Abstract:
A portable mixing device for quickly and efficiently combining dry constituents with water to form a mix having a thin batter consistency and no unmixed material. Mounted on a wheeled, pivoting frame, a single individual can use the device to mix the material and pour it in the proper location. The device includes a cylindrical mixing drum and agitation tool mounted within the mixing drum. The agitation tool includes a motor and housing, a drive shaft, wiping assembly, and mixing assembly. The stationary wiping assembly, which extends downward into the mixing drum co-mingles so as to pass closely between and among the blades of the rotating mixing assembly such that the flexible edge portions of the wiping assembly blades are in intermittent contact with the blades of the mixing assembly. The “wiping” action of the wiper assembly on the mixing assembly insures complete and efficient agitation and mix of materials.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    This invention is directed to an inventive mixing device. Specifically, this invention is directed to a mixing device for combining dry constituents with water to form a cement. More specifically, this invention is directed to a portable device for mixing gypsum cement with water to form a thin slurry where the device is operable and transportable by a single individual.  
           [0002]    A variety of cementious materials are used in the construction industry. A segment of these materials consist of cements formed from very thin slurries. These materials are so thin in comparison to the relatively thick and stiff common cements, grouts, and mortars, that they require specialized equipment and handling techniques to implement. These thin materials are generally transported to a job site in a large truck, and transferred to the work area by pumping through hoses. Because of the need for large and extensive specialized equipment, and the great number of workers required to operate the equipment, the economic cost of implementing the thin cementious material has prevented it from being used in small-scale construction applications.  
           [0003]    An example of the thin cementious material is a specialized gypsum cement commercially known as “Gypcrete”. These materials are currently used as self-leveling underlayment cements for leveling floors, as a thermal mass for radiant heat flooring, for acoustic insulation and as a flooring fire retardant. If these products were more portable, excellent results could be found transferring commercial-scale applications to small-scale jobs. Additionally, a portable mixing device would allow use of gypsum cements in jobs having limited access. For instance a portable mixing device could be used in upper stories of a high rise building. In urban areas, where parking and traffic make use of big equipment difficult and expensive, a portable mixing device would provide an economical and logistical solution.  
         SUMMARY OF THE INVENTION  
         [0004]    The inventive portable mixing device allows quick and efficient combination of dry constituents with water to form a mix having a thin batter consistency, no lumps, and no unmixed material. Mounted on a wheeled, pivoting frame, a single individual can use the portable mixing device to mix the material and pour it in the proper location. In this way, the possible applications of this material are greatly expanded, since the material can now be used in a greater variety of applications and for smaller scale projects.  
           [0005]    The inventive portable mixing device includes a cylindrical mixing drum which houses an agitation tool and which is mounted to a pivoting, wheeled frame. The agitation tool includes a motor and housing, a drive shaft, wiping assembly, and mixing assembly. The stationary wiping assembly, which extends downward into the mixing drum comingles so as to pass closely between and among the blades of the rotating mixing assembly such that the flexible edge portions of the wiping assembly blades are in intermittent contact with the blades of the mixing assembly. The “wiping” action of the wiper assembly on the mixing assembly insures complete and efficient agitation and mix of materials.  
           [0006]    The motor resides within a motor housing, and the motor housing is fixed to the frame so as to reside above the open top end of the mixing drum and so that the drive shaft extends from the motor downward into the mixing drum.  
           [0007]    The wiping assembly is made up of a set of elongate blades which are provided with flexible edge portions. The wiping assembly is stationary, being fixed to the motor mount and extending downward into the mid portion of the mixing drum so as to lie generally parallel with the drive shaft.  
           [0008]    The mixing assembly is made up of a second set of elongate blades which are fixed to and rotationally driven by the drive shaft. The blades of the mixing assembly extend generally vertically upward from the lower end of the mixing drum so as to pass closely between and among the blades of the wiping assembly. During operation, the flexible edge portions of the wiping assembly blades are in intermittent contact with the rotating blades of the mixing assembly. The flexible edge portions sweep across the surface of mixing blade to remove any accumulation of unmixed material therefrom thus greatly increasing the efficiency of agitation within the mixing drum.  
