[0001] This application claims the benefit of priority of U.S. provisional application serial no. 61/793,025, filed March 15, 2013, the disclosure of which is herein incorporated by reference in its entirety.

Field

[0002] This disclosure relates generally to power saws and particularly to a fastening system for a blade guard of a power saw.

Background

[0003] Power saws are used for cutting and shaping workpieces, such as, hardwood, manufactured wood products, construction lumber, metal construction materials, and the like.

One type of power saw, commonly referred to as a chop saw, typically includes a base configured for placement on a stand, a table, or on the ground. The base defines a workpiece support surface, which is used to support a workpiece to be cut by the chop saw. A support assembly of the chop saw extends from the base, and a cutting arm assembly is movably connected to the support assembly. The cutting arm assembly includes an electric motor configured to rotate a circular saw blade.

[0004] A workpiece is cut with the chop saw by moving the cutting arm assembly downward relative to the base, such that the rotating saw blade is moved through the workpiece.

After completing the cut, the cutting arm assembly is moved upwards to extract the saw blade from the kerf formed in the workpiece. [0005] On at least some chop saws, the cutting arm includes an upper blade guard that defines a blade guard space. An upper portion of the saw blade is positioned in the blade guard space, such that the upper blade guard covers approximately an upper half of the saw blade. Additionally, the cutting arm assembly includes a movable blade guard, sometimes referred to as a lower blade guard, which is configured to rotate about a hub relative to the upper blade guard. A biasing member biases the lower blade guard toward a closed position in which the lower blade guard covers most of a lower portion of the saw blade. When cutting a workpiece, the lower blade guard moves relative to the upper blade guard toward an open position, against the force of the biasing member, to expose a portion of the saw blade and to enable the saw blade to extend into the workpiece.

[0006] During the assembly process of known power saws, the lower blade guard is connected to the cutting arm assembly of the power saw with a fastener. Typically, the assembler adjusts the torque applied to the fastener so that the lower blade guard is sufficiently connected to the cutting arm assembly and so that the lower blade guard pivots easily with respect to the upper blade guard. Accordingly, the assembler carefully adjusts the torque applied to the fastener in a time consuming and tedious process.

[0007] Therefore, it is desirable for a power saw to include a lower blade guard that is easily and quickly connected to the cutting arm assembly of the power saw.

Summary

[0008] According to an exemplary embodiment of the disclosure, a blade guard assembly for a power saw includes a bolt member, a blade guard housing, a mounting plate, an engagement nut, and a biasing member. The bolt member includes a head defining a first shoulder, a pivot shank extending from the head and defining a second shoulder, a support shank extending from the pivot shank, and a threaded shank extending from the support shank and located opposite from the head. The blade guard housing defines a blade space for at least partially covering a saw blade of a power saw and includes a hub defining a hub opening configured to pivotably receive the pivot shank therethrough and to seat on the first shoulder. The mounting plate is supported by a cutting arm of the power saw and defines a mounting opening configured to nonrotatably receive the support shank therethrough and to seat on the second shoulder to position the mounting plate a fixed minimum axial distance from the first shoulder. The engagement nut is threadingly engaged to the threaded shank and seated on the mounting plate. The biasing member includes a first end portion supported by the blade guard housing, a second end portion supported by the mounting plate, and a coil portion configured to receive the pivot shank therethrough. The coil portion defines a first axial height that is equal to or less than the fixed minimum axial distance. The fixed minimum axial distance is sized so that the coil portion of the biasing member remains uncompressed between the blade guard housing and the mounting plate.

