Patent Publication Number: US-2022219343-A1

Title: Hair clippers with flexing electrically adjustable blades

Description:
RELATED APPLICATIONS 
     This application is a continuation-in-part of application Ser. No. 16/547,535, filed on Aug. 21, 2019, which &#39;535 application is a continuation of application Ser. No. 15/677,018, filed Aug. 15, 2017, now U.S. Pat. No. 10,391,646 B2 issued Aug. 27, 2019, which &#39;018 application is a continuation of application Ser. No. 14/622,554 filed Feb. 13, 2015, now U.S. Pat. No. 9,731,424 issued Aug. 15, 2017, which &#39;554 application is a continuation-in-part of application Ser. No. 13/727,274, filed on Dec. 26, 2012, now U.S. Pat. No. 9,352,476 issued May 31, 2016, which &#39;274 application is a divisional of application Ser. No. 12/592,537, filed on Nov. 24, 2009, now U.S. Pat. No. 8,341,846 issued Jan. 1, 2013, which &#39;018, &#39;554, &#39;274 and &#39;537 applications are incorporated by reference herein. Applicant claims priority under 35 U.S.C. § 120 therefrom. Application Ser. No. 12/592,537 is based upon provisional application Ser. No. 61/117,434 filed Nov. 24, 2008, which application is also incorporated by reference herein. Applicant claims priority under 35 USC§ 119(e) therefrom. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to hair cutting. 
     BACKGROUND OF THE INVENTION 
     Electrically operated hair clippers have been used for many years. Some of the commonly available models have a manual lever on the side to incrementally adjust the relative position between the stationary and the reciprocating blades in a blade set to adjust the minimum length of hair that is being clipped. Other prior art patents show infinite adjustability over a range. The prior art does not reveal motor-powered continuous adjustability of the blade set which affords the barber the ability to perform the adjustment even during the clipping activity by simply activating a switch and/or having a flexing compliance blade set that adjusts around the contours of the scalp of a flex clipper is described which, in addition to the aforementioned powered hair cutting length adjustment feature, provides an additional feature to help the cutting blade set float more effortlessly by adjusting automatically to the contours of a client&#39;s head, to prevent the blade set getting stuck and causing cuts and irritation to the scalp of the customer. 
     OBJECTS OF THE INVENTION 
     It is therefore an object of the present invention to provide a flexing hair clipper with a flexing cutting blade adjuster which adjusts automatically to the contours of a client&#39;s head to prevent the blade set getting stuck and causing cuts and irritation to the scalp. 
     It is also an object of the present invention to provide a hair clippers device with infinitely variable blade distances from the scalp of the patron. 
     Other objects which become apparent from the following description of the present invention. 
     SUMMARY OF THE INVENTION 
     The hair clippers of this invention use a self-contained motor-driven adjustment mechanism to adjust the relative position of the stationary and reciprocating blades of a common type of blade set, preferably with a flexing blade set to adjust to the contours of the scalp of the customer having his or her hair being cut and trimmed. 
     While other on/off switches can be used, preferably two momentary switches operable by the thumb of the hand holding the clipper afford a barber total automatic adjustment with the clipper itself in an on or off condition. There is no need for two-handed fidgeting or selection of only a few discrete increments of length adjustment as with the commonly available models. Since the small gear motors used for the adjustment are brush type or brushless permanent magnet motors which are operated by direct current, the adjustment feature is most compatible with cordless clippers already using an on-board DC source in the form of a re-chargeable battery to drive the reciprocating blade. The invention will be described as a modification of a cordless clipper, although AC driven corded type clippers can also be modified with this feature by the addition of an on-board AC to DC power supply for the adjustment motor. 
     In the first embodiment, a modified blade set is used such that a gear rack is attached to the stationary blade. It is engaged with a worm gear pinion driven by a low-speed gear motor through a reversible drive circuit. Either limit switches, limit sensors, or over-current sensors are used to disable the adjustment motor at either the long or short hair end limits. The motor then can only be driven in the opposite direction. 
