Hammer with lightweight handle

Abstract

A hammer has a head connected to a lightweight handle with a center of gravity that is proximate to the head of the hammer and separated from the base of the handle by 85%-95% of the total hammer length, measured from the base of the handle to the top side of the head. The handle weight is between 10%-20%. Accordingly, the lighter handle allows the center of gravity of the hammer to be within 85%-95% of the total hammer length from the base of the handle while maintaining a comfortable head weight between 14 oz. and 25 oz. The hammer also has inflection point proximate to the base of the handle providing multiple gripping sections to allow a user to grip the handle in different locations and at different gripping angles that move relative to the longitudinal axis of the hammer.

Claims

1. A hammer, comprising: a head having a first longitudinal axis, a striking face perpendicular to the first longitudinal axis, a head length extending along the longitudinal axis, and a top having an end face; and a handle connected to the head at a side of the head opposite from the end face, wherein the handle comprises an internal composite layer, an external composite layer, and at least one intermediate composite layer between the internal composite layer and the external composite layer, wherein the internal composite layer is formed around an internal core, wherein the handle has a second longitudinal axis substantially perpendicular to the first longitudinal axis, a maximum lateral dimension less than the head length, and a handle length, wherein the head and the handle comprise a total hammer length extending between a base of the handle and the end face of the head, wherein the hammer has a center of gravity proximate to the end face at a location that is 85%-95% of the total hammer length measured from the base, wherein a diameter of the striking face of the head is less than 1.5 times the maximum lateral dimension of the handle, and wherein the internal composite layer and the external composite layer extend the handle length along the second longitudinal axis, wherein the intermediate layer is proximate to the head and extends a length towards the base, and wherein the length is shorter than the handle length.

2. The hammer of claim 1, wherein a total hammer weight of the head and the handle is between 0.5 kg and 1.5 kg, and wherein a handle weight is between 10%-20% of the total hammer weight.

3. The hammer of claim 1, wherein the handle weight is between 0.075 kg and 0.15 kg, and wherein the total hammer length is between 13 inches and 20 inches.

4. The hammer of claim 1, wherein a front side of the handle is comprised of a concave outer surface proximate to the base of the handle and an inflection point at an end of the concave outer surface, wherein the inflection point is located a distance away from the base of the handle, and wherein the distance is less than 5 times the diameter of the striking face.

5. The hammer of claim 1, wherein the handle is further comprised of a protective plug located at the base of the handle, wherein the internal core is further comprised of a reinforcing block and at least one of a hollow core and a foam core, wherein the reinforcing block is positioned at a mounting end of the handle opposite the base, wherein at least a portion of the mounting end is held within the head substantially perpendicular to the end face, and wherein at least one of the hollow core and the foam core extend from the reinforcing block to the protective plug at the base of the handle.

6. The hammer of claim 1, wherein the head is connected to the handle at the side of the head opposite from the end face by a fastener, wherein the fastener is selected from the group consisting of a set screw, a wedge fit, a wedge fastener, a star nut, a clamp fit, an adhesive and any combination thereof, and wherein the striking face is further comprised of a hard substrate, a malleable striking surface, and an embedded grit, wherein the malleable striking surface is wad of deformable material bonded to the hard substrate, and wherein the embedded grit is formed by a plurality of particles distributed throughout the wad of deformable material.

7. The hammer of claim 1, wherein the head is further comprised of a nail-pull, wherein the nail-pull is comprised of a first notch in a first sidewall of the head and a second notch in a second sidewall of the head, wherein the first notch and second notch are aligned to each other and are offset from a backside of the handle, wherein the first notch engages a head of the nail in a first position, wherein the second notch engages the head of the nail and the first notch engages a shank of the nail in a second position.

8. A hammer, comprising: a head having a first longitudinal axis, a striking face perpendicular to the first longitudinal axis, a head length extending along the longitudinal axis, and a top having an end face; and a handle connected to the head at a side of the head opposite from the end face, wherein the handle comprises an internal composite layer, an external composite layer, and at least one intermediate composite layer between the internal composite layer and the external composite layer, wherein the handle has a second longitudinal axis substantially perpendicular to the first longitudinal axis, a maximum lateral dimension less than the head length, and a handle length, wherein the head and the handle comprise a total hammer length extending between a base of the handle and the end face of the head and comprise a total hammer weight, wherein a handle weight is between 10%-20% of the total hammer weight, wherein a diameter of the striking face of the head is less than 1.5 times the maximum lateral dimension of the handle, wherein the internal composite layer is formed around an internal core, wherein the internal composite layer and the external composite layer extend the handle length along the second longitudinal axis, wherein the intermediate layer is proximate to the head and extends a length towards the base, and wherein the length is shorter than the handle length.

9. The hammer of claim 8, wherein the hammer has a center of gravity proximate to the end face at a location that is within 85%-95% of the total hammer length.

10. The hammer of claim 8, wherein the total hammer weight is between 0.5 kg and 1.5 kg, wherein the total hammer length is between 13 inches and 20 inches, and wherein the handle weight is between 0.075 kg and 0.15 kg.

11. The hammer of claim 8, wherein a front side of the handle is comprised of a concave outer surface proximate to the base of the handle and an inflection point at an end of the concave outer surface, wherein the inflection point is located a distance away from the base of the handle, and wherein the distance is less than 5 times the diameter of the striking face.

12. The hammer of claim 11, wherein the head is connected to the handle at the side of the head opposite from the end face by a fastener, wherein the fastener is selected from the group consisting of a set screw, a wedge fit, a wedge fastener, a star nut, a clamp fit, an adhesive and any combination thereof, and wherein the striking face is comprised of a hard substrate, a malleable striking surface, and an embedded grit, wherein the malleable striking surface is wad of deformable material bonded to the hard substrate, and wherein the embedded grit is formed by a plurality of particles distributed throughout the wad of deformable material.

13. The hammer of claim 11, wherein the head is further comprised of a magnet insert, and wherein the magnet insert is affixed to a side of the head.

14. The hammer of claim 8, wherein the handle is further comprised of a protective plug located at the base of the handle, wherein the internal core is comprised of a reinforcing block and at least one of a hollow core and a foam core, wherein the reinforcing block is positioned at a mounting end of the handle opposite the base, wherein at least a portion of the mounting end is held within the head substantially perpendicular to the end face, and wherein at least one of the hollow core and the foam core extend from the reinforcing block to the protective plug at the base of the handle.

15. A hammer, comprising: a head having a first longitudinal axis, a striking face perpendicular to the first longitudinal axis, a head length extending along a longitudinal axis, and a top having an end face, wherein the striking face is further comprised of a hard substrate, a malleable striking surface, and an embedded grit within the malleable striking surface, and wherein the malleable striking surface is bonded to and is deformable relative to the hard substrate; and a handle connected to the head at a side of the head opposite from the end face, wherein the handle has a second longitudinal axis substantially perpendicular to the first longitudinal axis, a maximum lateral dimension less than the head length, and a handle length, wherein the head and the handle comprise a total hammer length extending between a base of the handle and the end face of the head, wherein a diameter of the striking face of the head is less than 1.5 times the maximum lateral dimension of the handle, wherein a front side of the handle is comprised of a concave outer surface proximate to the base of the handle and an inflection point at an end of the concave outer surface, wherein the inflection point is located a distance away from the base of the handle, and wherein the distance is less than 5 times the diameter of the striking face.

16. The hammer of claim 15, wherein the hammer has a center of gravity proximate to the end face at a location that is within 85%-95% of the total hammer length, wherein the total hammer length is between 13 inches and 20 inches, and wherein a total hammer weight is between 0.5 kg and 1.5 kg.

