BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an exploded view of an implementation of a cutterhead including an adjustable knife.
FIG. 2 is a cross-sectional view of the cutterhead of FIG. 1 taken along line 2-2 of FIG. 4.
FIG. 3 is an enlarged view of FIG. 2.
FIG. 4 is a perspective view of the cutterhead of FIG. 1.
DETAILED DESCRIPTION OF THE DRAWINGS
Referring to FIGS. 1-4, in an implementation, a cutterhead 100 may be used in a power tool, such as a stationary jointer, a planer, a portable hand planer, a shaper (such as for forming molding), and the like. For example, the cutterhead 100 may be constructed for utilization in a 6″ (six inch) jointer or an 8″ (eight inch) jointer or even wider sizes, like 12″, 16″ or 20″. Additionally, the cutterhead 100 may allow for retrofitting into existing jointers, planers, molders, shapers and the like. For instance, a drive gear, a chain sprocket, and/or a belt pulley may be included on or mounted to the cutterhead 100 for rotating the cutterhead 100.
The cutterhead 100 includes a generally cylindrical main body portion 102 that defines one or more knife recesses 104 that extend longitudinally along the main body portion 102 between a first end 103 and a second end 105 of a main body portion 102. Each knife recess 104 is configured to receive a knife assembly 116 that includes a including a lockbar 118 and a knife 106. When multiple knife assemblies 116 are utilized, the knife recesses 104 are positioned in order to balance the cutterhead 100. For example, if three knife assemblies 116 are used, as shown in FIG. 1, the knife recesses 104 are spaced from one another at approximately 120° (one hundred twenty degrees), which helps minimize vibration and provide a smooth finish to the work surface.
Referring in particular to FIGS. 2 and 3, each knife recess 104 has a main portion 130 and a secondary portion 140. Secondary recess 140 is formed as a notch in a floor 134 of main portion 130. Main portion 130 has a generally trapezoidal cross-section defined by the floor 134, a first side wall 132 that is substantially perpendicular to floor 134, and a second, angled side wall 108. Side wall 108 is at an acute angle relative to floor 134 such that the width W1 of the recess 104 at the floor 134 is greater than the width W2 of the recess 104 at the opening of the recess 104. As described below, this angled side wall 108 facilitates holding a received knife assembly 118 and knife 106 at a desired orientation for material removal.
Referring to FIGS. 1-3, lock bar 118 of knife assembly 116 secures the removable knife 106 in the knife recess 104 by sandwiching the knife 106 against the angled sidewall 108 of the recess 104. Lock bar 118 has a substantially trapezoidal cross-section that corresponds generally to the cross-sectional shape of recess 104. Lock bar 118 includes a side 120 that is angled to correspond to the angled sidewall 108 of the knife recess. Thus, the knife 106 may be sandwiched or secured between the angled sidewall 108 of the knife recess and the angled side 120 of the lock bar. The angled side 108 of the knife recess 104 is directed so that rotation of the cutterhead forces the knife against the angled portion of the recess when the cutterhead 100 is rotated, e.g., via centripetal force, to provide an additional mechanism for holding the knife 106 firmly in place. The lock bar 118 and knife recess 104 also are dimensioned so that a user may remove the knife 106 and/or lock bar 118 from the recess 104 without having to pull the lock bar 118 out in the direction of the primary axis X. Thus, when implemented with a stationary jointer the lock bar may be efficiently removed from above the cutterhead (though a slot included between off-set support surfaces).
Referring to FIG. 2, the knife 106 is secured in the cutterhead 100 so that the knife is set at an acute positioning angle Θ between the surface 108 and a diameter D1 of body 102 that is parallel with the surface 132 and passes through the geometric center C of the cross-section of body 102. The knife 106 also is set at an acute cutting angle α relative to a diameter D2 of body 102 that extends through the tip of knife 106 and that passes through the geometric center C of the cross-section of body 102. The positioning angle Θ may be, for example, between approximately 10° and approximately 15°, so that centripetal forces help hold the knife 106 in place in recess 104. The cutting angle α may be chosen, e.g., based on the type of material of the workpiece, such as hardwood (e.g., oak, maple, walnut) or soft wood (e.g., pine), or may have an intermediate value to allow the user to implement the device for the widest range of materials. In certain implementations, the cutting angle α may be between approximately 25° and approximately 35°, for example, between approximately 27° and approximately 34°.