     In the second embodiment, a conventional blade set is used. The modification is such that a motor-driven final gear replaces the manual handle thereby retaining the original mechanism (of any type) that is used to move the stationary blade relative to the reciprocating blade in the conventional blade set. A timing belt bushing couples a rear mounted adjustment motor to a front side-mounted gear train coupled to the shaft of the blade shifting mechanism. Attached to the timing belt bushing for linear back and forth excursions is a magnet with a pointer. The magnet is used to operate two normally closed magnetic reed switches placed at the opposite distal ends of the permissible excursion thereby serving the limit switch function. The pointer moves over a tri-colored linear scale viewable by the barber from the top of the hair clipper; this quickly indicates the hair length setting. A plastic housing cover over the adjustment motor at the back and over the timing belt bushing and gear train at the side encloses the entire compact mechanism. 
     In a third embodiment, a flex clipper is described which, in addition to the aforementioned powered hair cutting length adjustment feature, provides an additional feature to help the cutting blade set float more effortlessly, by adjusting automatically to the contours of a client&#39;s head to prevent getting stuck and causing cuts and irritation to the scalp. 
     To achieve this automatic adjustment, the blade set with motor driven length adjuster in now housed in a separate module. Compliance is introduced between this module and the main housing of the flex clipper. The blade set can now tilt a small amount in any direction to automatically adjust to the local scalp contours while the cutting process is controlled as usual by grasping the main housing. The rigid attachment of the blade set to the housing is replaced by a flexing compliant attachment. Two methods are described, one is by using a large diameter short bellows while the other method uses a short length (a ring) of thick-walled elastomeric foam tubing which provides similar function. 
     Both flexing compliant attachments permit tilting and a small amount of linear axial movement between blade set and main housing, but both resist any relative rotational movement between blade set and main housing. This rotational resistance ensures good control of the blade set by keeping the cutting edge always aligned with the top surface of the housing (as in a normal rigid attachment) except for any minor local tilting. This rotational stiffness must also resist the driving torque of the motor driving the reciprocating cutter blade. 
     Since the drive motor for the reciprocating cutter blade is in the main housing and the crank mechanism and blade set are in a separate module, a flexing compliant motor coupling that can follow any blade movements relative to the main housing is required. A metal bellows coupling of a diameter which fits inside the hollow interior of coupling bellows or foam ring is used. To keep the mass and size of the forward blade set module low, a modified cutting length adjuster mechanism is used; for example, in one embodiment, it uses a miniature stepper motor with a lead screw. The powering and control cable from the stepper motor driver in the main housing is also guided through the hollow interior of the coupling member. 
     The flexing compliance (i.e., spring characteristics) of the coupling member as well as the damping characteristics can be determined by the geometric design and material selected. The proper “feel” can be achieved through simulation and actual prototype testing known to those skilled in the art of hair clippers technology. While the damping characteristics are not as important as the compliance, they determine the smoothness and sound deadening performance. For the bellows, a wide variety of thermoplastic elastomers (TPE&#39;s) or rubbers can be used. By using thin material crossection, even normally rigid plastics such as nylons or polypropylene can be used. Geometric design of the bellows includes overall length and diameter as well as number and shape of convolutions. By using filled TPE&#39;s or alloys of rubber/TPE a wide variety of damping characteristics can be designed in. Foamed rubbers or TPE&#39;s can be used for a foam ring coupling; other parameters that can be selected include type of cell (open or closed) and size of the cells. Material selection must also pay attention to longevity and compatibility with lubricants and hair conditioners. 