17. The hammer of claim 15, wherein the total hammer length is between 13 inches and 20 inches, wherein a total hammer weight is between 0.5 kg and 1.5 kg, and wherein the handle weight is between 0.075 kg and 0.15 kg, and wherein the distance of the inflection point away from the base is less than 4 times the diameter of the striking face.

18. The hammer of claim 15, wherein the handle weight is between 10%-20% of the total hammer weight, and wherein the handle is made from at least one of a composite material, a metal material, a plastic material, and a wood material.

19. The hammer of claim 15, wherein the handle comprises an internal composite layer, an external composite layer, and at least one intermediate composite layer between the internal composite layer and the external composite layer, wherein the internal composite layer is formed around an internal core, and wherein the internal composite layer and the external composite layer extend the handle length along the second longitudinal axis, wherein the intermediate layer is proximate to the head and extends a length towards the base, and wherein the length is shorter than the handle length.

20. The hammer of claim 15, wherein the malleable striking surface is a wad of material welded onto the hard substrate, wherein the embedded grit is comprised of particles distributed throughout the wad of material, and wherein the malleable striking surface further comprises a mushroom shape.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention will become more fully understood from the detailed description and the accompanying drawings. The drawings constitute a part of this specification and include exemplary embodiments of the invention, which may be embodied in various forms. It is to be understood that in some instances, various aspects of the invention may be shown exaggerated or enlarged to facilitate an understanding of the invention; therefore the drawings are not necessarily to scale. In addition, in the embodiments depicted herein, like reference numerals in the various drawings refer to identical or near identical structural elements.

(2) FIGS. 1A-1C illustrate three types of prior art hammers having center gravity closer to the handle base than the present invention.

(3) FIG. 2A is a side view of a hammer according to the present invention with a lightweight handle and a center of gravity proximate to the head.

(4) FIGS. 2B and 2C are perspective views of the inventive hammer in FIG. 2A.

(5) FIG. 3A is a side view of the inventive hammer with a range of GC locations.

(6) FIG. 3B is a detail view of the hammer handle shown in FIG. 3A with a schematic overlay view of a change in curvature chart for the handle shape.

(7) FIG. 4A shows the power gripping section of the inventive hammer.

(8) FIG. 4B shows the precision gripping section of the inventive hammer.

(9) FIG. 4C shows the straight gripping section of the inventive hammer.

(10) FIG. 5A is an exploded schematic view of the layers forming the handle.

(11) FIGS. 5B and 5C are illustrative views of the force applied to the inventive hammer at impact.

(12) FIGS. 6A and 6B are cross-sectional views of the inventive hammer with the lightweight handle having a reinforcing block and a foam core.

(13) FIGS. 6C and 6D are cross-sectional views of the inventive hammer with the lightweight handle having the reinforcing block and a hollow core.

(14) FIGS. 7A-7H show cross-sectional views of alternative heads for the hammer.

(15) FIG. 8A is a perspective view of the head of the inventive hammer.

(16) FIGS. 8B and 8C are perspective views of the head with a magnet insert.

(17) FIG. 9A-9D are perspective views of the double-nail pull of a hammer with lightweight handle.

(18) FIGS. 10A and 10B are perspective views of a malleable striking face.

(19) FIGS. 10C and 10D are cross-sectional views of the malleable striking face.

(20) FIG. 11A is a perspective view of a spring striking face.

(21) FIG. 11B-11D are cross-sectional views of the spring striking face.

(22) FIG. 12A is a sequential view of a prior art hammer swung and striking a nail.

(23) FIG. 12B is sequential view of the inventive hammer swung and striking a nail.

(24) FIGS. 13A and 13B are graphs plotting the center of gravity and comparing the inventive hammer with prior art hammers.

(25) FIGS. 14A and 14B are graphs plotting the handle weight relative to the total hammer weight and comparing the inventive hammer with prior art hammers.

(26) FIGS. 15A and 15B are graphs plotting the ratio of the handle weight to head weight and comparing the inventive hammer with prior art hammers.

(27) FIGS. 16A and 16B are graphs plotting the apparent handle weight relative to the total hammer weight and comparing the inventive hammer with prior art hammers.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(28) The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.

(29) As illustrated in FIGS. 2A-2C, a hammer 10 has a head 12 that is connected to a handle 14. The handle may be grasped and swung by a user to drive a nail 80, stake or similar fastener and is lightweight, preferably being made from a strong and lightweight composite material like polymer reinforced composite fiber, carbon fiber, fiberglass, Kevlar, and aramid weaves. The hammer head 12 has a striking face 16 used for striking the fastener 80, a claw end 86 opposite the striking face and a head length 44 separating the claw and striking face. The handle is attached to the head at a position opposite the end face 48 and extends away from the head's end face 46a to a handle base 56. The head's longitudinal axis 42 extends between the circular striking face and the end of the hammer's claw and is substantially perpendicular to the handle's longitudinal axis 50 extending between the base of the handle and the end face of the head. The handle has a mounting end 74 opposite from the base, and in the preferred embodiment the mounting end is at least partially disposed within the head of the hammer. The mounting end may be secured to the head by a variety of fasteners 36 that may include but is not limited to a set screw 36a, wedge fit 36b, a wedge fastener 36c, star nut 36d, clamp fit 36e, epoxy or other adhesives 36f or a combination thereof, such as shown in FIGS. 6 and 7.

(30) The head 12 is connected to the handle 14 at a side opposite the end face 48 through the head void 94 and in the preferred embodiment houses at least a portion of the handles mounting end 74a as shown in FIG. 6. The striking face has a preferred diameter 60 of 1.5 inches (1.5 in.3.81 cm) but may vary so long as the diameter is less than 1.5 times the maximum lateral dimension 52 of the handle. The head length 44 extends from the striking face to the opposite end of the head which may include a claw portion 86. The handle's longitudinal axis is substantially parallel to the plane of the striking face. The head and handle combine to produce a total hammer length 20 between a base of the handle and the end face of the head that is between thirteen inches (13 in.33 cm) and twenty inches (20 in.51 cm).

(31) An aspect of the hammer 10 invention is a center of gravity (CG) 18 that is proximate to the end face 46a of the head 12. The CG is located away from the base 56 of the handle 14 by a distance that is 85%-95% of the total hammer length 20 (L.sub.Tot), measured between the base of the handle and the end face of the head. Because the CG is proximate to the head, the majority of the weight of the hammer is targeted to the striking face 16 which promotes easier use and better striking. The inventive hammer's CG is closer to the head than previously considered by or possible in the prior art, and by positioning the hammer's CG even closer to the head and further away from the base of the handle, the inventive hammer reduces the amount of shock delivered down the entire handle, ultimately reducing the chance of injury to the user.

(32) As shown in FIG. 12b, placing the CG very nearly behind the striking face causes the majority of the swing force to be transmitted to the nail, and very little swing force remains in the handle which is much lighter than the head, reducing the counteracting force that the hand 130a must apply to the handle when the nail is impacted at 130b. Conversely, as seen in FIG. 12A, in prior art hammers, the handles are heavier than in the present invention and the hammer CG is located further away from the head so when the head strikes the nail, there is more energy in the movement of the handle that must be counteracted by the person's hand. Accordingly, in the prior art hammers, the counteracting force that the hand 132a must apply to the handle when the nail is impacted at 132b is significantly greater than the force 130a required when the nail is impacted 130b by the hammers according to the present invention. The different levels of counteracting force are shown in the drawings with different sized arrows, and it will be appreciated that without the increased force applied by the hand of the user with the prior art handles, the distance in which the handle would continue to rotate around the nail would be greater than with the hammers of the present invention, and this is also shown in the drawings, Additionally, when the head strikes the nail, the nail serves as a fulcrum so the closer that the CG is to the user's hand and further away from the fulcrum nail, the less mechanical advantage there is to the lever arm between the user's hand and the CG. Accordingly, in the present invention, shifting the location of the CG towards the head increases the lever arm, thereby increasing the mechanical advantage of the handle and further decreasing the force required to stop the handle. In comparison, in the prior art hammers, the hammer's CG is further from head which decreases the lever arm, thereby decreasing the mechanical advantage of the handle and further increasing the force that is necessary to stop the heavier prior art handles. Generally, more energy is delivered to the hand and more shock must be absorbed with the prior art hammers with heavier handles and CG locations further from the head as compared with the present invention. It is the force on the user's hand at impact that causes injury. Therefore, by reducing the weight of the handle and shifting the center of gravity towards the head, the present invention reduces the shock felt by the user through the handle as compared to prior art hammers.

