Abstract:
An adjustable blade guide for a band saw such as a band saw on a sawmill utilized for sawing lumber. The blade guide is easily adjusted to account for variations in the diameter of the lumber to be cut, and is self locking.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to an adjustable blade guide for a band saw such as a band saw on a sawmill utilized for sawing lumber. The blade guide is easily adjusted to account for variations in the diameter of the lumber to be cut, and is self locking. 
       BACKGROUND OF THE INVENTION 
       [0002]    A conventional band saw is often used in sawmills. Such a band saw typically has a relatively large, circular, band saw blade, mounted along the path of travel of a log placed on a suitable moving bed with a drive mechanism for advancing the log against the blade. Alternatively, the log remains stationary and the band saw is mounted on a carriage which is capable of transverse displacement along the log. 
         [0003]    One problem faced with band saws having large band saw blades is the tensioning of said blade. The blade moves in a generally circular path, typically around two band wheels, one of which is powered by a motor, either via direct drive or a belt drive. The portion of the saw blade between the two band wheels is often exposed and largely unrestrained; complex forces on the blade as it passes through the log result in substantial and undesired transverse motion of the blade, resulting in reduction in efficiency, reduction in accuracy of the cut, and an increase in wear on the saw blade and sometimes its drive assembly and motor. 
         [0004]    In order to counteract such forces, various mechanisms are used. For example, a blade tensioning system may be used to provide increased tension on the blade. 
         [0005]    This will help restrict transverse motion, but often at the cost of added parts, and an increase in tension (and a resulting increase in wear) on the band wheels. Another example of a mechanism used to decrease transverse motion on the blade is the use of one or more blade guides which act to guide the blade. Typically, a blade guide will be rigidly affixed to the band saw, and extend into, or immediately proximal to, the path of the blade. A blade guide will often have an upper and a lower jaw and rear thrust plate, each having roller wheels or other low friction running surface, or alternatively, one-sided support surface and rear thrust plate. The flat portion of the blade, or in the alternative, the straight edge of the blade, will travel along the roller wheels. Since the blade guide is affixed to the band saw, it helps prevent transverse motion while minimally affecting the desired rotatory blade motion. 
         [0006]    There are several prior inventions for band saws. 
         [0007]    U.S. Pat. No. 4,275,632 describes a portable sawmill comprising a U-shaped support or carriage, holding a band saw. When in use, a log is placed between the two guide rails and is supported in place by a jacking mechanism with adjustable shelves. The band saw is in a generally horizontal position (though with one end slightly elevated), and does not adjust in a vertical direction; instead, the log itself is moved up and down using a jacking mechanism. The patent describes a blade tensioning system as well as guide rollers. The guide rollers engage the straight edge of the band saw as an aid in holding the band saw in position on the wheel. 
         [0008]    Canadian Patent No. 1,200,180 describes a portable sawmill having a band saw on a carriage. The carriage is moveable along the guide rail along two sets of wheels, one engaged with the upper side of the guide rail and the other with the lower side. The band saw comprises a circular band saw blade which travels along two band saw wheels. The band saw has a stationary blade guide, having a set of blade guide wheels, guides the blade on the lower drive side. The band saw also has a movable blade guide, having a set of blade guide wheels, on the driven side. The movable blade guide allows for adjustment of the length of the exposed cutting section of the blade. The adjustable blade guide is attached to a telescopic guarded tube arrangement which protects a portion of the blade. The adjustable blade guide is adjusted through a screw and nut “T” handle, which allows tightening of the assembly. To adjust the adjustable blade guide, one unscrews the screw on the T handle, then moves the blade guide to the desired position. Then one tightens the screw on the T handle, affixing the blade guide in position. 