           [0009]    Because the mixing drum is vertically oriented during agitation, elements have been included which are designed to prevent dry components from settling to the bottom of the mixing drum and remaining unmixed. The first such element includes “L” shaped mixing assembly blades which are positioned adjacent to the mixing drum wall near the bottom of the mixing drum. These blades are mounted at an acute angle relative to the vertical so as to drive the mix upward to the mid portion of the drum during agitation. Additionally, the bottom edge of the “L” is radially aligned and extends radially from the drum wall toward the centerline of the mixing drum so as to co-mingle and interact with the second element.  
           [0010]    The second element which is designed to prevent dry components from settling to the bottom of the mixing drum and remaining unmixed are a pair of horizontally extending bars which are fixed to and are spaced to lie above the bottom surface of the mixing drum. These bars agitate material which is dislocated from resting on the bottom surface by the sweeping action of the bottom edge of the “L” shaped mixing assembly blades.  
           [0011]    The wheeled support frame of the inventive portable mixing device allows the mixing drum to selectively pivot between two positions. The first upright position is used during agitation of materials within the mixing drum. In this position, the longitudinal axis of the mixing drum is vertical and the top end of the mixing drum overlies its bottom end. The second tipped position is used to pour out the contents of the mixing drum. In the second position, the longitudinal axis of the mixing drum is no longer vertical and the top end of the mixing drum is positioned below the bottom end of the mixing drum. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    [0012]FIG. 1 is a perspective view of the portable mixing apparatus illustrating the mixing drum, the wheel-mounted support frame, and the top mounted agitation tool.  
         [0013]    [0013]FIG. 2 is an exploded view of the agitation means shown in relation to the rest plate and a side sectional illustration of the mixing drum.  
         [0014]    [0014]FIG. 3 is a side sectional view of the bearing mount and lower agitating bars at the lower end of the mixing drum.  
         [0015]    [0015]FIG. 4 is a side view of the portable mixing apparatus in an upright position with the tipped, pouring position overlying this view and shown in phantom.  
         [0016]    [0016]FIG. 5 is a horizontal sectional view of the wiper assembly illustrating the cooperative relationship between the wiper assembly and the mixing assembly.  
         [0017]    [0017]FIG. 6 is a bottom view of the portion of the support frame which supports the lower end of the mixing drum showing the square opening which receives the drive shaft bearing.  
         [0018]    [0018]FIG. 7 is a front sectional view of the portable mixing apparatus, showing the interrelationships of the wiper assembly and the mixing assembly and showing that the wiper assembly is suspended from the top of the cylindrical mixing container. 
     
    
     DETAILED DESCRIPTION  
       [0019]    The portable mixing device will now be described with reference to FIGS.  1 - 7 . As illustrated in FIG. 1, portable mixing device  10  consists of an inventive agitation tool  15  which is supported by a wheeled support frame  20 . Agitation tool  15  includes cylindrical mixing drum  100 , motor  200 , drive shaft  150 , wiping assembly  400 , and mixing assembly  500 .  
         [0020]    For the purpose of providing a clear description, portable mixing apparatus  10  will be described as having a front end  2  which corresponds to the leading end of the device as it is being pushed from behind, a rear end  4  which corresponds to the trailing end of the device as it is being pushed from behind, and right  6  and left  8  sides as seen from a rear view of the device.  
         [0021]    Frame  20  is a series of bars joined to form an open, transparent structure having a non-rotating external frame  25  and an internal frame  27  which is pivotable relative to external frame  25 . External frame  25  is provided with a generally rectangular, horizontally oriented, wheeled base to which are mounted several vertically oriented bars which form the superstructure which supports internal frame  27 .  
         [0022]    Internal frame  27  is generally cylindrical in shape, being formed of a series of rings or hoops  80 ,  82 ,  84  which are axially aligned and spaced and which are mutually parallel. Rings  80 ,  82 ,  84  are maintained in this axially aligned and spaced configuration by fixing rings  80 ,  82 ,  84  to a series of vertically oriented support bars  86 ,  88 ,  90 ,  92 . The resulting structure is cylindrically shaped and sized to receive the cylindrical mixing drum  100  within its hollow interior. Ring  80  is positioned at the lower end of internal frame  27 , ring  84  is positioned at the upper end of internal frame  27 , and ring  82  lies mid way between ring  80  and ring  84  to support the midsection of mixing drum  100 . When mixing drum  100  is placed within internal frame  27 , the open upper end  110  of mixing drum  100  is aligned with and surrounded by ring  84 , the closed lower end  112  of mixing drum  100  is aligned with and surrounded by ring  80 , and the longitudinal axis of mixing drum  100  is coincident with the longitudinal axis of internal frame  27 .  