(33) Another aspect of the present invention is a handle weight (Wt.sub.Ha) that is less than 20% of total hammer weight (Wt.sub.Tot), preferably between 10%-20%. Because the weight of the handle is lighter relative to the entire weight of the hammer, the center of gravity 18 is closer to the head 12. Conversely, traditional hammers have handle weights that makeup greater than 25% of total hammer weight. These heavier handles contribute to greater shock and prevent the center of gravity of the hammer from being located as close to the head as in the present invention while maintaining a comfortable head weight (Wt.sub.Hd) between fourteen (14 oz.396 g) and twenty-five ounces (25 oz.708 g). Examples of prior art hammers and their centers of gravity can be seen in FIGS. 1A, 1B and 1C. Additionally, as the mounting end 74 of the handle is contained within a void in the head 94, at least of a portion of the handle contributes to the head weight.

(34) In the present invention, the effective weight of the handle is further reduced where the heaviest part of the handle is held within the head when mounted. Accordingly, the center of gravity 18 of the entire hammer 10 is moved closer to the head 12. The lightweight handle is made from layers of composite material 26, including the internal layer or layers 26a, that preferably extend the entire length of the handle, the external layer or layers 26b that also extend the entire length of the handle, with reinforcing in intermediate layers 26c in areas that experience high stress when the hammer is swung and impacted. Additionally, these composite layers are formed around a non-structural internal core 32 that is preferably made of foam 32a. However, the core itself does not provide any strength or structural support once the composite is hardened, thus the internal core 32 may be hollow 32b or made from some other non-structural material. Conversely, internal cores described in the prior art are designed to provide structural support, such as the support-bearing core disclosed in U.S. Pat. No. 5,211,669. In the present handle, the internal core is not a support-bearing core, providing insufficient tensile strength or impact strength to serve as a hammer handle without the composite layers surrounding the core. Accordingly, in the handle of the present invention, the handle support is produced by the multiple composite layers and not by the core. Accordingly, the handle 14 is designed to maximize strength and stiffness while reducing mass. The carbon fiber and Kevlar layers, and possibly alternative layers such as fiberglass, are the only structural components and are designed to provide adequate strength during use so that other materials such as aluminum, metal, plastic, titanium or wood are not needed.

(35) Another aspect of the present invention is an inflection point 24 in the handle 14 proximate to the base 56 of the handle to provide multiple gripping sections 96. In effect, the inflection point 24 allows a user to grip the handle in different locations and at different gripping angles 98 that rotate relative to the longitudinal axis 50 of the hammer as shown in FIG. 4. The inflection point 24 is a relatively short distance (d.sub.IP) from the base of the handle 56, the distance being less than five (5) times the diameter (D.sub.SF) of the striking face 60, preferably less than four (4) times the diameter (d.sub.IP<4D.sub.SF). Accordingly, the multiple gripping sections 96 and axes 98 are proximate to the base of the handle. With the innovative curvature and inflection point of the present invention, if the user wants to change gripping angles for a particular application, the user can still grip the handle close to the base 56 and does not need to grip the handle at a position significantly closer to the head 12 as would be necessary with prior art handles which sacrifice leverage. Accordingly, the inflection point 24 provides a curved power section 96a for framers with a power gripping axes 98a between 10-20 behind the longitudinal axis 50 of the handle, a 96b neutral gripping section having neutral axes 98b substantially parallel with the longitudinal axis 50 of the handle, and a precision gripping section 96c for finishing work with a precision gripping axes 98c between 5-10 in front of the longitudinal axis 50 of the handle. These gripping sections 96 are proximate to the base of the handle which provides better swinging leverage as compared to the prior art. Further, as shown in FIG. 4, the user's knuckles are in relatively the same position but by holding the handle in different places, the orientation of the hammer changes relative to the gripping hand.

(36) In addition to the light weight handle, the head 12 includes a number of inventive features. The preferred head uses a welded box construction with a head void 94 and has replaceable striking faces 16 that attach to a set screw 36a which also holds the handle 14 onto the head 12 as described below in the preferred embodiment. Both the handle and striking face can be easily replaced in the field with common tools and a variety of striking faces can be attached to the hammer head for different building applications. For example, a textured face can be used for framing and heavy construction, a smooth face can be used for lighter, finish carpentry, while a plastic face can be used for non-marring or non-sparking applications. Additionally, the head has a traditional rip claw 86 for pulling nails and prying boards, but also features a double nail-pull 38 with two notches 76a, 76b on opposite sidewalls 78 for high-leverage nail pulling.

(37) As generally explained above, in the present invention, the hammer's CG 18 is very close to the end face 46a of the head 12 and may actually be within the head section. In particular, the CG is located away from the base of the handle 56 by approximately 85%-95% of the total hammer length 20. To shift the CG closer to the head 12, it is an aspect of the present invention to have a hammer handle 14 significantly lighter than the prior art such that the handle itself is between 10%-20% of the total hammer weight. Additionally, the ratio between the head weight and handle weight of the present invention is greater than the highest ratio found in the prior art. Table I below and FIGS. 13-15 document weight, length and CG measurements for the hammer 10 according to the present invention as compared with prior art hammers.

(38) TABLE-US-00001 TABLE I Hammer Measurements CG Location Total Head Handle Hammer as % of Hammer Brand/ Weight Weight Weight Length Hammer Handle Material (g) (g) (g) (cm) Length Tool Driven Framer 616 529 (M) 87 43.50 87.9% (hollow core)/ Carbon Fiber/Kevlar Tool Driven Builder 710 620 (M) 90 44.45 88.9% (hollow core)/ Carbon Fiber/Kevlar Tool Driven Framer 640 529 (M) 111 43.50 88.1% (foam core)/ Carbon Fiber/Kevlar Tool Driven Builder 735 620 (M) 115 44.45 89.1% (foam core)/ Carbon Fiber/Kevlar Stiletto Ti-bone/ 894 425 (A) 469 43.66 67.3% Titanium Stiletto 14P/ 783 397 (A) 386 40.64 70.7% Polycarbonate Estwing 22S/ 945 519 (M) 426 40.32 73.2% Steel Estwing Big Blue/ 1089 708 (A) 381 45.40 74.1% Steel DeWalt 15 Old/ 863 425 (A) 438 41.91 69.5% Steel - I-Beam DeWalt 15 New/ 838 397 (M) 441 41.91 68.2% Steel Stamped DeWalt 17 S/ 830 481 (A) 349 45.09 80.3% Hickory Straight DeWalt 17 C/ 844 624 (M) 220 42.86 81.5% Hickory - Curved DeWalt 20/ 798 400 (A*) 398 35.24 69.4% Steel Powerstrike Curved/ 795 454 (A) 341 43.97 80.1% Aluminum Powerstrike Straight 773 454 (A) 319 45.09 79.6% W/Aluminum + Wrap Powerstrike Straight/ 805 454 (A) 351 45.09 78.2% Aluminum Vaughan 23/ 928 652 (A) 276 44.45 81.8% Hickory Husky 21/ 950 595 (A) 355 45.72 79.2% Hickory Vaughan 21/ 929 608 (M) 321 40.64 76.2% Fiberglass Hart 21/ 1100 711 (M) 389 45.72 76.4% Fiberglass