[0009] According to yet another exemplary embodiment of the disclosure, a method of assembling a blade guard assembly of a power saw includes pivotably supporting a blade guard housing with a pivot shank of a bolt member configured to extend through a hub opening defined by a hub of the blade guard housing, the pivot shank extending from a head of the bolt member, the head defining a first shoulder and the pivot shank defining a second shoulder, the hub being seated on the first shoulder; and supporting a first end of a biasing member with the blade guard housing and supporting a second end of the biasing member with a mounting plate. The method further includes extending the pivot shank through a coil portion of the biasing member, the coil portion defining a first axial height; extending a support shank of the bolt member through a mounting opening defined by the mounting plate to seat the mounting plate on the second shoulder and to position the mounting plate a fixed minimum axial distance from the first shoulder; and threadingly engaging an engagement nut to a threaded shank extending from the support shank, the engagement nut being seated on the mounting plate. The first axial height is equal to or less than the fixed minimum axial distance. The fixed minimum axial distance is sized so that the coil portion of the biasing member remains uncompressed between the blade guard housing and the mounting plate after the engagement nut is seated on the mounting plate.

[0010] According to yet another exemplary embodiment of the disclosure, a power saw includes a base, a support arm extending from the base, a cutting arm pivotably supported by the support arm, and an upper blade guard supported by the cutting arm and configured to define a first blade space for receiving at least a first portion of a saw blade of a power saw. The power saw further includes a lower blade guard assembly supported by the cutting arm and having (i) a bolt member including a head defining a first shoulder, a pivot shank extending from the head and defining a second shoulder, a support shank extending from the pivot shank, and a threaded shank extending from the support shank and located opposite from the head, (ii) a blade guard housing defining a second blade space for receiving at least a second portion of the saw blade and including a hub defining a hub opening configured to pivotably receive the pivot shank therethrough and to seat on the first shoulder, (iii) a mounting plate supported by the cutting arm and defining a mounting opening configured to nonrotatably receive the support shank therethrough and to seat on the second shoulder to position the mounting plate a fixed minimum axial distance from the first shoulder, (iv) an engagement nut threadingly engaged to the threaded shank and seated against the mounting plate, and (v) a biasing member including a first end portion supported by the blade guard housing, a second end portion supported by the mounting plate, and a coil portion configured to receive the pivot shank therethrough, the coil portion defining a first axial height that is equal to or less than the fixed minimum axial distance. The fixed minimum axial distance is sized so that the coil portion of the biasing member remains uncompressed between the blade guard housing and the mounting plate.

Brief Description of the Figures

[0011] The above-described features and advantages, as well as others, should become more readily apparent to those of ordinary skill in the art by reference to the following detailed description and the accompanying figures in which:

[0012] FIG. 1 is a left side elevational view of a power saw including a lower blade guard and a lower blade guard fastening system as described herein;

[0013] FIG. 2 is a right side perspective view of the lower blade guard and the fastening system of FIG. 1 shown in isolation;

[0014] FIG. 3 is left side perspective view of the lower blade guard and the fastening system of FIG. 1 shown in isolation;

[0015] FIG. 4 is an exploded view of the lower blade guard and the fastening system of

FIG. 1;

[0016] FIG. 5 is a cross sectional view of the lower blade guard and the fastening system of FIG. 1;

[0017] FIG. 6 is cross sectional view of a shoulder bolt of the fastening system of FIG. 1;

[0018] FIG. 7 is a bottom plan view of the shoulder bolt of FIG. 6; and [0019] FIG. 8 is an elevational view of a portion of a mounting plate of the fastening system of FIG. 1.

Detailed Description

[0020] For the purpose of promoting an understanding of the principles of the disclosure, reference will now be made to the embodiments illustrated in the drawings and described in the following written specification. It is understood that no limitation to the scope of the disclosure is thereby intended. It is further understood that the present disclosure includes any alterations and modifications to the illustrated embodiments and includes further applications of the principles of the disclosure as would normally occur to one skilled in the art to which this disclosure pertains.