     In a further alternate embodiment, the blade set is also capable of flexing around the contours of the customer&#39;s hair, scalp and skull. Power is applied to the blade set by a conventional motor within the handset housing of the clippers. The motor may be activated by conventional tap switches, rotating wheel switches, or other manually activated switches. Instead of a flexible cylindrical neck, as in the aforementioned flexing embodiment, in this embodiment, the blade set is pivotable upward from a first position to a second position, whereby the blade set is controlled by a semi-rigid flexible belt bushing piece, i.e. known as a “flexor” which is positioned on the bottom of the clippers housing and which includes a semi-rigid flexible curved distal end which biases against a portion of the blade set to urge the blade set to move around the contours of the customer&#39;s hair, scalp and skull during the process of a hair cutting. The flexor counteracts the propensity of the upwardly pivoted blade set to pivot outwardly and holds the blade set in a mid-point position so that the blade set can push in or push out while moving over the three-dimensional curvature of the hair, scalp and skull of the customer. The flexor gently pushes the pivoted blade set to a flexing motion or a relaxed motion against the hair, scalp and skull of the customer. The moving blade of the blade set moves horizontally against the stationery blade of the blade set during the cutting of the hair. A spring is provided to hold the movable blade and the stationery blade closely adjacent and parallel to each other. The spring is located under a driver which has a driver bracket attached to the blade set. The driver moves the movable blade against the stationery blade to facilitate cutting of the hair on the scalp and skull of the customer. The movable blade is moved closely adjacent and parallel to the stationery blade, by an eccentric rotating cam which is powered by the motor (such as for example the motor M in the other embodiment shown in drawing  FIG. 8 ) inside the housing of the hair clippers. The eccentric cam causes the driver to move the movable blade of the blade set adjacent to the stationery blade in subsequent left and right sets of multiple parallel movements, during cutting of the hair of the scalp and skull of the customer. The rod of the rotating cam is positioned between an open U-shaped driver and causes the movement of the movable blade against the adjacent surface of the stationery blade. The U-shaped driver is mounted to a driver bracket which is attached to the blade set, and urges the blade set forward or back in an infinitely variable range of motion, limited by the pushing or release of the flexor against the pivoted blade set. A pivot mount is attached to a pivot plate which pivots the blade set and pivots about a pin, which connects the movable pivot plate and blade set to the stationery pivot mount, which is mounted to a base. The base is preferably connected to a three-sided shroud which covers the two sides and front of the pivoting mechanisms in front of the pivotable blade set. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention can best be understood in connection with the accompanying drawings. It is noted that the invention is not limited to the precise embodiments shown in drawings, in which: 
         FIG. 1  is a perspective view of a typical prior art hair clipper with manual adjustment lever at the side. 
         FIG. 2  is a side elevation of the prior art hair clippers of  FIG. 1 . 
         FIG. 3  is a side elevation of a motor-driven mechanism for adjusting the stationary blade of a clipper blade set showing a rack and worm gear pinion of the first embodiment. 
         FIG. 4  is a perspective view of the hair clipper of this invention incorporating the mechanism of  FIG. 3 . 
         FIG. 4A  is a side view in crossection of the hair clipper of this invention, showing the primary motor therein. 
         FIG. 5  is a wiring diagram of the adjustment motor using an “H-bridge” type of reversible driver. 
         FIG. 6  is a top view of a second embodiment hair clipper with motor-driven adjustment of this invention. 
         FIG. 7  is a side elevation of the second embodiment clipper with the housing cover removed to reveal the timing belt bushing and gear train mechanism. 
         FIG. 8  is a side exploded elevation of the flex clipper embodiment of this invention. 
         FIG. 9  is an assembled perspective view of the flex clipper of  FIG. 8 . 
         FIG. 10  is a side elevation of a compliant coupling between blade set module and main housing based on the use of an elastomeric foam ring. 
         FIG. 11  is a perspective view of an elastomeric foam ring. 
         FIG. 12  is a perspective view of the cutting length adjuster mechanism as attached to the adjustable comb plate. 
         FIG. 13  is a high-level schematic diagram of the electrical elements of the flex clipper of this invention. 
         FIG. 14  is a perspective view of an alternate embodiment for a hair clipper with a flexing pivoting blade set. 
         FIG. 15  is a side view thereof. 
         FIG. 16  is a front view thereof. 
         FIG. 17  is an exploded view of the motor, eccentric cam, driver, pivot set, and blade set thereof. 
         FIG. 18  is a close-up perspective view of the flexing bushing belt associated with the pivoting blade set. 
         FIG. 19A, 19  B,  19 C,  19 D are top, perspective, side and end views of the driver bracket. 
         FIGS. 20A, 20B, 20C, 20D  are top, perspective, side and end views of the pivot plate. 
         FIGS. 21A, 21B, 21C, 21D  are top, perspective, side and end views of the pivot mount. 
         FIGS. 22A, 22  B,  22 C,  22 D are top, perspective, side and end views of the driver. 
         FIGS. 23A, 23B, 23C, 23D  are top, perspective, side and end views of the inner cover/shroud. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIGS. 1 and 2  show two views of a conventional cordless electric hair clipper  1  with on/off switch  3 , conventional blade set  2 , and side manual incremental adjusting handle  4 . The detents  5  engage handle  4  to set the minimum hair cutting length at one of the selections. 