(39) For the data in Table I above, the total weight of the hammers were measured on a single scale and are displayed in grams. In regards to the head weight, some of the prior art hammers did not have removable heads and were made of materials that did not easily facilitate the removal the head of the hammer from the handle. Accordingly, the head weights are followed by an A indicating that manufacturer's advertised head weight was used. For example, the Husky 21 hickory handle has an advertised head weight of twenty-one ounces (21 oz.595 g), as indicated in Table I above. Conversely, heads easily separable from the handle were individually weighed and indicated in Table I with an M. Additionally, the A* indicates the DeWalt 20 steel hammer having an advertised head weight of twenty ounces (20 oz.567 g) but an estimated head weight of fourteen ounces (14 oz.400 g). This estimate is based on DeWalt's advertised claim that this hammer is an Optimal Weight Distribution hammer which is defined in Black & Decker's U.S. Pat. No. 8,534,643 as a weight distribution spread almost equally between the head and the handle of the hammer. Accordingly, the estimated head weight of 400 grams gives a weight distribution between the head weight and handle weight of approximately 1:1, matching the optimal weight distribution as advertised and indicated with A*. Subsequently, the handle weight was calculated by subtracting the head weight from the total weight and the hammer length was measured from the top face of the head to the base of the handle in centimeters. Lastly, the location of the CG for each hammer was determined and is reflected in Table I as a percentage of the entire length measured from the base of the handle.

(40) As illustrated in FIGS. 13A and 13B, embodiments of the present invention have a CG location that is greater than 85% of the total hammer length away from the base of the handle, preferably between 85% and 95%. The CG location for the present invention is plotted with the data for the prior art hammers relative to both the total length of the hammer, illustrated in FIG. 13A, and the total weight of the hammer, illustrated in FIG. 13B. As evident from Table I above and the charts in FIGS. 13A and 13B, the hammer CGs for prior art hammers are mostly located at 75%5% of the total hammer length, and the location of the hammer CG for the prior art hammers is less than 82% of the total hammer length. FIGS. 1A, 1B, and 1C show the approximate 70%-75% location 18d as well as the approximate 82% location 18e.

(41) To have a center of gravity proximate to the head, the weight of the handle is reduced to 10%-20% of the total weight of the hammer. Accordingly, the head weighs substantially more than the handle, and the CG consequently is shifted closer to the head and further away from the handle base. Hammers of the type documented in Table I have a total weight under 1.5 kg, with most being between 0.75 kg and 1.0 kg, with the present invention having a total hammer weight under 0.75 kg due to the lightweight handle. According to the present invention, the handle weight may vary between 0.075 kg and 0.15 kg depending on the length of the handle and the types of materials that are used. In comparison, the handles of the prior art hammers are all over 0.2 kg, with most handles weighing between 0.3 kg and 0.5 kg. Accordingly, the handle of the present invention is not only substantially lighter than the prior art handles, it contributes a smaller percentage to the overall weight of the hammer and ultimately results in an overall lighter hammer with the same head weight as the prior art hammers.

(42) As explained above and shown in FIG. 3A, the hammer's CG 18b according to the present invention is located more than 85% of the hammer's total length from the handle end to the head. This CG location 18b corresponds to more than 90% of the handle's length, and is preferably greater than 95% of the handle length 18a. The CG location can even be beyond the end of the handle length (>100%), such as when the hammer's CG is actually within the head section of the hammer 18c. The handle length is defined as the distance between the extreme end of the handle at the gripping end and a plane perpendicular to the longitudinal axis of the handle that is tangent to the circumference of the striking face at its nearest point to the gripping end.

(43) As documented in Table II below, the handle weight of the present invention is below 20% of the total weight of the handle. This relative weight of the handle to the total weight of the hammer is plotted relative to the total length of the hammer in FIG. 14A and the total weight of the hammer in FIG. 14B. The low handle weight percentage is maintained while also having a total hammer length and weight that is comparable to the prior art and preferably between 35 and 47 centimeters and 600 and 1200 grams as documented in Table I and respectively shown in FIGS. 14A and 14B. Accordingly, it is another aspect of the present invention to have a handle weight that is between 10%-20% of the total weight of the entire hammer. In the preferred embodiment, the handle weight is between 12%-18% of the total weight but this preferred embodiment is not intended to be limiting as the weight of the handle will vary depending on the hammer length and types of materials used to construct the handle.

(44) While the total weight of the inventive hammer is comparable to the prior art hammer weights, inasmuch as they are all significantly less than the weight of sledgehammers and are typically more than a specialty lightweight tacking hammers, the lightweight handle of the present invention clearly results in a hammer with a weight that heretofore has not been achieved or even considered. According to the present invention, the total hammer weight is lighter than the prior art hammers by a measure that is equal to the differential in the weights of the handles as shown in Table I and illustrated in FIGS. 13B, 14B, 15B, and 16B.

(45) TABLE-US-00002 TABLE II Comparison of Handle Weight to Total Hammer Weight & Handle Weight Hammer Brand/ Handle Weight % Ratio of Head Weight Handle Material of Total Weight to Handle Weight Tool Driven Framer 14.1% 6.08 (hollow core)/ Carbon Fiber/Kevlar Tool Driven Builder 12.7% 6.89 (hollow core)/ Carbon Fiber/Kevlar Tool Driven Framer 17.3% 4.77 (foam core)/ Carbon Fiber/Kevlar Tool Driven Builder 15.6% 5.39 (foam core)/ Carbon Fiber/Kevlar Stiletto Ti-bone/ 52.5% 0.91 Titanium Stiletto 14P/ 49.3% 1.03 Polycarbonate Estwing 22S/ 45.1% 1.22 Steel Estwing Big Blue/ 35.0% 1.86 Steel DeWalt 15 Old/ 50.8% 0.97 Steel - I-Beam DeWalt 15 New/ 52.6% 0.90 Steel Stamped DeWalt 17 S/ 42.0% 1.38 Hickory Straight DeWalt 17 C/ 26.1% 2.84 Hickory - Curved DeWalt 20/ 49.9% 1.01 Steel Powerstrike Curved/ 42.9% 1.33 Aluminum Powerstrike Straight W/ 41.3% 1.42 Aluminum + Wrap Powerstrike Straight/ 43.6% 1.29 Aluminum Vaughan 23/ 29.7% 2.36 Hickory Husky 21/ 37.4% 1.68 Hickory Vaughan 21/ 34.6% 1.89 Fiberglass Hart 21/ 35.4% 1.83 Fiberglass

(46) Additionally, it is another aspect of the present invention to have a head weight to handle weight ratio above 3:1. As evident from Table II above, prior art hammers have a head to handle weight ratio that is less than 3:1, with most prior art hammers having a ratio between 1 and 2. Conversely, embodiments of the present invention have a head to handle weight ratio that is greater than 4:1. Accordingly, it is another aspect of the present invention to have a ratio of head weight to handle weight that is above 4:1 while maintaining the preferred length between 35 and 47 centimeters and a total weight between 600 and 1200 grams as plotted in FIGS. 15A and 15B, respectively.

(47) Another aspect of the present invention is an apparent handle weight less than 10% of the total hammer weight when the hammer is measured in the fully assembled configuration. The apparent weight of the head and handle of the hammer has a significant effect on the performance and comfort of the tool for the worker. The apparent weight is measured by placing the head of the hammer on a first scale and the base of the handle on a second scale. The head is positioned on one scale such that the head rests on the edge of the striking face proximate to the handle and the base of the handle rests on the second scale that is separated from the head scale by the length of the hammer. Accordingly, the weight reading shown on the scale under the head is the apparent head weight and the weight reading shown on the scale under the handle is the apparent handle weight. In some embodiments, the apparent handle weight can actually be 0% of the total weight such as when the hammer CG is so far towards the opposite end of the base that it is not only located within the head, it is located within the lateral projection of the striking face (i.e. within the diameter extending perpendicular to the striking face sitting on one scalealong the axis of the head) so that the hammer can actually balance on the striking face. Hammers with lighter apparent handle weights have less impact shock and the weight distribution of the present invention results in apparent weights of head and handle that are significantly different than any hammer in the prior art, as described in Table III below.