         [0023]    Vertically oriented support bars  86 ,  88 ,  90 ,  92  are positioned about the circumference of internal frame  27 . Support bar  86 , located at the front  2  of internal frame  27 , and support bar  88 , located at the rear  4  of internal frame  27 , are thin, elongate rectangular plates which are fixed to upper ring  84  at one end, lower ring  80  at the opposite end, and to mid ring  82  at their midpoints. Support bar  90 , located at the right side  6  of internal frame  27 , and support bar  92 , located at the left side  8  of internal frame  27 , are elongate rods having square cross sections. Support bars  90 ,  92  have a length which is greater than the distance between upper ring  84  and lower ring  80  so that when support bars  90 ,  92  are fixed at one end to lower ring  80 , the respective opposite ends of support bars  90 ,  92  extend upward above upper ring  84 . Support bars  90 ,  92  are fixed to mid ring  82  and upper ring  84  at their respective intersections with these rings. The upper end  91  of support bar  90 , and the upper end  93  of support bar  92 , which extend upward above upper ring  84 , form mounting posts which receive sleeves  228 ,  230  of motor mount  220 .  
         [0024]    Referring now to FIG. 6, lower ring  80  is provided with four lower ring support bars  96  which extend radially inward from the lower edge of ring  80  to form a horizontal platform which supports closed lower end  112  of mixing drum  110 . Square loop  98  is a bracket which receives the square bearing housing  120  of drive shaft bearing  122 , and is fixed and supported in the horizontal plane by ring support bars  96 .  
         [0025]    The generally rectangular, horizontally oriented base of external frame  25  is constructed using elongate bars of square cross section. A pair of horizontally aligned, laterally spaced, parallel bars  40 ,  42  extend from the front  2  to rear  4  of portable mixing device  10 . As shown in FIG. 1, a pair of pivoting castor-type wheels  56  support the front  2  of the base. A pair of hubbed wheels  58  support the rear  4  of the base. In the preferred embodiment, wheels  58  are provided in a diameter which is about that of a stair riser. This wheel diameter allows easier handling on stairs.  
         [0026]    Lateral bars  40 ,  42  are joined at the rear end by perpendicular cross bar  60 . Perpendicular cross bar  44  joins lateral bars  40 ,  42  in their respective mid sections, and is parallel to perpendicular cross bar  60 . A pair of angled cross bars  54  extend from the respective front ends of lateral bars  40 ,  42  to the midpoint  45  of perpendicular cross bar  44  so as to form a “V” shaped vacancy at the front of the base of external frame  25 . This “V” shaped opening allows the mixed material to flow to the ground without interference with external frame  25  when internal frame  27  is pivoted to a pouring position (FIG. 4).  
         [0027]    Several vertically oriented bars form the superstructure which supports internal frame  27 . A first vertically upright bar extends upwards adjacent to the rear end of each respective lateral bar  40 ,  42 , resulting in a right side rear bar  21  and a left side rear bar  23 . Each respective rear bar  21 ,  23  has an upper end  22 ,  24 , a lower end  26  (only right side shown), and a mid portion  28  (only right side shown) which extends between the upper  22 ,  24  and lower  26  ends. Upper ends  22 ,  24  of each respective rear bar  21 ,  23  are angled toward the rear  4  to form handles for pushing and steering portable mixing device  10 .  
         [0028]    A second vertically upright bar extends upwards from the front end of each respective lateral bar  40 ,  42 , resulting in a right side front bar  48  and a left side front bar  46 . Each respective front bar  48 ,  46  has an upper end  62  (only right side shown), a lower end  50 ,  67 , and a mid portion  64 ,  66  which extends between the upper  62  and lower  50 ,  67  ends. Mid portion  64  of right side front bar  48  is angled so that the upper end  62  intercepts with and is fixed just below upper end  22  of right side rear bar  21 . Likewise, mid portion  66  of left side front bar  46  is angled so that the upper end (not shown) intercepts and is fixed just below upper end  24  of left side rear bar  23 .  
         [0029]    Pivot bearing  68  is mounted to an upper surface of each respective mid portion  64 ,  66 . Bearing  68  receives and pivotally supports bearing shaft  70 . A bearing shaft  70  extends radially outward from both the left and right side of mid ring  82 . Pivot bearings  68  and shafts  70  allow the internal frame  27 , and the mixing drum  100  contained therein, to rotate about a longitudinal axis of the shafts  70  between a first position and a second position.  
