28.

Figures 23 and 24 illustrate a chain saw making a bucking cut and having reverse chain movement as indicated by the direction of the arrows. When the saw first cuts into the log, as shown in Figure

23, spikes 506 self -engage the log as a result of the normal forces generated at the chain/wood interface pushing the saw in the direction of the operator. As the saw cuts through the log, as shown in Figure

24, spikes 503 also self-engaged, further stabilizing the saw tip.

With reference to Figure 25, reverse chain movement is used to make an undercut. In this application, the normal forces at the chain/wood interface cause spike 505 to self-engage an adjacent log. Thus, stabilizing the saw tip.

In the applications of the tip stabilizing device shown in Figures 23, 24 and 25, mounting feature 501 is used to attach the stabilizer tip to the guide bar.

Figures 26-28 illustrate the application of this embodiment of the device with a saw having normal conventional chain direction. In

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these applications, mounting feature 502 is used to attach the stabilizer to the guide bar. In Figure 26, the force at the chain/wood interface causes spike 506 to self-engage the ground; in Figure 27, spikes 504 and 505 are caused to self-engage the log being cut and in Figure 28, middle spike 503 is caused to self-engage an adjacent log.

Figure 16 illustrates a similar embodiment to that of Figure 15 but includes additional spikes 507 and 508. The addition of spikes 507 and 508 permit the device to be used in any variety of cutting opera¬ tions without remounting, thus using the alternate mounting feature.

With reference to Figures 30-36, a further embodiment of the invention will be described. In this embodiment, the tip stabilizing device can be used in conjunction with a SAFE-T-TIP anti-kickback device. SAFE-T-TIP is a trademark of the Homelite Division of Textron Inc. The SAFE-T-TIP anti-kickback device is attached to the end of the chain saw guide bar and is formed with a flange which covers the chain at the nose section of the saw. Accordingly, the nose section of the guide bar is prevented from being used as a cutting surface, therefore preventing the conditions for kickback from occurring. The tip stabilizing device of this embodiment is designed to mount on the chain saw in conjunction with the SAFE-T-TIP device.

The stabilizing device of this embodiment comprises a plate having a quick release mounting feature and a plurality of spikes. The quick release mounting feature is used for readily and easily mounting and dismounting the device near the end of the chain saw guide bar in conjunction with an already installed SAFE-T-TIP anti-kickback device. Thus, an important feature of the present invention is that it may be readily mounted and detached from the chain saw guide bar in conjunction with an anti-kickback device known in the prior art . Accordingly, in those situations where close cutting quarters does not permit the stabilizing device to remain mounted on the guide bar, it can be removed, leaving the anti-kickback device in place. Thus, the operator is prevented from exposure to the dangers of kickback without additional action on his part.

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When mounted on the saw, the tip stabilizing device of the present invention stabilizes the saw tip in much the same manner as the tip stabilizing device disclosed in the present application, as described above. For example, when cutting on the lower guide bar section with conventional chain movement and with the spikes extending forward of the guide bar, the chain/ wood interface reactive forces tend to pull the saw forward from the operator, thus causing the spikes to further engage the supporting surface. Similarly, when cutting on the upper guide bar section with the spikes reversed, the saw is pushed in the direction of the operator, thereby resulting in the spikes further engaging the object being cut. By adjusting the direction of the spikes, depending upon which cutting surface is used and the direction of chain movement, the chain saw tip can be secured in virtually every cutting situation.

The tip stabilizing device allows a complete change of force application to the operation of the saw. In a cutting process using a stabilized tip, the wood acts as a fulcrum. However, without the sta¬ bilized tip, the chain saw requires the use of two hands so as to establish a fulcrum at either hand. The operator of a saw which is stabilized at the tip is thereby provided with a mechanical advantage.

Consequently, with the tip of the saw stabilized, there are resulting benefits to the operator: there is no need to activate the fulcrum at the forward end of the saw, thus permitting one-handed operation; the working effort on the operator is substantially reduced, not only from the decreased pressure required because of the mechanical advantage gained, but also from the more natural posture of the operator as the stabilized tip allows the motor end of the saw to be raised upward to within reaching position of the operator; and the tip stabilizer allows the weight of the saw to be relieved from the operator as it rests on the stabilizer. All of these benefits substantially reduces the normally heavy and fatiguing effort required of the operator.

An additional benefit resulting from the increased leverage is that a dull chain may be used to cut when it would not otherwise be effective due to the limited operator force application of a saw without a stabilized tip. This offers the advantage of not having to sharpen the saw chain as frequently, resulting in greater productivity and reduced chain replacement cost.

Another major advantage of tip stability is that vibrations which are normally transmitted from the saw to the operator, possibly result¬ ing in detrimental physical effects, are substantially reduced. Other advantages include the chain saw user being able to start the saw, adjust the carburetor of a running saw and sharpen the saw chain all from an upright position or any other tip stabilized position.