(48) TABLE-US-00003 TABLE III Hammer Measurements (Two Scale Methodology) Apparent Apparent Apparent Apparent Handle Total Head Handle Hammer Weight % Hammer Brand/ Weight Scale Scale Length of Total Handle Material (g) (g) (g) (cm) Weight Tool Driven 641 613 28 43.50 4.4% Framer (foam core)/Carbon Fiber/Kevlar Tool Driven 735 700 35 44.45 4.8% Builder (foam core)/Carbon Fiber/Kevlar Stiletto Ti-bone/ 893 624 269 43.66 30.1% Titanium Stiletto 14P/ 783 571 212 40.64 27.1% Polycarbonate Estwing 22S/ 946 721 225 40.32 23.8% Steel Estwing Big Blue/ 1086 860 226 45.40 20.8% Steel DeWalt 15 Old/ 861 623 238 41.91 27.6% Steel - I-Beam DeWalt 15 New/ 837 592 245 41.91 29.3% Steel Stamped DeWalt 17 S/ 830 690 140 45.09 16.9% Hickory Straight DeWalt 17 C/ 843 723 120 42.86 14.2% Hickory - Curved DeWalt 20/ 797 574 223 35.24 28.0% Steel Powerstrike 795 678 117 43.97 14.7% Curved/ Aluminum Powerstrike 772 643 129 45.09 16.7% Straight W/Aluminum + Wrap Powerstrike 804 686 118 45.09 14.7% Straight/ Aluminum Vaughan 23/ 927 794 133 44.45 14.3% Hickory Husky 21/ 949 783 166 45.72 17.5% Hickory Vaughan 21/ 929 745 184 40.64 19.8% Fiberglass Hart 21/ 1099 862 237 45.72 21.6% Fiberglass

(49) Additionally, the apparent head weight and handle weight further illustrate how the weight of the present invention is targeted towards the head of the hammer. As shown in FIG. 16 and Table III above, the apparent handle weight makes up less than 5% of the apparent weight of the hammer. Conversely, the apparent handle weight of prior art hammers are above 14%. The apparent handle weights are plotted against relative to the total hammer length and the total hammer weight in FIGS. 16A and 16B, respectively.

(50) Another aspect of the handle of the present invention is the proximity of the inflection point 24 to the handle's base 56 on the handle's front side 64 that faces the striking surface 16. The inflection point 24 is situated between a concave shape 66 closest to the base and a convex shape 68 as shown in FIG. 3 and generally described above. The concave shape 66 extends a distance 70 from the handle's base 56 to the inflection point at its end which is also the beginning of the convex shape 68. Accordingly, as indicated above, the distance 70 of the inflection point from the base is less than five (5) diameters of the striking face (d.sub.IP<5D.sub.SF) and is preferably less than four (4) diameters. As shown in FIG. 3B, a curve chart shows the degree of curvature with the concave shape closest to the base and the inflection point at the intersection between the concave shape and the convex shape.

(51) The variations in the concave shape 66 and convex shape 68 relative to the curvature on the handle's backside 100 result in different gripping axes 98 relative to the overall longitudinal axis 50 of the handle. Accordingly, the variations in the gripping axes 98 in different sections of the handle provide for different gripping positions 96 in these handle sections. As shown FIG. 4A, the concave outer surface 66 defines a power gripping section 96a where the angle of the gripping axis 98a is substantially behind the handle's longitudinal axis 50. This axis is more useful for framing work in which excess power to drive a nail is desired and allows the user's wrist to be in a more neutral position at impact during typical framing positions as compared with the straight gripping section 96b and the precision gripping section 96c. In the preferred embodiment, the angle of this power gripping axis 98a is 10-20 behind the longitudinal axis 50 of the handle. As shown in FIG. 4A, the power gripping axis 98a is rotated away from the striking face 16 and toward the claw 86.

(52) As shown in FIG. 4B, the precision gripping section 96c corresponds with the user gripping the handle around the inflection point 24, i.e. the grip is over a portion of the convex shape and a portion of the concave shape. When a user grips the handle in the precision section 96c, the precision gripping axis 98c is rotated forward towards the striking face 16 relative to the longitudinal axis 50 of the handle. The precision section 96c is preferably used for finishing work and provides a gripping angle 98c that is 5-10 in front of the handle's longitudinal axis. As shown in FIG. 4C, the straight gripping section 96b corresponds with the user gripping the handle between the precision gripping section 96c and the power gripping section 96a, i.e, within the concave shape, where the straight gripping axis 98b is parallel to the longitudinal axis 50 of the handle. A user gripping the handle in the straight section 96b has a neutral gripping angle 98b substantially parallel to the longitudinal axis 50 of the handle.

(53) Accordingly, the inflection point 24 provides three separate and unique gripping sections 96 that allow a user to complete multiple jobs, including framing work and finishing work, without necessarily switching hammers. Additionally, the inflection point allows a user to effectively and ergonomically use the hammer 10 in multiple positions without sacrificing leverage since all three gripping sections 96 are proximate to the base of the handle 56. Yet, the relatively straight overall profile of the entire handle 14 does not interfere with the work surface compared to the axe handles seen in the prior art. When gripped with the middle two fingers at the inflection point, the natural gripping axis is rotated towards the striking face relative to the longitudinal axis of the handle which can be seen in FIG. 4B. Additionally, when gripped with the middle two fingers where the line tangent to the concave outer surface is parallel to the concave outer surface, the natural gripping axis is parallel to the longitudinal axis of the handle which can be seen in FIG. 4C. Additionally, when gripped with the two middle fingers where the line tangent to the concave outer surface intersects the claw portion of the head, the natural gripping axis is rotated away from the striking face or toward the claw which can be seen in FIG. 4A.

(54) Another aspect of the handle are the multiple composite layers that collectively form the handle 14 as shown in FIG. 5A. The handle is formed by laying carbon fiber and Kevlar layers over a lightweight, non-structural internal core 32 that serves only as a guide to shape the carbon sleeves as the epoxy polymer cures. The composite layers are formed around the internal core 32 that in the preferred embodiment is made of foam 32a. An internal layer 26a of composite, preferably carbon fiber, is fit around the internal core 32. Subsequently, one or more intermediate composite layers 26c are formed around the inner layer 26a and are then covered by the external layer 26b which is made from Kevlar in the preferred embodiment.

(55) The carbon fiber layers of the handle 14 provide increased stiffness which increases the handle's natural frequency of vibration. Some conventional hammer handles are more flexible and have low vibration frequencies that can cause tendon problems. In comparison, the higher vibration frequencies of the stiffer carbon fiber handle, without any titanium spar or other plate along the length of the handle, are much more effectively absorbed by the skin and flesh of the worker's hand. Another benefit of the handle's increased stiffness is that the user perceives the hammer as more effective and accurate, which increases the user's confidence in the tool. Additionally, because impacts with the present invention have so little shock on the user's hand, the user is naturally encouraged to swing the tool harder. Conversely, conventional hammers with conventional weight distribution discourage forceful swings as the user subconsciously protects their hand from extreme shock. Additionally, carbon fiber handles do not have the failure modes associated with fatigue as found in wood, aluminum, titanium, and steel handles. For example, hammers with steel handles are subject to pinging caused by stress fractures within the structure of the handle.