Referring to FIGS. 1 and 3, knife 106 and lock bar 118 define a series of apertures 150 and 152 (e.g., three apertures each), respectively, each of which are dimensioned to receive an index pin 122 to align the knife 106 with respect to the lock bar 118. Index pin 122 interconnects the knife 106 and lock bar 118 such that height adjustment of the lock bar 118 raises and lowers the knife 106 with respect to the outer cylindrical surface of the main body portion 102. In addition, index pins 122 may aid in maintaining proper alignment as centripetal force acts on the knife when the cutterhead is rotated. The knife apertures 150 are elongated (e.g., oval, a through channel, a key hole shaped, or the like) such that the position of the knife 106 along axis X may be adjusted. In an alternative embodiment, the lock bar apertures 152 may instead be elongated. If a knife is nicked, e.g., by a nail or other hard object, the knife may be adjusted along axis X so that corresponding nicks in other knives may be misaligned to allow for longer cutting life. In one implementation, the apertures 150 in knife 106 allow approximately a one-eighth of an inch offset, which may be sufficient for most typically encountered nicks.
The knife 106 and lock bar 118 are secured in place relative to the main body 102 by one or more securing screws 126, each of which pass through a threaded aperture 154 in main body 102 and aligned with index pin 122. Securing screws 126 engage the pin 122 in the lock bar 118, thus securing the knife 106 and lock bar 118 to the main body 102. In the present example, the securing screws drive the lock bar against the angled sidewall 108 of the recess 104. This securing system provides an additional mechanism to the angled side 108 for holding the knife assembly 116 in place, and also allows for height adjustment, as discussed below.
Referring to FIGS. 1 and 4, the knife assembly 116 includes one or more height adjustment members, e.g., set screws 124 received in threaded holes 158 in lock bar 118. Set screws 124 are used to adjust the height of the lock bar 118 and knife 106 relative to the main body 102. In one implementation, two height adjustment screws 124 are utilized in order to adjust the height evenly along the lock bar 118 and knife 106. By utilizing a height adjustment screw which is threaded through the lock bar 118 a user does not have to re-adjust the height every time a knife is changed. For example, a user may remove the knife by loosening securing screws 126 without having to remove or adjust the height adjustment screws 122. When a new knife is re-inserted, the new knife will register with pins 122 and will not need to be recalibrated in height with adjacent knives.
Referring to FIG. 1, the knife 106 includes an upper blade 107 and a lower blade 109 that allows the knife 106 to be inverted should one of the blades become unusable, e.g., due to damage. The knife 106 may be disposable to avoid the need for sharpening. In alternative embodiments, the knife may have a single blade and/or the blade(s) of the knife may be able to be sharpened.
Referring to FIGS. 1 and 4, extending from first end 103 of main body 104, along primary axis X of the cutterhead 100, is a primary shaft 110. In an implementation, the primary shaft 110 includes an alignment portion, e.g., in the form of a keyway 112 for securing the cutterhead to a drive mechanism, e.g., the power tool's drive mechanism such as a pocket for receiving the primary axis 110 in a stationary joiner. Extending from second end 105 of main body 104, along primary axis X, is a secondary shaft 114, for maintaining alignment of the cutterhead and minimizing vibration during use. For example, the secondary shaft 114 is received in a pocket or recess of the power tool.
Numerous modifications may be made to the exemplary implementations described above. For example, the cutterhead may have different numbers and orientations of recesses, lock bars, knives, blades, set screws, adjusting screws, locking pins, and apertures. The knife blade may have a single cutting edge and may be constructed to be re-sharpened. The apertures in the knife blade may extend completely or only partially through the knife blade. The alignment portion of the primary shaft may be flattened portion, an alignment aperture, or another type of a mechanical interlock. The index pin may be unitary with the lock bar or secured to the lock bar (e.g. threaded into engagement with the lock bar), e.g., to prevent loss. At least a portion of the securing screw may be received in an aperture or recess included in the lock bar. Various other types of securing mechanisms may be utilized. Additional types and numbers of height adjustment mechanisms may be used. These and other implementations are within the scope of the following claims.
Patent Application
20080066829