         [0009]    The LumberMate™ band sawmill (http://www.norwoodindustries.com) is a portable sawmill having a band saw with a circular band saw blade which rotates around two band saw wheels. The band saw has a stationary blade guide, having a set of blade guide wheels, guides the blade on the lower drive side. The band saw also has a movable blade guide, having a set of blade guide wheels, on the driven side. The movable blade guide allows for adjustment of the length of the exposed cutting section of the blade. Similarly to the blade guide described in CA 1,200,180, the adjustable blade guide is adjusted through a screw and nut “T” handle, which allows tightening of the assembly. To adjust the adjustable blade guide, one unscrews the screw on the T handle, then moves the blade guide to the desired position. Then one tightens the screw on the T handle, affixing the blade guide in position. 
         [0010]    There is a need for an improved portable sawmill having an adjustable blade guide that is easy to adjust and self locking. 
       SUMMARY OF THE INVENTION 
       [0011]    The present invention provides a saw head for a sawmill, said saw head comprising: a frame, a drive driving a saw blade, and a blade guide contacting said saw blade and capable of decreasing transverse and/or vertical movement of the band saw blade when said blade is in motion. The blade guide is affixed to a guide support which is slidably engaged to the frame. The guide support has a guide support adjuster pivotally connected thereto at a proximal end, having a distal end, and having teeth on its lower edge, said teeth capable of engaging a peg affixed to the frame. When the distal end is lifted, the guide support is capable of horizontal motion thereby adjusting the position of the blade guide on the saw blade, and, when the distal end is dropped, at least one of said teeth engage the peg, locking the guide support in place and preventing said horizontal motion. 
         [0012]    The invention also teaches a second blade guide affixed to the frame, contacting said saw blade, and capable of decreasing transverse movement of the saw blade when said blade is in motion, whereby the line between the blade guide and the second blade guide define a cutting section. 
         [0013]    In an embodiment the sawmill comprises a sawmill base, a sawmill carriage sitting on top of said sawmill base, said sawmill carriage having at least one saw head support capable of supporting the saw head. The sawmill base extends in a generally horizontal direction and comprises at least one rail, and the carriage is capable of longitudinal displacement across said rail. 
         [0014]    In an embodiment, the saw head, when affixed to the saw head support, is capable of vertical displacement thereto. 
         [0015]    The saw blade can be a band saw blade or a reciprocating saw blade. 
         [0016]    The invention also provides a sawmill, comprising a sawmill base, extending in a generally horizontal direction, and having at least one rail and a sawmill carriage, capable of longitudinal displacement across said rail. The sawmill carriage has at least one vertical support, extending in a generally vertical direction from said base, and supporting a saw head of the invention capable of vertical displacement along the vertical support. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]      FIG. 1  is a front elevation view of a band saw head according to one aspect of the present invention, with the protective cover off so that the internal components can be viewed, and is labeled with its major components. 
           [0018]      FIG. 2  is a rear elevation view of the band saw head of  FIG. 1 . 
           [0019]      FIG. 3  is a front right side perspective view of the band saw head of  FIG. 1 . 
           [0020]      FIG. 4  is a front perspective view of the band saw head of  FIG. 1  with additional components removed for a better view of certain pertinent internal components. 
           [0021]      FIG. 5  is a rear bottom perspective view of the band saw head of  FIG. 1 . 
           [0022]      FIG. 6  is a front left perspective view of the adjustable blade guide mechanism from the band saw head of  FIG. 1 , shown in isolation. 
           [0023]      FIG. 7  is a rear right perspective view of the adjustable blade guide mechanism of  FIG. 6 . 
           [0024]      FIG. 8  is a close-up front left perspective view of the front side of the adjustable blade guide mechanism on a band saw head according to a further aspect of the present invention. 
           [0025]      FIG. 9  is a front side perspective view of the band saw head of  FIG. 1  as seen installed on a sawmill. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0026]    The present invention provides a simple and effective, adjustable blade guide mechanism for a band saw. The adjustable blade guide is self locking in that it can be adjusted to a desired position without the need for screwing or unscrewing restraining bolts. The blade guide&#39;s design enables it to be quickly adjusted with one hand by an operator. The self locking feature reduces the number of steps required by the operator in adjusting the blade guide, thus increasing efficiency and safety of operation. 