(56) At impact, as depicted in FIGS. 5B, 5C and 12, a hammer handle 14 is under tremendous stress and the force of impact tends to rotate the head relative to the handle such that the claw 86 points toward the handle and the striking face 16 points away from the handle as illustrated in FIG. 5C. During this rotation, the backside 100 of the handle is under compression and the front side 64 of the handle is under tension. Accordingly, the handle shape near the head is designed so that the distance between the tension section and compression section is as large as reasonably possible in order to strengthen this inherently weak area of the hammer. Additionally, a hump 102 as depicted in FIG. 5B on the backside 100 of the handle 14 of the present invention allows the shell of the handle to flex slightly, acting as a spring to absorb the rotational motion of the head at impact. In effect, the hump 102 keeps the striking face 16 in contact with the nail 80 slightly longer and thereby facilitates more energy transfer to the nail. The humped spring 102 also reduces the likelihood of stress fractures in the composite handle 14. Additionally, the stresses in the handle are not uniform from the mounting end 74 of the handle to the base 56 of the handle. The stresses are largest near the head 12 and get progressively smaller towards the base. Accordingly, as shown in FIG. 5A multiple intermediate layers 26c are used in varying lengths in order to keep the handle as light as possible, but stiff during use. As described herein, the internal layer 26a and external layer 26b are the full length of the hammer handle 20 and the intermediate layers 26c are shorter in order to provide greater composite material thickness where the stress is highest.

(57) The intermediate composite layers 26c of carbon fiber are positioned around the inner layer 26a proximate to head 12 of the hammer which then extends a length 72 towards the base 56. However, the length 72 of the intermediate layer 26c is shorter than the handle length 54. Accordingly, it is an aspect of the intermediate layers 26c to only extend across parts of the handle 14 that experience high stress when the hammer is swung and impacted. For example and as discussed in the hump design 102 above, the backside 100 of the handle directly below the head may have multiple layers of composite material as this is a point of high stress, as shown in FIG. 5A.

(58) It is another aspect of the handle of the present invention to have an external layer 26b that covers the inner layer 26a and extends the entire length of the handle 54. Accordingly, the intermediate layers 26c are sandwiched between the inner layer 26a and external layer 26b as depicted in FIG. 5A. In the preferred embodiment, the external layer is made of Kevlar but other types of lightweight, high strength materials may be used. Accordingly, the multiple composite layers collectively form the handle 14 of the present invention. The Kevlar composite layer is preferred as the outer layer because Kevlar fails by becoming stringy and fuzzy rather than splintering which is the failure mode of most other composite layers that may be used, such as fiberglass and carbon fibers. When carbon fiber fails, it fails catastrophically and can separate into multiple pieces with jagged edges so the failure mode of Kevlar as the outer layer is preferred. Using this as an external layer 26b prevents splinters and lacerations during a handle failure and keeps the head attached to the handle, even under catastrophic failure conditions. Additionally, the Kevlar external layer can be dyed different colors for individual choice in hammer color. A surface coating may be applied to the handle, such as a clear coat or possibly even which may help protect the outer composite layer because as the surface layer of reinforcing epoxy wears through normal use, the actual composite fibers will be exposed which can splinter and cause irritation to the user's hand. Additionally, the gripping section preferably includes a low durometer rubber layer or a shrinkable rubber section to provide a tacky, satisfying grip.

(59) In another aspect of the preferred embodiment of the present invention, the internal core 32 is made up of a foam core 32a and a reinforcing block 34 embedded within the layers of composite at the mounting end 74 of the handle 14. Examples of the internal core 32 and reinforcing block 34 can be seen in FIG. 6. This reinforcing block 34 serves to prevent the high compression forces of the set screw 36a from crushing the carbon fiber handle, as described below. Additionally, by adjusting the material and shape of the reinforcing block 34, it can be used to alter the overall weight of the hammer. Although the reinforcing block 34 is metal in the preferred embodiment, a reinforcing block made of a carbon fiber 34a structure may also be used which can be seen in FIG. 6D. Acceptable carbon fiber structures include but are not limited to honeycombed, grid and lattice structures. This lets the user choose the hammer weight that best fits both their personal preference and the application, like framing, siding, and finishing. The shape of the reinforcing block 34 can also be adapted to work as a fastener preload spring to compress the set screw to its correct specification. This preload spring function can work in conjunction with the spring force provided by deformation of the carbon fiber around the reinforcing block. Additionally, the preferred reinforcing block includes an undercut 104 on the set screw side as a safety feature to ensure that if the set screw were to loosen during use, the head would stay attached to the handle.

(60) As described above, the composite layers are formed around the internal core 32. However, once the composite layers have been set, the internal core does not provide structural support or strength. To protect the composite shell at the base of the handle, a protective plug 106 made from resin, plastic, rubber or similar material is inserted inside the shell connected to the core 32 and is held in place by the composite layers once they have cured. Additionally, the plug has a vent hole 108 for expanding foam. In the preferred embodiment the foam core 32a extends from the plug 106 at the base 56 of the handle to the reinforcing block 34 held within the mounting end 74 of the handle attached to the head 12. Accordingly, the composite layers may be formed around the foam core 32a, reinforcing block 34, and plug 106 which together form the internal core in the preferred embodiment. In another embodiment, the foam core may not be used at all and the internal core 32 can be comprised of a protective plug 106, a hollow core 32b and the reinforcing block 34. Regardless of the embodiment, when the reinforcing block is used at least one of the foam core, hollow core, or other core material extends from the reinforcing block to the protective plug at the base of the handle. Accordingly, it is an aspect of the core to be lightweight and only provide shape to the composite layers as they are being laid and formed, which is described below.

(61) In another aspect of the preferred hammer, the reinforcing block is held within the internal core 32 at a position opposite the base, which defines the mounting end 74. At least a portion of the mounting end 74a of the handle is inserted into the head void 94 substantially perpendicular to the end face 46a of the head, as shown in FIG. 6 and FIG. 7. Accordingly, the head 12 and handle 14 are connected at the mounting end 74 and the reinforcing block 34 may be used to provide a more secure connection. In the preferred embodiment a set screw 36a secures the handle to the head as the set screw extends through a threaded fastener 112 and a hole 114a in a front plate 110 of the head 12. The screw is preferably aligned with the central point of the striking face 16 and the head's longitudinal axis 42. The set screw 36a is then tightened until at least a portion of the set screw compresses into the composite layers surrounding the reinforcing block 34. Accordingly, the reinforcing block prevents the relatively thin layer of carbon fiber that forms the structural part of the handle from crushing under the forces applied by the set screw.

(62) In another embodiment the handle 14 does not have the reinforcing block 34 and the set screw 36a extends through the front side 64 of the handles 14 mounting end 74 and compresses into the composite layers of the backside 100 or extends completely through a hole 114b on the back side of the handle 100, as shown in FIG. 7A. In this embodiment it is preferred that the mounting end 74 of the handle has a thicker composite layer 116, as in FIG. 7B, sufficient to resist the pressure applied by the set screw 36a. Like in FIG. 7A, the set screw extends completely through the handle and the screw does not impinge the handle itself but instead presses against the back plate of the head 118. Accordingly, the back plate 118 and front plate 110 pinch the handle and lock it in place. Additionally, other means for connecting the head to the handle may be used including but not limited to those described below.

(63) In another embodiment, the handle 14 is mounted to the head 12 by securing the head within the handle with an adhesive 36f. As is traditionally done with polycarbonate and other plastic handles, an epoxy or glue may be used. Although inexpensive, using an adhesive 36f to attach the head to the handle makes the handle difficult to replace. Accordingly, the preferred adhesive is an epoxy resin that can be baked out by a user allowing the handle or head to be subsequently replaced. Additionally, an adhesive can also be used in combination with the other embodiments shown in FIGS. 6 and 7, including the preferred handle having a reinforcing block 34 in the mounting end of the handle held secured into the head void 94.