The tip stabilizing device of the present embodiment is shown in Figures 30-36, with the device shown mounted on a chain saw guide bar in Figures 35 and 36. The tip stabilizer of this embodiment is designed for use on a chain saw in conjunction with a SAFE-T-TIP anti-kickback device or nose tip guard device without modifying the device or defeating its anti-kickback feature. The mounting feature on the tip stabilizer permits the user to readily remove or install the sta¬ bilizer as required by the particular cutting operation being performed. When the stabilizer is removed, the anti-kickback device remains in place, preventing the conditions of kickback from occurring.

With reference to Figure 30, the improved tip stabilizing device of the present invention comprises plate 1 having a plurality of forwarding extending short spikes 2 and a plurality of elongated spikes 3. Spikes 2 and 3 may also be formed in a plurality of spaced paralleled rows rather than in a single row as shown. Plate 1 also includes laterally extending soil guard 4 with stiffening rib 5. Plate 1 is attached to the forward end of the chain saw guide bar via mounting feature 6. Mounting feature 6 includes hole 7 which receives the same mounting bolt used to secure the SAFE-T-TIP anti-kickback device to the guide bar. Plate 1 is prevented from rotating about the

mounting bolt by locator nib 8 and soil guard stiffening rib 5. Mounting of plate 1 on the guide bar and the operation of soil guard stiffening rib 5 and locator nib 8 will be discussed in more detail below with reference to figures 35 and 36.

When plate 1 is attached to the forward end of the chain saw guide bar, short spikes 2 and elongated spikes 3 extend beyond the forward end of the guide bar and chain away from the motor or power head end of the saw for engaging an adjacent surface. Plate 1 is also positioned on the guide bar so as not to interfere with the removal and replacement of the saw chain. Elongated spikes 3 are especially suited for ground engagement when making a bucking cut using conventional chain movement as shown in Figure 17. Although Figure 17, as well as Figures 18-29, illustrate the application of various embodiments of the tip stabilizing device disclosed in appli¬ cant's pending Application Serial No. 454,641, these figures also illustrate the application of the improved tip stabilizing device of the present invention. Accordingly, where appropriate, reference will be made to these figures to illustrate the application of the present invention.

In the application of the present invention illustrated in Figure 17, normal forces generated at the chain/wood interface by the momentum of the chain pulls the saw forward causing elongated spikes 3 to self-engage into the ground. The saw may then be pivoted downwardly about the anchored point to complete the cutting operation. As the saw pivots downward, the above-described normal forces keep the spikes in ground engagement, thus stabilizing the saw tip. Stabil¬ izing the tip substantially increases the stability of the saw, thereby providing the operator with a much greater opportunity to maintain control over the saw.

Because the saw is resting on a stabilized tip and there are reduced hand forces, the amount of vibration that is transmitted to the operator's hands and arms is reduced. It has been suggested that

prolonged exposure to chain saw vibration, coupled with other factors, may have adverse effects over time, often leading to the development of Raynaud's Syndrome or "white fingers". Thus, in situations where chain saws are routinely and regularly used, a means for reducing vibration is particularly advantageous. Reduced vibration also aids in operator comfort, thereby reducing fatigue and allowing the operator to be productive for much longer periods of time.

Figure 18 illustrates the application of the present invention using an adjacent log as the supporting means. The application shown in Figure 19 is similar, however, shorter spikes 2 are used to engage the adjacent log.

It has also been found that the improved tip stabilizing device of the present invention may also be construed with reverse spikes which extend from the tip of the guide bar toward the motor or power head end of the saw to engage a fixed surface; e.g., the reverse spikes shown in Figure 11. The operation of this embodiment of the invention can be understood with reference to Figure 21. Fig¬ ure 21 shows a chain saw making a bucking cut and having reverse chain direction as indicated by the arrows. In this application, the normal forces generated at the chain/ ood interface by the momentum of the moving chain pushes the saw in the direction of the operator. Thus, with the improved stabilizer of the present invention attached to the guide bar, the reverse spikes self-engage the log being cut adja¬ cent the cutting groove as shown in Figure 21. The reverse spikes may also be mounted in the opposite direction from that shown in Fig¬ ure 21 for use with a chain saw making an undercut or a felling cut and having conventional chain direction as indicated by the arrows. Figure 27 illustrates this application of the present invention. In this application, normal forces at the chain/wood interface also push the saw in the direction of the operator. Thus, the reverse spikes likewise self-engage the log, stabilizing the saw tip.

It has further been found that the improved tip stabilizing device of the present invention may also be construed with one or more laterally extending spikes. Such spikes are particularly useful when limbing a fallen tree as shown in Figure 29. As shown, the lat¬ erally extending spike self-engages the trunk of the tree as the saw rests on a limb extending outward of the trunk of the tree, thus allowing pivoting action.