         [0027]    An embodiment of the present invention will now be described as shown in  FIGS. 1-5  and  9 . 
         [0028]    Band saw head  20  is designed to be used as part of a sawmill (as shown in  FIG. 9  only). Briefly, band saw head  20  is fitted to carriage  18  which is capable of longitudinal displacement on rails  15  of sawmill base  16 . Band saw head  20  is capable of vertical displacement in relation to sawmill base  16  through displacement along depth of cut ruler  52 . Tension on the blade is controlled by saw head tension T handle  50 . The saw head can be moved vertically along vertical posts  66  by operation of crank  68  ( FIG. 9 ). 
         [0029]    The band saw head  20  has a saw head plate stack  29  which acts as support for drive band wheel  22  and free band wheel  24  ( FIG. 2 ). Band saw blade  42  is entrained on and travels along outer wheel  23  of drive band wheel  22  and free wheel  24 , and travels along cutting section  60 , located between the drive band wheel  22  and free band wheel  24 . Band saw blade  42  has transversely extending teeth capable, when in motion, of cutting a log. An inner wheel  25  of drive band wheel  22  is connected to a motor  49  by way of belt  46  which runs along inner wheel  25  and drive pulley  48  ( FIG. 3 ). Tension on belt  46  is controlled by way of tensioning pulley  47 . In use, motor  49  turns drive pulley  48 , which, in turn, turns drive band wheel  22  and, as a result, saw blade  42 , which rotates around drive band wheel  22  and free band wheel  24 . 
         [0030]    Tensioning pulley  47  can also be used as a clutch for the saw blade  42 ; instead of continuously shutting off and turning on the motor  49  to activate the cutting action of saw blade  42 , tension can be released from belt  46  by adjusting tensioning pulley  47 . Releasing tension in belt  46  results in the free spinning of drive pulley  48  and a decrease of rotatory force on saw blade  42 , resulting in the stopping of the saw blade  42 . Starting and stopping saw blade  42  in this manner decreases wear on motor  49  and belt  46 , improving the longevity of these parts. 
         [0031]    Within the path of saw blade  42  is cutting section  60 , which is the section in which saw blade  42  is generally free of obstruction and can be used to cut a log. On one side of the cutting section  60  is an adjustable blade guide  28  (also seen in  FIGS. 6 to 8 ). Adjustable blade guide  28  has a lower jaw  62  and an upper jaw  64 , each having a blade guide roller, bearings, or low friction ceramic thrust blocks (not shown). In a preferred embodiment, three low friction ceramic thrust blocks are provided, one in each horizontal jaw plus one vertical at the back. Alternatively bearings are used at all three contact points or other low friction interfaces (wood for example). Note that a blade guide can also have only a top jaw plus rear thrust support (2-point support instead of three). On the other (driven) side of the cutting section  60  is a stationary blade guide  26  also having a lower jaw (not shown) and an upper jaw (not shown), each having a blade guide ceramic thrust blocks or other low friction contacts as discussed above. In operation, the saw blade travels between the blade guide rollers of both the adjustable blade guide  28  and the stationary blade guide  26 . In use, the blade guide rollers prevent undesired transverse and/or vertical movement of the saw blade. 
         [0032]    Stationary blade guide  26  is typically, and as shown, affixed to sawhead plate stack  29  via a vertical blade guide post  70  extending downwards ( FIG. 2 ). Adjustable blade guide  28  is affixed to guide support  32 , which is slidably engaged to guide slide  34 , which, itself, is mounted on sawhead plate stack  29 . Thus, the adjustable blade guide  28  is capable of horizontal displacement with respect to sawhead plate stack  29  through the displacement of guide support  32 , along guide slide  34 , thus allowing for variation of the length of cutting section  60 . Also mounted on guide support  32  is guard  30  which extends horizontally away from cutting section  60  and protects blade  42 . Guard  30  is adjustable and removable through the loosening of guard screw  31 . 