(64) In the embodiment depicted in FIG. 7C, the handle is mounted to the head by clamp 36e. In this embodiment, the set screw 36a is also used and freely rotates within the clamp attachment 36e and the front clamp 120 moves relative to the fixed rear clamp 122 which is integrated into the back plate of the head 118. Additionally, a curved clamp 36e offers a more secure attachment because the curved clamp applies even pressure along more surface area of the handles mounting end 74. Accordingly, the composite layers do not necessarily need to be thickened to withstand the pressure exerted by the set screw if the reinforcing block is not used, as discussed above and shown in FIG. 7B. This embodiment for the head may also be used with a handle formed from a different lightweight material, such as a tube made from aluminum or titanium.

(65) In another embodiment, the handle is mounted to the head by two opposing wedge fasteners 36c that lock the handle into the head void 94, which can be seen in FIG. 7D. While wedges have been used to attach hammer handles for centuries, they are usually driven into the center of a wood handle to expand a wood to grip the inside surface of an eye in the head. Following that method with a carbon fiber handle is counterproductive because it may crack the carbon fiber at the high stress head/handle joint. However, when opposing wedges are used, the wedge fasteners 36c compress the handle towards the striking face 16 without damaging the composite material. Additionally, the wedge fasteners 36c may be held in place by set screws or some other method to prevent drifting while using the hammer.

(66) In the embodiment depicted in FIG. 7E, the handle is mounted to the head by an expanding star nut 36d extending through the top side of the head 46 into the mounting end 74 of the handle. Although traditionally used to attach bike forks to handle bars, the star nut 36d locks the head of the hammer to the handle from the top side rather than the striking face 16 side of the head. Additionally, this method requires two fasteners, the set screw 36a and expanding star nut 36d.

(67) In another embodiment, the handle is attached to the head using a wedging system, shown in FIGS. 7F, 7G and 7H. In this embodiment the side wall of the mounting end 74b are canted outward and secured in a wedge shaped head void 134, with the front side of the wedge shaped head void 134a narrower than the backside of the wedge void 134b. The handle is inserted into the wedge shaped head void and then locked in place with the back plate 118. The back plate is secured with screws 134c to prevent the back plate from dislodging. Those having skill in the art will appreciate that repeated impacts will serve to drive the wedge shaped mounting end further into the wedge shaped head void, thereby tightening the handle to head joint with use. The end plate may be curved slightly to provide spring force to push the wedge shaped mounting end of the handle into the wedged shaped head void. Additionally, the back plate is installed with a slight taper such that the top of the back plate 118a proximate to the end plate is further from the striking face than the opposite end of the back plate 118b that is closer to the striking face. Accordingly, the handle cannot be withdrawn from the head under prying impacts or from general use before repeated impacts have driven the handle to solid contact with the wedged sides of the handle head void.

(68) In addition to the light weight handle in the preferred embodiment the hammer 10 has a number of new usability features while maximizing strength and durability. The striking face 16 is field replaceable simply by screwing a new striking face onto the head 12. This way, the same hammer can be used for both framing and finish applications. In the preferred embodiment, the striking face 16 is secured to the head by the end of the set screw 36a opposite that attaching the head and handle. The front plate 110 of the head consists of the hole 110 through which the set screw passes 36a, shown in FIGS. 6B, 6D, 7A, 7B and 7D. In the preferred embodiment the hole 110 is centered on the front plate, eighteen millimeters in diameter and the set screw is an M162, however it will be appreciated by those having skill in the art that set screws of varying sizes could also be used and the size hole 110 in the of the front plate will vary accordingly. Thus, the single set screw goes through the front plate 110 and the head void 94 and pins the handle 14 to the back plate 118 while protruding far enough towards the striking face 16 to serve as an attachment stud 124 for the modular striking face 16 which can be seen in FIGS. 6B, 6D and 7.

(69) Additionally, the front plate 110 consists of an overstrike portion 126 extending below the head 12 along the front side of the handle 64. The overstrike portion 126 is no greater than one striking face diameter 60 away from the longitudinal axis of the head 42. Additionally, the overstrike portion 126 is wide enough to protect the composite handle from damage resulting from miss hits. In the preferred embodiment, the overstrike portion 126 is an extension of the front plate 110 towards the base of the handle 56. However, in another embodiment the overstrike portion may be a protective metal plate embedded under the external layer of composite material on the handle. Regardless of the embodiment, the overstrike portion is designed to protect the composite handle proximate to the head of the hammer.

(70) An aspect of the striking face shown in FIG. 10 is a malleable striking surface 88 having embedded grit materials 90a. The malleable striking surface 88 is an improvement over conventional steel striking faces but is similarly mounted to the head of the hammer. The striking surface area 88a of the steel striking face contains a shallow indentation 88b having tapered walls 88c depicted in FIGS. 10A and 10C. A wad 90 made from a deformable material, typically silicon bronze, aluminum bronze, lead or another similar alloy, is placed within the striking face indentation 88b and extends beyond and over the top of the tapered outer walls 88c as shown in FIGS. 10B and 10D. The wad 90 is held within the indentation 88b by the tapered walls 88c that create an interlocking fit. Additionally, the wad is welded into the indentation causing the wad to bond with the steel substrate of the striking face. The grit 90a embedded into the wad 90 are small, hard particles and are preferably aluminum oxide or silicon carbide, but similar materials may also be used. The particles are roughly 0.25 to 0.75 millimeters in diameter and are homogeneously distributed throughout the material. In effect, the alloy striking surface has a textured and scratchy outer face.

(71) In operation, when the malleable striking surface 88a hits a fastener, like the head of a nail 80, with sufficient force the striking face will deform around the struck surface and thereby prevent the striking face from sliding off. Additionally, the repeated nail impacts on the deformable material knead the surface of the striking face 88a, burying some of the grit 90a particles and exposing others. After multiple strikes, the malleable material may mushroom over the edges of the steel striking face 88a, but hammering the mushroomed material on the side of the striking face will fold the deformable material back onto the striking surface 88a. Additionally, as a user is unlikely to strike a nail at the same position on the striking face each swing, the malleable striking surface 88a remains reasonably flat causing neither miss-hits nor flush setting blows to leave unsightly imprints on the surface the user is striking. Additionally, if the hammer is not swung with enough force to deform the malleable material, the embedded grit 90a provides a textured surface to prevent slipping. In addition to lighter blows, the malleable surface may deform if the hammer is swung at an angle and the striking face does not have a flush impact with the nail head or other surface being struck.

(72) In another embodiment, shown in FIG. 11, the striking face may have a carbon spool spring striking face 128 that increases striking efficiency and provides improved user feedback. The carbon spool spring provides a progressive spring effect by using a cylinder of composite fiber as the deformable body, rather than having the deformation occur on the impact surface. The carbon spool spring is made up of the striking face 128a which can be smooth, textured, or micro textured, and a threaded mating component 128b attaching the striking face to the set screw 36a on the hammer head 12. The striking face 128a and threaded mating component 128b are connected using an epoxy glue to form a thin, stiff neck 128c. Both the striking face and mating component are roughed up to provide a positive physical interaction with the epoxy connecting the two. Additionally, composite fiber tape is wrapped around the neck which ultimately provides the spring action once the entire assembly 128 is mounted onto the head of the hammer. In operation, the epoxy neck 128c is pulverized after the first few impacts and the carbon wrap 128d provides the spring. This spring effect is particularly effective during off-center strikes as the forward, impacting portion of the striking face pivots toward the off-center strike rather than throw the entire head assembly off to one side at impact. With a conventional, solid striking face, an off-center strike tends to bend the nail toward the center of the striking face as the striking face drags laterally across the head of the nail. Conversely, with the carbon spool spring striking face 128, the pivoting action prevents the lateral drag across the nail and prevents bending nails on off-center strikes.