With reference to Figure 36, mounting feature 6 comprises debossed portion 10 which permits plate 1 to be mounted on the guide bar such that short spikes 2 and elongated spikes 3 are in spaced parallel relationship with cutting chain 20. Mounting feature 6 also includes raised portion 9 through which mounting hole 7 is located. With reference again to Figure 36, raised portion 9 permits mounting bolt 21 to be received through hole 7 to fastening device 12. Debossed portion 10 permits fastening device 12 to be readily tightened and untightened to secure plate 1. Fastening device 12 can be a regular nut or can also be a hand-wing nut. Fastening device 12 may also comprise a push-button spring release mechanism or any other quick release device which provides secure assembly and ready disassembly of plate 1 from the guide bar.

With reference to Figures 35 and 36, mounting of the tip stabil¬ izing device of the present invention in conjunction with the SAFE-T-TIP anti-kickback device 30 will now be described. SAFE-T-TIP device 30 is attached to one side of the forward end of guide bar 22 in the manner known in the prior art with bolt 21. Rivet head 31 of the SAFE-T-TIP device is received in slot 32 in guide bar 22 to prevent the SAFE-T-TIP device from rotating. Mounting feature 6 of the tip stabilizer device of the present invention is attached to the side SAFE-T-TIP device 30, with hole 7 of mounting feature 6 piloting on the SAFE-T-TIP device clinch nut. SAFE-T-TIP device 30 and plate 1 are secured to guide bar 22 by fasten device 12. Locator nib 8 and stiffening rib 5 of soil guard 4 engage the

outer contour of the SAFE-T-TIP device for positively locating the device and preventing its rotation.

With reference again to the improved tip stabilizing device shown in Figures 30-36, it has been found that the length of forwardly extending elongated spikes 3 should ideally be a certain minimum length to provide proper ground engagement. It has been found that when a single row of elongated spikes 3 are used, each spike should be at least one inch in length. Where more than one row of spikes are used, each spike should be at least 3/4 of an inch in length. Moreover, it has been found that the total cross-sectional area of the spikes should also be a certain minimum value to provide proper ground engagement. It has been found that spikes having a total cross-sectional area in the range of 0.10-0.40 square inches provides proper ground engagement, with 0.20 square inches being ideal. It has further been found that the angle at which elongated spikes 3 project from plate 1 should be in the range 50°-80° downwardly and forwardly from the longitudinal axis of the guide bar. Such a range is ideally suited to provide comfortable and efficient use of the saw over its projected arc of use as shown in Figure 35.

It has been found that a stabilizing saw tip also allows con¬ trolling of saw pinching. For example, when cutting a large log, after the edge of the guide bar opposite the cutting surface clears the outer edge of the log, there is a tendency for the log to buckle and close the cutting kerf, depending on the log's resting position. When this occurs, the chain and guard can become pinched in the kerf. How¬ ever, by inserting an extended wedge in the kerf prior to the log buckling, pinching can be prevented. With the tip of the saw stabil¬ ized in accordance with the present invention, one-handed operation of the saw is possible, leaving the other hand free to install the wedge in the kerf to prevent pinching without stopping the cutting process or letting go of the saw.

In addition to the benefits mentioned above, it has been found that a stabilized saw tip provides some practical non-cutting benefits as well. For example, with the tip of the saw stabilized by jamming the tip device into the ground or an adjacent log, the operator can start the saw from a much safer upright position. Moreover, adjustments to the carburetor of a running saw can also be made from an upright position with the saw tip stabilized. These are all practical benefits which substantially enhance the safety of the saw.

A further non-cutting advantage provided by a stabilized saw tip has to do with sharpening the chain. In the prior art, the chain saw chain was sharpened with the operator bending over the saw on the ground. Maintaining such a position for an extended period of time is uncomfortable, requiring frequent periods of rest. With the tip of the saw stabilized in accordance with the present invention, the saw chain may now be sharpened in an upright position which is a more natural position for the user and is much more comfortable.

The above embodiment of the present invention describes a tip stabilizing device for attachment to a portable power chain saw which makes the saw safer and easier to operate while overcoming many of the disadvantages of chain saw attachments known in the prior art. The device may be mounted on the chain saw guide bar in conjunction with an anti-kickback device. Accordingly, when the stabilizer is removed to permit a cutting operation in close quarters, the operator is not exposed to kickback.

Obviously, many modifications and variations of the above- described preferred embodiments will become apparent to those skilled in the art from a reading of this disclosure. It should be realized that the invention is not limited to the particular apparatus disclosed, but its scope is intended to be governed only by the scope of the appended claims.

OMPI