[0021] As shown in FIG. 1, a power saw, shown as a metal dry cutter / chop saw 100, includes a base 104, a support arm 108 extending from a rear side of the base, and a cutting arm assembly 112. The base 104 is configured for placement on a work surface (not shown), such as a workbench, a power saw stand, or simply a ground surface. The base 104 is at least partially formed from a rigid material such as aluminum, steel, high strength plastic, composite materials or the like. An upper surface of the base 104 is configured to define a workpiece support surface 116. The workpiece support surface 116 is a substantially flat surface on which a user positions a workpiece (not shown) to be cut by the chop saw.

[0022] The cutting arm assembly 112 is configured for pivotal connection to the support arm 108 by a pivot shaft 120. In particular, the cutting arm assembly 112 is configured to pivot about the pivot shaft 120 to and between a raised position and a lowered position (not shown). [0023] The cutting arm assembly 112 includes a cutting arm 126, an electric motor 128, a saw blade 132 (shown in phantom), a handle portion 136, an upper blade guard 140, a lower blade guard housing / assembly 144, and a fastening system 148. The cutting arm 126 is formed from metal such as aluminum or steel. Alternatively the cutting arm 126 is formed from any high strength material as desired by those of ordinary skill in the art, such as high strength plastic, composite materials and the like.

[0024] The saw blade 132 is a circular saw blade configured to be mounted on an arbor assembly (not shown) of the cutting arm assembly 112. The saw blade 132 includes a highly abrasive perimeter, as typically provided on carbide tipped cutting blades for cutting metal. Alternatively, the perimeter of the saw blade 132 includes a plurality of cutting teeth for cutting wood, for example; or the saw blade is a diamond cutting blade for cutting tiles, for example.

[0025] The handle portion 136 is an approximately "D" shaped handle that fixedly extends from the cutting arm 126. The handle portion 136 is configured to be grasped by a user as the user pivots the cutting arm assembly 112 between the raised position and the lowered position.

[0026] The upper blade guard 140 fixedly extends from the cutting arm 126. The upper blade guard 140 is configured to cover approximately the upper half of the saw blade 132. To this end, the upper blade guard 140 defines a blade space 158 in which the upper half of the saw blade 132 is positioned. The upper blade guard 140 also defines a plateau 154 configured to receive a portion of the fastening system 148.

[0027] The lower blade guard housing 144 (shown separated from the cutting arm 126 in

FIGs. 2-5) is configured to be pivotally connected to the cutting arm 126 by the fastening system 148 about a hub 152 of the housing 144. The lower blade guard housing 144 is configured for rotational movement between a closed position (FIG. 1) and an open position (not shown). In the closed position, a blade space / cavity 156 (FIG. 2) defined by the lower blade guard housing 144 at least partially covers approximately the lower half of the saw blade 132 (i.e. any portion of the saw blade not covered by the upper blade guard). In the open position, the lower half of the saw blade 132 is exposed to enable the saw blade to contact the workpiece.

[0028] The chop saw 100 further includes a fence 160 and a clamp assembly 164. The fence 160 defines a surface 168 against which a workpiece to be cut is positioned. The fence 160 is pivotable relative to the base 104 to enable the user make angled cuts with the chop saw 100. The clamp assembly 164 is connected to the base 104 and is configured to secure a workpiece against the fence 160 so that the workpiece remains stationary during the cutting operation.

[0029] As shown in FIGs. 4 and 5, the fastening system 148 includes a bolt member shown as a shoulder bolt 172, a pivot bushing 176, a spring bushing 180, a biasing member 184, a mounting plate 188, and a fastener 192. The shoulder bolt 172 extends through a hub opening 194 defined by the hub 152 of the lower blade guard housing 144.

[0030] With reference to FIG. 6, the shoulder bolt 172 includes a head 190 and defines a pivot shoulder 196, a pivot shank / shaft 200, a connection shoulder 204, a support shank / shaft 198, a first bolt flat 208 of the support shaft, a second bolt flat 212 of the support shaft, a fastening shoulder 216, and a threaded shaft / shank 220 located opposite from the head. The pivot shaft 200 is located between the pivot shoulder 196 and the connection shoulder 204. The first flat 208 and the second flat 212 are positioned between the connection shoulder 204 and the fastening shoulder 216. The threaded shaft 220 extends from the fastening shoulder 216. In another embodiment, instead of the shoulder bolt 172 the fastening system 148 includes any suitable fastening element or fastening component.