(73) Another aspect of the head of the present invention is a double nail-pull 38 made up of a pair of notches 76a,76b on opposite sidewalls 78a,78b of the head, slightly off-center from the side of the handle which can be seen in FIG. 9. The first notch 76a engages the head of the nail 80a and a user may rotate a portion of the nail 80 of out the wall, board or similar surface to first position 82 as shown in FIGS. 9A and 9B. Subsequently, the head of the hammer can be repositioned into a second position 84 where the second notch 76b engages the head of the nail 80a and the first notch 76a engages a shank of the nail 80b as shown in FIG. 9C. Accordingly, the hammer can again be rotated about the nail-pull and the nail can be completely pulled out of the wall, board or similar surface as shown in FIG. 9D. Accordingly, the double nail-pull 38 increases the mechanical advantage where a user can engage the nail in more than one position. The double nail-pull mechanical advantage is nearly 400% higher than a conventional nail pulling claw. Additionally, since it is possible for a nail to reach directly from the notch on one side wall all the way to the notch on the other side wall, even the longest nails can be pulled almost completely free of the wood using very high mechanical advantage. Additionally, since the side nail pulls are offset from the side of the handle, the user can pull nails with a very high mechanical advantage by pulling the handle sideways and towards the claw, but may also pull nails with a lower mechanical advantage and a larger range of motion by pulling the handle sideways and towards the striking face. Additionally, the notches have a small chamfer routed along the inside of the opening to provide a more effective profile for the nail pulling feature.

(74) Another aspect of the head of the present invention is a magnet insert 40 affixed within at least one of the side walls 78 of the head, as shown in FIGS. 8B and 8C. This magnet insert 40 is made up of a high-strength rare-earth magnet embedded into least one of the side walls of the head. This magnet allows the user to start nails by placing a nail head against the magnet and swinging the hammer sideways. Unlike conventional nail starters on typical hammers of the prior art, the present invention places the nail starter on the side of the head. Accordingly, by aligning the nail starter perpendicular to the shortest axis of the head, nails can be started in much tighter environments when compared to the nail starters on other hammers available today. Additionally, the magnet insert is sized so that the nail head overlaps the magnet and sits on the harder steel surface surrounding the magnet.

(75) During the preferred method of manufacturing of the handle, the reinforcing block 34 is machined to the desired dimensions. Though the design can vary, all reinforcing blocks have dimensions matching the mounting end of the handle and receiving feature on the head. Additionally, the reinforcing block is machined to compensate precisely for the thickness of the composite fiber layers. The blocks are machined at 90 degrees to ensure that the finished head is properly aligned with the handle. Also, the undercut section 104 is machined for set screw contact. Next, a foam handle blank is cast and the reinforcing block 34 and protective plug 106 are placed at opposite end of a female mold made from a master handle. A two-part expanding foam is poured into the mold and allowed to expand until the foam expands to the proper shape and bonds to the reinforcing block and protective plug.

(76) Once the foam has expanded and bonded to the reinforcing block the internal core 32 is complete and removed from the mold where it is covered with the inner composite layer 26a, extending the entire length of the internal core. The inner composite layer is wetted with epoxy and the intermediate composite layer 26c is laid over the inner layer firstbut this section only extends from the reinforcing block 34 to the top of the precision gripping section. As discussed above, the intermediate layer extends from the head side of the internal core towards the base. In the preferred embodiment the intermediate layer is approximately eight inches (20 cm) long. Another intermediate layer is laid which is approximately fourteen inches (36 cm) long and reaches just to the neutral section of the handle, proximate to the inflection point. Then, another intermediate layer 26c is laid which is approximately fifteen inches (38 cm) long. However, the number and length of the intermediate layers may be altered to change the stiffness and natural flex points of the handle. Finally, the full length external layer 26b of Kevlar is laid on the handle. Each new layer of composite is wetted with epoxy and the excess is wiped off.

(77) Once all the layers have been formed, the handle 14 assembly is inserted into a specially treated heat shrink tubing. A heat gun or oven is then used to shrink the tubing to compress the layers of composite material and epoxy while the handle cures. After 24 hours, the shrink wrap is removed from the handle, and the excess carbon composite layers are cut from both ends with a diamond saw. The grip end of the handle proximate the base 56 is dipped in a low durometer rubber or a shrinkable rubber section is applied to the outside of the grip end to provide a tacky, satisfying grip.

(78) A second embodiment of the handle manufacture is to use no internal structure at all. By using a two piece mold and an inflatable bladder, layers of composite are wrapped around the inflatable bladder. The bladder and carbon are then inserted into a hard-shell female mold. The bladder is then inflated, compressing the carbon and Kevlar layers against the outside of the mold until the polymer has cured sufficiently.

(79) The head 12, shown in FIG. 8A, is manufactured by welding pieces of plate steel together, making it easy to manufacture with ultra-high quality steel, stainless steel, or other exotic alloys which are not usually forgeable. A welded head has an additional advantage that by altering the thickness of the plates, the final weight of the head may be altered without having to retool forging molds. Welding allows the hammer head to be manufactured for specific applications as when welded with a silicon bronze filler metal that is better for pure impact applications since silicon bronze can deform further prior to cracking. However, where prying is more important, a different filler rod can be used to make the weld more homogeneous with the other metal parts. The side plate to claw welded joint reaches nearly to the end of the claw and consequently provides two advantages. First the tip of the claw can be ground to a relatively acute angle which improves the hammer's ability to dig under nails or in between boards for prying applications. Second, since the side plate joint covers the area where the claw would actually engage a nail during a nail pull, the claw tines are extremely strong.

(80) In the preferred embodiment, the head is made from several individual pieces of flat metal stock like high carbon steel, stainless steel or similar materials. These pieces are cut from a single sheet of metal using a plasma cutter and template, a CNC plasma cutter or water jet and a nut with a female internal thread or other threaded fastener is welded to the front flat plate 110 of the head proximate to the striking face 16. In the preferred embodiment, the internal threaded nut 112 is M162 mm, but it should be appreciated that other sized threads can be used. Additionally, for a front plate with sufficient thickness, the front hole 114a can be threaded. Then the end plate 46 is bent over a precision form to match the curve of the side walls 78. The head is then welded together using a TIG welding process and depending on application, the TIG filler rod may be silicon bronze or a metal rod that matches the chemistry of the flat plates more precisely. Lastly, the M16 female threaded screw nut 112 is welded to the front of the front plate 110 which receives the set screw when the head is attached to the handle. This piece can be a conventional nut, a round bar with a drilled hole that is threaded or any other threaded fastener. In another embodiment, the head could be manufactured by creating a male and female die set. The metal plates would be then cut out, but left attached with additional margin to accommodate the bend. This blank would then be bent by a male and female die that forms the near-final head shape.

(81) A final grinding operation removes excess weld material from the sides and sharpens the claw. The fully assembled heads are then heat treated to ensure that the metal has the ideal physical characteristics of hardness and pliability. Finally, the heat treated heads are tumbled in a vibratory tumbler with ceramic media to give the piece a pleasing, consistent finish. The heat treated heads may also be surface ground, wire brushed or finished with an abrasive pad. Subsequently, the entire hammer is ready to be assembled and a handle is inserted into the head and the set screw is tightened onto the handle. Lastly, a striking face is then tightened onto the exposed section of the set screw.

(82) The embodiments were chosen and described to best explain the principles of the invention and its practical application to persons who are skilled in the art. As various modifications could be made to the exemplary embodiments, as described above with reference to the corresponding illustrations, without departing from the scope of the invention, it is intended that all matter contained in the foregoing description and shown in the accompanying drawings shall be interpreted as illustrative rather than limiting. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims appended hereto and their equivalents.