         [0033]    Pivotally attached to guide support  32  at its proximal end through pivot screw  40  is guide support adjuster  36  having guide support handle  44  at its distal end. Guide support adjuster  36  has teeth  38  on its lower edge, which can engage peg  58  (see  FIG. 4 ) which is attached to saw head plate stack  29 . When teeth  38  engage peg  58 , guide support adjuster  36  locks and prevents horizontal displacement of guide support  32  along guide slide  34 , thus locking the horizontal location of adjustable blade guide  28 . Thus, to adjust adjustable blade guide  28  in a horizontal direction (and thus adjust the length of cutting section  60 ), an operator needs only to lift guide support handle  44  in an upwards direction, thereby pivoting guide support adjuster  36  around pivot screw  40  and disengaging teeth  38  from peg  58 . The operator then simply pushes or pulls on guide support handle  44  thus displacing it and adjustable blade guide  28 , through the displacement of guide support  32  along guide slide  34 . Once the desired horizontal position is achieved, the operator need only release guide support handle  44 . The guide support adjuster  36  will then fall, engaging one of teeth  38  on peg  58  and thereby locking horizontal displacement of adjustable blade guide  28 . 
         [0034]      FIGS. 6 and 7  show the guide support  32  and accompanying parts in isolation. Adjustable blade guide  28  is affixed to guide support  32 , which is slidably engaged to guide slide  34 . Pivotably attached to guide support  32  at a proximal end by pivot screw  40  is guide support adjuster  36  having teeth  38  on its lower length. Distal end of guide support adjuster  36  has guide support handle  44  which can be used by an operator to vertically displace guide support adjuster  36  around pivot screw  40 . Guard  30  is affixed to guide support  32  by guard screw  31 . Adjustable blade guide  28  has lower jaw  62  and upper jaw  64  which contain ceramic thrust blocks or the like (not shown) and have a rear thrust block (not shown). Lower jaw  62  and upper jaw  64  envelop the saw blade  44  when in use. 
         [0035]      FIG. 8  is a close-up of the adjustable blade guide  28  in said sawmill. Notably,  FIG. 8  shows the adjustable blade guide  28  enveloping saw blade  42 . The lower jaw  62  and upper jaw  64  of adjustable blade guide  28  envelop the saw blade  42 , and are affixed to guide support  32 , which slidably engages guide slide  34 , which, in turn, is mounted onto the underside of sawhead plate stack  29 . Mounted to guide support  32  on pivot screw  40  is guide support adjuster  36 . Also affixed to guide support  32  by guard screw  31  is guard  30 , which is shown with alternating black and white stripes and a “danger” symbol. Guard screw  31  is a standard T-bolt screw. 
         [0036]    It is to be understood that the present invention is not limited to the embodiments described above, but encompasses any and all embodiments within the scope of the following claims. 
       ELEMENT LIST 
       [0000]    
       
           15 —rails 
           16 —sawmill base 
           18 —carriage 
           20 —band saw head 
           21 —guard 
           22 —drive band wheel 
           23 —outer wheel 
           24 —free band wheel 
           25 —inner wheel 
           26 —stationary blade guide 
           28 —adjustable blade guide 
           29 —saw head plate stack 
           30 —guard 
           31 —guard screw 
           32 —guide support 
           34 —guide slide 
           36 —guide support adjuster 
           38 —teeth 
           40 —pivot screw 
           42 —blade 
           44 —guide support handle 
           46 —belt 
           47 —tensioning pulley 
           48 —drive pulley 
           49 —motor 
           50 —blade tensioning T-handle 
           52 —depth of cut ruler 
           54 —guide adjuster 
           56 —guide adjuster 
           58 —peg 
           60 —cutting section 
           62 —lower blade guide jaw 
           64 —upper blade guide jaw 
           66 —vertical posts 
           68 —crank 
           70 —vertical blade guide post