         [0030]    The first position is an upright orientation such that the longitudinal axis of the internal frame  27  is vertically aligned and upper ring  84  lies above and aligned with lower ring  80 . This is the position in which mix contents are added to mixing drum  100  and in which agitation of the contents occurs. The second position is a tipped orientation such that the longitudinal axis of the internal frame  27  lies at an acute angle to, and below, the horizontal, and upper ring  84  lies below lower ring  80 . This is the position in which the contents of mixing drum  100  are emptied by pouring into the desired area.  
         [0031]    Stop  74  is mounted to mid portion  64  of right side front bar  48  to prevent internal frame  27  from rotating beyond the second position. Stop  74  is an elongate post having a square cross section which extends inward from external frame  25  toward internal frame  27 . As internal frame  27  rotates about bearing shaft  70  relative to external frame  25  to the second position, internal frame  27  interferes with stop  74  and is prevented from over-rotation. Although illustrated in FIG. 7 as mounted to both right side front bar  48  and left side front bar  46 , it may alternatively be mounted to one side only.  
         [0032]    Frame  20  is provided with latch  30  which allows selective and releasable securement of internal frame  27  to external frame  35  in the first (upright) position. Latch  30  is an elongate thin plate having a first end  31 , a second end  32 , and a mid portion  33  which extends between the first end  31  and the second end  32 . Mid portion  33  is received within slot  29  formed in mid portion  28  of right side rear bar  21  such that first end  31  extends outwardly toward the rear  4  of mixing device  10  to form a handle for operating latch  30 . Latch pivot pin  35  is supported within mid portion  28  of right side rear bar  21  such that it passes through latch  30  and slot  29 , allowing latch  30  to pivot within slot  29  about a longitudinal axis of latch pivot pin  35 . Latch second end  32  is shaped to form a downwardly extending hook.  
         [0033]    Right side vertical support bar  90  of internal frame  27  is provided with laterally outward extending latch hook post  34 . In operation, latch second end  32  rests on latch hook post  34 , the downward extension of latch second end  32  residing on a front  2  surface of latch hook post  34  in order to prevent unwanted forward rotation of internal frame  27  relative to external frame  25 . Latch  30  may be disengaged from latch hook post  34  by applying downward pressure on latch first end  31 . Such downward pressure results in an upward pivot of latch second end  32  about latch pivot pin  35 , allowing second end  32  to be released from latch hook post  34 . Latch spring  38  extends from latch mid portion  33  to a lower portion of external frame  25 , and maintains latch  30  in engagement with latch hook post  34  unless downward pressure is applied to latch first end  31 .  
         [0034]    Agitation tool  15 , which includes cylindrical mixing drum  100 , motor  200 , drive shaft  150 , wiping assembly  400 , and mixing assembly  500 , will now be described with respect to FIG. 2.  
         [0035]    Mixing drum  100  is an elongate hollow cylinder, and is provided with a longitudinal axis  118 , an open upper end  110 , and a closed lower end  112 . Interior surface  116  of mixing drum  100  defines an interior space, and is opposed to mixing drum exterior surface  114 . Mixing drum is sized and shaped to reside within the interior of internal frame  27  such that longitudinal axis  118  coincides with the longitudinal axis of internal frame  27 , and such that the open upper end  110  is encircled by upper ring  84 .  
         [0036]    In the preferred embodiment, mixing drum  100  is sized to produce 2.5 cubic feet of mixed material. This volume of material is large enough to be time- and effort-efficient at a work site, and is also small enough to be handled by a single individual. It is, however, within the scope of the invention to provide mixing drum  100  of larger and/or smaller size, with appropriate scaling of the frame  20 , in order to meet the requirements of individual users.  
         [0037]    Motor  200  is mounted above mixing drum  100  such that its drive shaft  150  extends downward into mixing drum  100  along its longitudinal axis  118 . Motor  200  rests on and is fixed to motor mount  220 . Motor mount  220  consists of a thin elongate horizontal plate  224  which is trapezoidal in shape, the longer side edge  236  of the two parallel side edges extending from right to left across the diameter of internal frame  27 . Plate  224  is reinforced on its underside adjacent side edge  236  by an elongate angled-section rod  226  having a “L” shaped cross section. Rod  226  is fixed to the underside of plate  224  such that one leg  225  of rod  227  is horizontally oriented and abuts the underside of plate  224 . The remaining leg  227  of rod  226  is vertically disposed and lies normal to the underside of plate  224  to form a downwardly extending lip. Both side edge  236  and rod  226  are provided with semi-circular cut-away portion  234  at the center to allow drive shaft  150  to extend therethrough.  