       FIG. 3  shows the mechanism which uses gear motor  10  driving worm gear pinion  11  to perform an adjustment of stationary blade  14  relative to reciprocating blade  13  in blade set  12 . A gear rack  15  subassembly is attached to blade  14  and engages pinion  11 . Also shown in this view are limit switches  16  and  17  at the longest and shortest settings respectively.  FIGS. 4 and 4A  show clipper housing  20  with the adjustment feature. Conventional on/off switch  25  connected to clipper motor  24  (shown schematically as an encircled “M”) is at one side while momentary (or “tap”) switches  21  and  22  on the top surface are used to energize gearmotor  10  in a direction toward longer settings or shorter settings respectively. Gearmotor  10  is enclosed in descending housing  26 , which descends below clipper housing  20 . While  FIGS. 3, 4 and 4A  show a worm gear, it is anticipated that other gears may be used, such as rack and pinion gears or other gears known to those skilled in the art. 
       FIG. 5  is a wiring diagram for the first embodiment of  FIGS. 3 and 4  wherein gearmotor  10  is a simple brush type permanent magnet type driven by a common “H-bridge” drive module  35 . Battery  30  is used primarily to power clipper motor  24  through on/off switch  25 . It is also used as the power source for the adjustment feature. Drive module  35  has two direction inputs for clockwise and counterclockwise operation, an “ON” input, and power input and motor output connections as shown. In operation, if normally open switch  22  is pushed, a signal will flow through normally closed limit switch  17  energizing the ON input through isolation diode  36 ; motor  10  will be driven clockwise until either switch  22  is released or limit switch  17  is opened at the end of the excursion. Similarly, if switch  21  is pushed, counterclockwise operation is achieved through limit switch  16  and isolation diode  37 . Once a limit switch is opened, motor  10  can only be driven in the opposite direction until the open limit switch is again closed. 
       FIGS. 6 and 7  show top and side views of the second embodiment of motor-driven minimum hair length adjustable hair clippers. The same circuit shown in  FIG. 5  is completely applicable to this embodiment as well. The same momentary (“tap”) switches  21  and  22  are used to control motor  10  which is now placed at the back end of hair clipper  40 . Except for the addition of switches  21  and  22 , the housing  41  and internal mechanism is identical to that of the prior art cordless clipper shown in  FIGS. 1 and 2 . In this embodiment, a conventional blade set  12  and internal blade adjusting mechanism is used. The feature of this embodiment couples through the shaft formerly engaged with a manual handle  4 . This is shown at the center of output gear  51 . In the top view of  FIG. 6 , housing cover  42  is a plastic shell used to enclose the feature mechanism. In  FIG. 7 , this cover  42  is removed to reveal the mechanism; the position is shown in dashed lines. On the top edge of cover  42  is a tri-colored strip  43  with green region  45  denoting the long settings, yellow region  46  denoting medium length settings, and red region  47  denoting short settings. This scale is meant to be read relative to the position of pointer assembly  44  which is attached to timing belt bushing  55  transmitting power and torque from pulley  57  mounted on motor  10  to pulley  56  attached to the input gear of gear train  50 . 
     Gear train  50  is used to adjust the torque at output gear  51  and to match the speed and torque of gear motor  10  and the desired indicating excursion of belt bushing  55  so as to form an ergonomic range. Besides the pointer on top, pointer assembly  44  also carries a small powerful magnet to operate limit switches  16  and  17  which are now implemented as normally closed magnetic reed switches. On/off switch  25  fits between timing belt bushing  55  and pokes through a side switch hole in housing cover  42 . While  FIGS. 6 and 7  show a particular embodiment for an exterior mounted embodiment, it is anticipated that other exterior mounted embodiments may be used, such as those known to those skilled in the art. 
     While this third embodiment will be described as for a flex hair clipper with both powered hair cutting length adjustment as well as flexing compliance introduced between the main housing and blade set module, it should be noted that the flexing compliance feature to permit the blade set to automatically adjust to scalp contours and irregularities can be afforded to hair clippers without the powered hair cutting length adjustment. If the latter feature is not implemented, the blade set module will just contain the blade set and crank mechanism with coupling to the drive motor in the main housing which operates the reciprocating cutting blade; there would not be a cutting length adjustor motor, adjuster mechanism attached to the comb plate, nor a housing for the adjuster motor. 