[0031] With reference to FIG. 7 the first flat 208 is spaced apart from the second flat 212.

The first flat 208 and the second flat 212 form a "double-flat connection" when inserted into a correspondingly shaped mounting opening 224 (FIG. 8) in the mounting plate 188. The double- flat connection prevents rotation of the shoulder bolt 172 relative to the mounting plate 188, when the support shank 198 is received by the mounting opening 224.

[0032] With reference again to FIG. 4, the pivot bushing 176 is disposed in the hub 152 and defines an opening 240 in which the pivot shaft 200 of the shoulder bolt 172 is configured to be positioned. The pivot bushing 176 includes an interior bearing surface 242 that is configured for rotation relative to the pivot shaft 200 of the shoulder bolt 172. The pivot bushing defines an axial height 250.

[0033] The spring bushing 180 defines an opening 244 (FIG. 4) through which a portion of the lower blade guard housing 144 extends. The spring bushing 180 is positioned in a pocket 246 (FIG. 5) defined by the lower blade guard housing 144. The spring bushing 180, in one embodiment, is configured to rotate with the lower blade guard housing 144. The spring bushing 180 is received by a coil portion 251 of the biasing member and is configured to receive the pivot shank therethrough. The spring bushing 180 defines an axial height 253.

[0034] The biasing member 184 is a torsion spring that is positioned in the pocket 246 and is configured to receive the spring bushing 180. The basing member 184 includes a spring end portion 248, a spring end portion 252, and a coil portion 251 configured to receive the pivot shank 200 therethrough and defining an axial height 255. The spring end portion 248 is supported by the lower blade guard housing 144 and is configured to rotate with the lower blade guard housing. The spring end portion 252 is supported by the mounting plate 188 and is configured to remain generally stationary in response to rotation of the lower blade guard housing 144 relative thereto. In particular, the spring end 248 is positioned on a spring support member 260 that is connected to the mounting plate with a fastener 256. Movement of the spring end 248 relative to the spring end 252 generates the biasing force that biases the lower blade guard housing 144 toward the closed position.

[0035] As shown in FIG. 1, the mounting plate 188 is connected to the upper blade guard

140 of the cutting arm assembly 112. In particular, a fastener 264 (FIG. 1) connects a first end of the mounting plate 188 to the upper blade guard 140 and a fastener 266 (FIG. 1) connects a second end of the mounting plate to the upper blade guard. The mounting plate 188 is positioned in the plateau 154 defined by the upper blade guard 140.

[0036] With reference to FIGs. 4 and 8, the mounting plate 188 includes an opening structure 228 that defines the opening 224 and includes an opening flat 232 and another opening flat 236. The shoulder bolt 172 is positionable in the opening 224 such that the flat 208 contacts the flat 232 and the flat 212 contacts the flat 236. Accordingly, the flats 208, 212, 232, 236 cooperate / interlock to prevent rotation of the shoulder bolt 172 relative to the mounting plate 188. Also, when the shoulder bolt 172 is positioned in the opening 224, the connection shoulder 204 contacts the opening structure 228 so that the mounting plate is seated on the connection shoulder 204.

[0037] The fastener 192 is an engagement nut or a lock nut that is configured to be mounted on the threaded shaft 220 of the shoulder bolt 172 and seated on the mounting plate 188. [0038] As also shown in FIGs. 4 and 5, a linkage pin 268 extends through a linkage opening 272 in the lower blade guard housing 144. As shown in FIG. 1, the linkage pin 268 cooperates with a linkage arm 276 to move the lower blade guard housing 144 to the open position as the cutting arm assembly 112 is moved toward the lowered position.