         [0038]    The upper surface of horizontal plate  224  is provided with vertical shield  222  which extends upward perpendicular to plate  224  along shorter of the two parallel side edges and along the two adjacent remaining (non-parallel) side edges of the trapezoid. Vertical shield  222  forms a generally hemispherical screen between motor  200  and the rear  4  of portable mixing device  10 . Vertical shield  222  protects motor  200  from loose debris during filling of mixing drum  220 , which is done at the rear  4  upper end  110  of mixing drum  100  using rest plate  300 .  
         [0039]    Horizontal plate  224  of motor mount  220  is provided with a pair of elongate hollow sleeves  228 ,  230  which are square in section and have a closed upper end and open lower end. Sleeve  228  is positioned at the right side of plate  224  such that its outer wall is fixed to and abuts side edge  236  and the right end edge of vertical shield  222 . The open lower end of sleeve  228  is aligned with the lower surface of plate  224 . Sleeve  228  is sized to receive the upper end  91  of support bar  90  of internal frame  27  within its hollow interior. Sleeve  230  is positioned at the left side of plate  224  such that its outer wall is fixed to and abuts side edge  236  and the left end edge of vertical shield  222 . The open lower end of sleeve  230  is aligned with the lower surface of plate  224 . Sleeve  230  is sized to receive the upper end  93  of support bar  92  of internal frame  27  within its hollow interior.  
         [0040]    A horizontal channel  238  is formed in each sleeve  228 ,  230  adjacent to its lower end. When sleeves  228 ,  230  are mounted on support bars  90 ,  92 , channel  238  is in alignment with a horizontal channel (not shown) formed in each respective upper end  91 ,  93  of support bars  90 ,  92  to form a continuous through channel which extends completely through each sleeve  228 ,  230  and its respective support bar  90 ,  92 . Each respective through channel is sized to fittingly receive lock pin  232  therein. When lock pins  232  are in place within the respective through channels, motor mount  220  cannot be removed from the upper ends  91 ,  93  of support bars  90 ,  92 .  
         [0041]    Rest plate  300  is mounted to the upper edge of upper ring  84  and forms a horizontal surface on which bags containing dry mix materials can be rested while bag contents are let into mixing drum  100 . Rest plate  300  is generally rectangular in shape and has an upper surface  312  upon which bags are rested, and a lower surface  314  which is opposed to upper surface  312  and abuts upper ring  84 . Rest plate  300  overlies the rear half of open upper end  110  of mixing drum  100 , and extends horizontally rearward beyond the outer edge of upper ring  84 . The portion of rest plate  300  which overlies open upper end  110  is cut away to provide a large semicircular opening  318  through which the contents of the mix bags are passed. A ladder-shaped rack  320  extends horizontally across opening  318  to prevent mix bags from falling into mixing drum  100  or catching on moving parts.  
         [0042]    Rest plate  300  is reinforced on its lower surface  314  by an elongate flexible metal strip  310 . Rod  310  is bent into a curve along its length to form a semi-circle, and is welded to lower surface  300 . Rod  310  is vertically disposed and lies normal to lower surface  300  to form a rim. The semi-circular curve of rod  310  is sized such that the rim slides down into and is tightly received in the open space between the top edge of the open upper end  110  of mixing drum  100  and the top edge of upper ring  84 . In operation, mixing drum  100  is placed within internal frame  27 , rest plate  300  is placed over the open upper end  110  as described above, and then motor mount  220  is mounted to the upper ends  91 ,  93  of support bars  90 ,  92  of internal frame  27 , and is secured in place using pins  232 .  