       FIG. 8  shows an exploded view of the major components of this embodiment. Flex clipper  100  has main housing  110  which contains drive motor  116  with shaft  112  which drives the reciprocating cutter blade  113 , rechargeable battery  135  (unless it is an AC driven corded model), and an electronic driver module  160  for the hair cutting length adjuster motor  145  located in blade set module  140  at the left of the  FIG. 8 . Rigid coupling ring  118  is attached at the coupling end of housing  110 . Blade set module  140  carries adjustable comb plate  114 , reciprocating cutter blade  113 , internal crank mechanism  143  for reciprocating cutter blade  113 , drive shaft  142  for crank mechanism  143 , housing  144  for internal hair length adjustment motor  145 , internal hair length adjustment direct comb plate mechanism  114  (shown in  FIG. 12 ), and a rigid coupling ring  146 . 
     Also shown in  FIG. 8  is molded compliant bellows  120  with integral mounting rings  126  and  128  is shown between blade module  140  and main housing  110 , which it couples together. Metal bellows  130  couples drive motor  116  in main housing  110  and crank drive shaft  142  in blade module  140 . Cable  148  powers and controls motor  145  for hair cutting length adjustment from electronic step driver module  160  contained in housing  144 ; it is passed through the hollow interior of bellows  120 . 
       FIG. 9  shows an assembled flex clipper  100  showing tap switches  21  and  22  for adjusting cutting length and clipper operating switch  25 . A thumb operable reverse direction wheel  23  can also be optionally used. Bellows  120  is shown coupling blade module  140  to housing  110  in a flexing compliant fashion. The length of bellows  120  as shown in  FIGS. 8 and 9  may be shorter than shown based on the design and materials of the bellows. Bellows integral collars  126  and  120  fit over fixed collars  146  and  118  on blade module  140  and housing  110  respectively. Fasteners, such as self tapping screws, are used to secure the bellows collars to collars  146  and  118  which preferably have transverse holes in registration. 
       FIG. 10  shows an alternate embodiment of an assembly of resilient foam ring  152  with attached metal collars  154 , which are adhesively attached or vulcanized as appropriate to the collar material. The assembly of  FIG. 10  can be used in lieu of custom molded bellows  120 . Depending on many variables known to those skilled in the hair clippers technology, such as desirable product life, product price point, manufacturing cost, performance, volume, and materials used, either the bellows or the foam ring assembly may be the better choice. 
       FIG. 11  shows a perspective view of the foam ring prior to attachment of coupling rings  154 . 
     Although other types of flexing compliant motor couplings can be used, such as a variety of spring type couplings, the preferred coupling between shaft  112  and shaft  142  for reciprocating blade drive is a metal bellows coupling  130  such as those supplied by Servometer of Cedar Grove, N.J. This type of coupling easily fits inside the hollow bellows  120  or foam ring  152  central hole while not interfering with the degrees of freedom of the bellows or foam ring. 
       FIG. 12  shows the simple direct comb plate  114  adjustment mechanism which includes preferably stepper motor  145 , and a fastening mechanism, such as, for example, threaded bracket  149  and fine lead screw  147 . Although other methods can be incorporated, a stepper motor  145  is preferred to a DC gearmotor due to size and complexity. At about 6 mm diameter and 9.5 mm long, a FDM0620 stepper motor from Micromo of Clearwater, Fla. is very compact and is driven with 20 steps per revolution to drive lead screw  147 . 
       FIG. 13  shows a schematic diagram for the flex clipper. It is noted that no limit switches are required because step motors can just “lose steps” with no damage when a hard stop is encountered. Tap switches  22  and  24  determine the direction of rotation of stepper motor  145  by supplying the proper sequence of steps from step driver module  160  over cable  148 . Reciprocating blade motor  116  for reciprocating cutter blade  113  is directly powered through switch  25 . Battery  135  (or equivalent DC power supply for corded versions) supplies power to both reciprocating blade motor  116 , and to stepper motor  145 , through step driver module  160 . 