[0039] In operation, the fastening system 148 simplifies the assembly process that includes pivotally connecting the lower blade guard housing 144 to the cutting arm 126 and/or the upper blade guard 140. As shown in FIG. 4, the assembly process includes press-fitting the pivot bushing 176 into the hub opening 194 in the lower blade guard housing 144. Then, the pivot shank 200 is inserted through the opening 240 in the pivot bushing 176 and the hub opening 194 so that the hub 152 and the pivot bushing 176 are seated on the first shoulder 196.

[0040] Next, the linkage pin 268 is inserted through the opening 272. Then, the spring bushing 180 and the biasing member 184 are positioned in the pocket 246 of the lower blade guard housing 144.

[0041] To continue the assembly process, the mounting plate 188 is positioned to receive the threaded shaft 220. During insertion of the threaded shaft 220 into the opening 224, the shoulder bolt 172 is rotated so that the flat 208 is positioned against the flat 232 and the flat 212 is positioned against the flat 228. Also, the connection shoulder 204 is positioned against the mounting plate 188. Thereafter, the fastener 192 is connected to the threaded portion 220.

[0042] The shoulder bolt 172 enables the fastener 192 to be tightened to a desired torque level without affecting the ability of the lower blade guard housing 144 to pivot relative to the mounting plate 188. This is because as the fastener 192 is tightened, the mounting plate 188 is squeezed between the connection shoulder 204 and the fastener 192. A minimum axial distance 280 (FIG. 5) is defined between the pivot shoulder 196 and the mounting plate 188 and is determined by the length of the pivot shaft 200. The minimum axial distance 280 is not based on the tightness of the fastener 192. Also, the shoulder bolt 172 controls the tolerance stack-up of the components of the fastening system 148. The axial height 255 of the coil portion 251 is equal to or less than the fixed minimum axial distance 280 to enable the biasing member 184 to operate smoothly and without binding or compression of the coil portion 251. Additionally, the axial height 253 of the spring bushing 180 and the axial height 250 of the pivot bushing 176 are equal to or less than the minimum axial distance 280 so that the spring bushing and the pivot bushing remain uncompressed between the blade guard housing 144 and the mounting plate 188.

[0043] The design of the fastening system 148 eliminates the need for fine adjustments of the torque of any fastener that connects the lower blade guard housing 144 to the cutting arm assembly 112. Accordingly, an assembler can quickly and easily tighten the fastener 192 to any desired torque level without affecting the ability of the lower blade guard housing 144 to pivot relative to the mounting plate 188. In particular, the fixed minimum axial distance 280 of the pivot shaft 200 is sized to that the coil portion 251 of the biasing member 184 remains uncompressed between the lower blade guard housing 144 and the mounting plate 188. Since the coil portion 251 is uncompressed it operates smoothly without binding. Also, the fastening system 148 reduces the number and the complexity of individual components and sub-assemblies included in portion of the cutting arm assembly 112 that includes the lower blade guard housing 144.

[0044] The double flat key connection between the shoulder bolt 172 and the mounting plate 188 (or any other form fitting connection between suitable elements) enables the fastener 192 to be tightened with just one tool, since a separate tool is not required to prevent rotation of the shoulder bolt. Tightening the fastener 192 with only one tool increases the efficiency of the lower blade guard housing 144 assembly process.

[0045] Next, to complete assembly of the lower blade guard housing 144, the mounting plate 188 is connected to the upper blade guard 140 with the fastener 264 and the fastener 266.

[0046] In another embodiment the fastening system 148 is included with a miter saw or any other type of power saw.

[0047] While the disclosure has been illustrated and described in detail in the drawings and foregoing description, the same should be considered as illustrative and not restrictive in character. It is understood that only the preferred embodiments have been presented and that all changes, modifications and further applications that come within the spirit of the disclosure are desired to be protected.