         [0043]    Drive shaft  150  extends downward from motor  200  through drive shaft opening  115  in closed lower end  112  of mixing drum  100  and terminates in drive shaft bearing  122 . Drive shaft bearing  122  is mounted within square shaped bearing housing  120 , which is, in turn, fixed to the exterior surface  114  of the closed lower end  112  of mixing drum  100 . Wet and dry contents of mixing drum  100  are prevented from contaminating drive shaft bearing  122  by passing drive shaft  150  through a cylindrical bushing  132  which is lined with packing  134 . Preferably, packing  134  is comprised of cylindrical layers of square ropes stacked and alternated with rubber gaskets. It is within the scope of this invention, however, to use an alternative packing means. Cylindrical bushing  132  is fixed in longitudinal alignment with the drive shaft to the lower agitating assembly mount plate  130  which is in turn fixed to the interior surface  116  of the closed lower end  112  of mixing drum  100 .  
         [0044]    Drive shaft  150  is provided with a selectively detachable lovejoy coupling adjacent to motor  200 . This coupling allows the motor and motor mount to be easily detached from and reattached to the mixing assembly found at the lower end of drive shaft  150 . Ease of detachment is beneficial since separation of portable mixing device  10  into smaller segments allows the device to be more easily transported in and out of buildings, and up and down stairs, by a single individual. It also allows the device to be easily cleaned.  
         [0045]    Wiping assembly  400  is rigidly suspended from the underside of motor mount  220  by welding it to rod  226 , which is in turn bolted to the underside of plate  224  (FIG. 2). Wiping assembly  400  is formed of four thin, narrow, elongate rigid strips or tines  405 ,  410 ,  415 ,  420 . Each tine is identical and for purpose of illustration, outer right side tine  405  will be described in detail. Tine  405  is an elongate rectangle and is thus provided with a length, a width and a thickness. The length of tine  405  is such that it extends substantially throughout the length of mixing drum  100 . Preferably, the length of tine  405  is such that tine  405  extends approximately three-fourths of the length of mixing drum  100 . Tine  405  is further provided with a longitudinal axis which lies parallel to the length, and a longitudinal plane which corresponds to the plane which contains both the length and the width. The longitudinal axis of tine  405  lies in parallel to the longitudinal axis of internal frame  27 .  
         [0046]    Tine  405  has a first, or upper, end  422  which corresponds to the peripheral edge along the width. First end  422  is fixed to motor mount  220 . Tine  405  has a second, or lower, end  426  which corresponds to the peripheral edge along the width and which is opposed to and separated from the first end by the length. Tine  405  has a first edge  428  which corresponds to the peripheral edge along the length and lies perpendicular to the plate  224  of motor mount  220 , and a second edge  430  which corresponds to the peripheral edge along the length and which is opposed to and separated from first edge  428  by the width.  
         [0047]    Tine  405  is further provided with wiper  450 . Wiper  450  is an elongate rectangular sheet of resilient and flexible material, preferably rubber, and of approximately the same shape and dimensions as tine  405 . Wiper  450  lies abutting tine  405  such that wiper  450  only partially overlies tine  450 , resulting in the peripheral edge of wiper  450  extending beyond first edge  428  and from second end  426  of tine  405 .  
         [0048]    Wiper  450  is fixed to tine  405  using reinforcing plate  480 . Reinforcing plate  480  overlies wiper  450  such that wiper  450  is sandwiched between reinforcing plate  480  and tine  405 . This layered relationship is maintained by a plurality of through bolts  482 , which extend through each of said reinforcing plate  480 , wiper  450 , and tine  405 . Through bolts  482  are used at intervals along the length of tine  405 , and in the preferred embodiment, three through bolts  482  are employed.  
         [0049]    Each of the four tines  405 ,  410 ,  415 , and  420  extend rigidly downward from the underside of rod  226  adjacent to side edge  236  so as to intercept line formed by the diameter of internal frame  27  (and mixing drum  100 ) (FIG. 5). Two tines  405 ,  410  which correspond to the left outer tine  405  and the left inner tine  410  extend downward such that their respective longitudinal planes are parallel. The longitudinal planes of these tines  405 ,  410  lie at an angle of approximately +45 degrees relative to the lateral plane, where the lateral plane is defined as a vertical plane which extends laterally from right to left across the diameter of internal frame  27 . The remaining tines  415 ,  420 , which correspond to the right outer tine  420  and the right inner tine  415 , extend downward such that their longitudinal planes lie at an angle of approximately 45 degrees relative to the lateral plane, or at approximate 90 degrees to the respective longitudinal planes of left side tines  405  and  410 .  