       FIGS. 14-23D  show a further flexing hair clipper  200 . In a further alternate embodiment, the blade set  206 ,  207  is also capable of flexing around the contours of the customer&#39;s hair, scalp and skull. Power is applied to the blade set  206 ,  207  by a conventional motor M (as in  FIG. 17 ) within the handset housing  208  of the hair clippers  200 . The motor M may be activated by conventional tap switches, rotating wheel switches, or other manually activated switches (not shown). Instead of a flexible cylindrical neck, as in the aforementioned flexing embodiment of  FIGS. 8-13 , in this embodiment, in  FIGS. 14-23D , the blade set  206 ,  207  is pivotable upward from a first position to a second position, whereby, as shown in  FIG. 18 , the blade set  206 ,  207  is controlled by a semi-rigid flexible belt bushing piece  215 , i.e. known as a “flexor”  215  which is positioned on the bottom of the clippers housing  208 . The flexor  215  includes from top to bottom a series of joined, parallel rippled wave-like rounded peaks  215   c  and valleys  215   d . The flexor  215  includes a semi-rigid flexible curved distal end  215   a , attached to a linear proximal body portion  215   b . The semi-rigid flexible curved distal end  215   a  biases against a portion of the blade set  206 ,  207  to urge the blade set  206 ,  207  to move around the contours of the customer&#39;s hair, scalp and skull during the process of a hair cutting. The flexor  215  counteracts the propensity of the upwardly pivoted blade set  206 ,  207  to pivot outwardly and holds the blade set  206 ,  207  in a mid-point position so that the blade set  206 ,  207  can push in or push out while moving over the three-dimensional curvature of the hair, scalp and skull of the customer. The semi-rigid flexible curved distal end  215   a  of the flexor  215  gently pushes the pivoted blade set  206 ,  207  to a flexing motion or a relaxed motion against the hair, scalp and skull of the customer. The straight linear proximal body portion  215  of the flexor  215  stabilizes the flexor  215  against the body of the hair clipper  200 . 
     The moving blade  206  of the blade set  206 ,  207  moves horizontally against the stationery blade  207  of the blade set  206 ,  207  during the cutting of the hair. A spring (not shown) is provided to hold the movable blade  206  and the stationery blade  207  closely adjacent and parallel to each other. The spring is located under a driver  204  which has a driver bracket  201  attached to the blade set  206 ,  207 . The driver  204  is connected to the driver bracket  201 , which pivots about driver pin  210  by the force of driver  204 . The driver  204  moves the movable blade  206  against the stationery blade  207  to facilitate cutting of the hair on the scalp and skull of the customer. The movable blade  206  is moved closely adjacent and parallel to the stationery blade  207 , by an eccentric rotating cam  211  which is powered by the motor M (such as for example the motor M in the other embodiment shown in drawing  FIG. 8 ) inside the housing  208  of the hair clippers  200 . Motor “M” is powered by a power source being one of a battery within the main hair clipper housing  208  or an AC driven corded power source, similar to battery  135  of  FIG. 8  herein, (or equivalent DC power supply for corded versions) which supplies power to both reciprocating blade motor “M”, or, as also shown in  FIG. 8 , to a stepper motor  145 , through a step driver module  160 . 
     The eccentric cam  211  causes the driver  204  to move the movable blade  206  of the blade set  206 ,  207  adjacent to the stationery blade  207  in subsequent left and right sets of multiple parallel movements, during cutting of the hair of the scalp and skull of the customer. The rod  211   a  of the rotating eccentric cam  211  is positioned between the open U-shaped driver  204  and causes the movement of the movable blade  206  against the adjacent surface of the stationery blade  207 . 
     The U-shaped driver  204  is mounted to a driver bracket  201  which is attached to the blade set  206 ,  207 , and urges the blade set  206 ,  207  forward or back in an infinitely variable range of motion, limited by the pushing or release of the bushing belt flexor  215  against the pivoted blade set  206 ,  207 . A pivot mount  202  is attached to a pivot plate  205  which pivots the blade set  206 ,  207  and pivots about a pin  209 , which connects the movable pivot plate  205  and blade set  206 ,  207  to the stationery pivot mount  202 , which is mounted to a base. The base housing  208 , supports motor “M” within, and the base housing  208 , is preferably connected to a three-sided shroud/cover  203 , which covers the two sides and front of the pivoting mechanisms in front of the pivotable blade set  206 ,  207 . 
     In the foregoing description, certain terms and visual depictions are used to illustrate the preferred embodiment. However, no unnecessary limitations are to be construed by the terms used or illustrations depicted, beyond what is shown in the prior art, since the terms and illustrations are exemplary only, and are not meant to limit the scope of the present invention. 
     It is further known that other modifications may be made to the present invention, without departing the scope of the invention, as noted in the appended Claims.