         [0050]    Mixing assembly  500  is fixed to drive shaft  150  at the lower end of mixing drum  100 . Mixing assembly  500  consists of a fin mount plate  510 , an inner fin  560 , a set of intermediate fins  540 , and a set of outer fins  520 . Fin mount plate  510  lies perpendicular to and extends radially outward from drive shaft  150  forming a horizontal surface from which the mixing fins  560 ,  540 , and  520  extend. Fin mount plate  510  is generally in the shape of an equilateral triangle where the triangle sides are slightly cut away to provide an inward bow to the sides, and where the triangle apexes have been truncated. This shaping of fin mount plate  510  allows improved material flow within mixing drum  100  during agitation.  
         [0051]    Inner fin  560  is a rigid, elongate plate which extends upward from the upper side of fin mount plate  510 . Inner fin  560  is an elongate rectangle and is thus provided with a length, a width and a thickness. Inner fin  560  is further provided with a longitudinal axis which lies parallel to its length, and a longitudinal plane which corresponds to the plane which contains both its length and width. The longitudinal axis of inner fin  560  is parallel to the longitudinal axis of mixing drum  100 . The longitudinal plane of inner fin  560  lies perpendicular to a radius of cylindrical mixing drum  100 . Inner fin  560  is mounted to the upper side of fin mount plate  510  closely adjacent to said drive shaft  150  such that it lies a first radial distance from drive shaft  150 . Preferably, this distance is approximately 0.75 inches.  
         [0052]    Intermediate fin set  540 ′ is made up of three rigid, elongate plates which extend upward from the upper side of fin mount plate  510 . Each intermediate fin  540  of intermediate fin set  540 ′ is equidistant from the remaining intermediate fins  540  and from the longitudinal axis of mixing drum  100 . Each intermediate fin  540  is spaced from drive shaft  150  a second radial distance which is greater than the first radial distance. Preferably, this distance is approximately 3.75 inches, and positions each respective intermediate fin  540  midway between drive shaft  150  and a respective truncated apex. Most preferably, each intermediate fin  540  is positioned midway between drive shaft  150  and the interior surface  116  of mixing drum  100  along a radial line that extend from drive shaft  150  to a truncated apex.  
         [0053]    Each intermediate fin  540  is an elongate rectangle and is thus provided with a length, a width and a thickness. Each intermediate fin  540  is further provided with a longitudinal axis which lies parallel to its length, and a longitudinal plane which corresponds to the plane which contains both its length and width. The longitudinal axis of each intermediate fin  540  is parallel to the longitudinal axis of mixing drum  100 . The longitudinal plane of each intermediate fin  540  lies perpendicular to a radius of cylindrical mixing drum  100 .  
         [0054]    Outer fin set  520 ′ is made up of three rigid, elongate plates which extend both upward and downward from the peripheral edge of fin mount plate  510 . Each outer fin  520  of outer fin set  520 ′ is provided with a length, a width and a thickness, the thickness being very small relative to the length and width, and the width being small relative to the length. Each outer fin  520  is provided with a longitudinal axis which lies parallel to its length, and a longitudinal plane which corresponds to the plane which contains both its length and width.  
         [0055]    Each outer fin  520  has a first end  521  which corresponds to the peripheral edge along the width at the upper end of outer fin  520 , and a second end  522  which corresponds to the peripheral edge along the width at the lower end of outer fin  520  and which is opposed to and separated from first end  521  by its length.  
         [0056]    Each outer fin  520  has a first edge  526  which corresponds to the peripheral edge along the length and lies adjacent to and confronting interior surface  116  of mixing drum  100 . Second edge  528  of each outer fin  520  corresponds to the peripheral edge along the length and is opposed to and separated from first edge  526  by the width of outer fin. Each outer fin  520  is oriented such that second edge  528  lies so as to face drive shaft  150 .  
         [0057]    The respective second ends  522  of each outer fin  520  is provided with a widened portion  530  which extends radially inward toward drive shaft  150  from second edge  528  such that the appearance of the width of each outer fin  520  is that of the letter “L”.  
         [0058]    Each outer fin  520  has a mid portion  524  which extends between first end  521  and second end  522 . An outer fin  520  is mounted to the periphery of fin mount plate  510  at each truncated apex. Each outer fin  520  is suspended from its respective second edge  528  at a location in mid portion  524  so that first end  521  lies above fin mount plate  510  and second end  522  lies below fin mount plate  510 .  
         [0059]    The longitudinal axis of each outer fin  520  is not parallel to the longitudinal axis of mixing drum  100 , rather, the longitudinal axis of each outer fin lies at angle relative to the vertical such that when viewed facing first edge  526 , first (upper) end  521  lies to the left of second (lower) end  522 . In operation, as drive shaft  150  rotates each outer fin  520  travels about the circumference of the drum such that the widened second (lower) end  522  leads and the first (upper) end  521  trails. The resulting effect of this angled fin is that the mix which has settled in the lower regions of mixing drum  100  is dislodged and urged upward, greatly improving the quality of the agitation with mixing drum  100 .  
         [0060]    Each outer fin  520  is equidistant from the remaining outer fins  520  and from the longitudinal axis of mixing drum  100 . Each outer fin  520  is spaced from drive shaft  150  a third radial distance which is greater than the first and second radial distances. Preferably, this distance is approximately  9 . 5  inches, and positions each respective outer fin  520  such that it extends outwardly from the peripheral edge of a respective truncated apex. Most preferably, outer fin  520  is positioned as follows: Second edge  526  is closely adjacent to and confronts the interior surface  116  of the side wall of mixing drum  100 . Second end  522 , located below fin mount plate  510 , is closely adjacent to and confronts the interior surface  116  of the closed lower end  112  of mixing drum  100 . Widened portion  530  is radially aligned to provide a sweeping action across lower end  112 . Mid portion  524  is provided in a length which locates first end  521  above fin mount plate  510  adjacent to but spaced apart from the open upper end  110  of mixing drum  100 .  
         [0061]    Mixing assembly  500 , which consists of inner fin  560 , intermediate fin set  540 ′, and outer fin set  520 ′ extend from fin mount plate  510 , which is in turn fixed to drive shaft  150 . Thus each individual fin travels one complete revolution about the interior of mixing drum  100  for each revolution of drive shaft  150 . Each first end  521  of each outer fin  520 , each intermediate fin  540 , and interior fin  560  extend upward from fin mount plate  510  and are provided with respective lengths so as to cooperatively co-mingle with tines  405 ,  410 ,  415 , and  420 . Additionally, each first end  521  of each outer fin  520  and each intermediate fin  540  intermittently contact the wipers  450  of tines  405 ,  410 ,  415 , and  420  to provide an extremely efficient agitation source. Referring now to FIGS. 5 and 7, the respective first ends  521  of each outer fin  520  contact wiper  450  of right outer tine  420  in sequence during each rotation. Each intermediate fin  540  is sequentially in momentary contact with wiper  450  of right inner tine  415  and left outer tine  405  during each rotation so that both surfaces of each intermediate fin  540  is cleaned. Inner fin  560  passes between drive shaft  150  and respective left and right inner tines  410 ,  415 , making contact with the wiper  450  of tine  410 . Wipers  450  sweep across the surface of each fin  560 ,  540 ,  520 , to remove any accumulated of unmixed material therefrom and to prevent any buildup of materials on fin surfaces thus greatly increasing the efficiency of agitation within mixing drum  100 .  
         [0062]    Lower agitating bars  136  are a pair of stationary, elongate rods which are located adjacent the closed lower end  112  of mixing drum  100 . Lower agitating bars  136  are horizontally oriented and extend radially outward. Placed on opposing sides of drive shaft  150 , lower agitating bars  136  extend between the underside of fin mount plate  510  and above the respective widened portions  530  of outer fin set  520 ′. This configuration allows lower agitating bars  136  to cooperatively co-mingle with widened portions  530  of outer fin set  520 ′ preventing accumulation of unmixed material below fin mount plate  510  and increasing agitation in this region of the interior of mixing drum  100 .  
         [0063]    Lower agitation bars  136  are supported by posts  140  which extend vertically upward from lower agitation assembly plate  130 . Posts  140  lie adjacent to and on opposing sides of cylindrical bushing  132 , which receives both drive shaft  150  and packing material  134 .  
         [0064]    In operation, motor  200  causes drive shaft  150  to rotate at  60  revolutions per second, thus each fin  520 ,  540 ,  560  of the mixing assembly  500  travels a complete revolution once every second. Because the wiping assembly  400  is configure to extend completely across the diameter of mixing drum  100 , each fin  520 ,  540 ,  560  of the mixing assembly  500  passes through the tines  405 ,  410 ,  415 ,  420  of wiping assembly  400  two times per second. This motor speed is completely adequate for provide very successful mixing.