Abstract:
A guide for the blade of a band saw providing support for the rear edge and sides of the blade. The guide utilizes two cylindrical rings or anvils that may be adjusted to contact the sides of the blade. A rotating spool within the anvils provides the support for the rear edge of the blade. The spool may be easily adjusted to provide support for blades of varying depth. The entire guide may be mounted on the guide arm of most band saw blades and pivoted into position through the use of an adjustable saddle.

Description:
FIELD OF THE INVENTION  
         [0001]    This invention relates to band saws. More specifically, the invention involves a guide for the blade of a band saw for stabilizing and aligning the blade while an object is being cut by the blade.  
         BACKGROUND OF THE INVENTION  
         [0002]    Anyone having performed any work on a band saw readily understands the difficulties involved due to the nature of the saw. The blade of the band saw is generally flexible. This flexibility allows the blade to ride in a repetitively circular manner around wheels driven by a motor through a cutting zone on the saw. However, the flexible nature of the blade also lends itself to undesirable movement. While pushing an object for cutting through the cutting zone, the blade may shift horizontally or twist as a result of the force against the blade exerted by the object being cut. This shifting or twisting may result in a loss of precision for purposes of the intended cut as the angle of the blade changes. Additionally, the force exerted on the blade may also negatively affect the alignment of the blade on the wheels of the saw.  
           [0003]    Prior art devices have attempted to stabilize blade movement with some success. For example, in the patent to Duginske et al. (U.S. Pat. No. 4,920,846), fiber guide blocks mounted on the sides of the blades have been used to restrict side-to-side movement. However, these devices are of limited usefulness because of the great friction caused when the blade contacts the blocks.  
           [0004]    One improvement to these blocks is taught in the patent to Foley (U.S. Pat. No. 3,145,604). In Foley, a guide is provided with a set of angled wheels that rotate as the blade passes between the wheels. While the guide provides protection from horizontal movement, due to the angled nature of the wheels it is generally complex to adjust to maintain proper alignment of the blade in the cutting zone. Moreover, this angling reduces support by reducing contact area. Additionally, the wheels provide no mechanism for adjustment for blades of different sizes. Thus, the potential surface area of the support of the wheels against the blade remains constant. As larger blades are used, less support is provided.  
           [0005]    In another implementation of wheels, the patent to Karubian (U.S. Pat. No. 4,141,142) teaches the use of a guide with two side wheels each rotating in the same direction as the blade with their axes of rotation being parallel to the depth (front edge to the back edge) of the blade and perpendicular to the length of the blade in the cutting zone. An additional back wheel with an axis of rotation perpendicular to the depth and length of the blade also supports the blade. The devices generally eliminate the friction on the blade. Thus, as some friction is desirable to scour or clean the blade, this device has limited usefulness. Moreover, due to the curvature of the wheel approaching the blade, debris from a cutting operation on the saw may serve to chock or jam rotation of the wheels. This will result in unsatisfactory performance of the band saw.  
         BRIEF DESCRIPTION OF THE INVENTION  
         [0006]    An objective of the present invention is to provide an easy to use adjustable guide for band saws.  
           [0007]    Another objective of the present invention is to provide a guide that provides thorough support against twisting and horizontal movement.  
           [0008]    A further objective of the present invention is to provide such support while reducing friction to minimize blade and guide wear.  
           [0009]    A still further objective of the present invention is to provide a guide to prevent jamming caused by debris from the band saw.  
           [0010]    Additional objectives will be apparent from the description of the invention as contained herein.  
           [0011]    In its broadest aspect, the present invention involves a band saw guide with two opposing rotating cylindrical rings or anvils. The anvils rotate parallel with the sides of the saw blades to provide for maximal surface contact. Thus, the anvils provide lateral support for the blade of a band saw to prevent the blade from lateral movement and undesired twisting. The anvils also scour and clear debris from the blade. These rings or anvils are mounted to bearings and installed within an adjustable guide head.  
           [0012]    In addition, the band saw guide combines rearward support for the blade using a rotating spool supported within the cylindrical anvils. In a preferred embodiment, the rotating spool has multiple steps. With the steps and a means for adjusting the spool, the guide may be easily used with blades of different depths.  
           [0013]    The guide is also designed for easy installation on many different band saws. Through the use of a pivoting saddle and a yoke, the guide may be mounted to an existing guide arm of most band saws. The guide head then may be pivoted into position behind the blade through an adjustment on the saddle. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    [0014]FIG. 1 depicts one type of band saw using a guide of the present invention;  
         [0015]    [0015]FIG. 2 depicts an exploded view of an embodiment of the band saw guide of the present invention showing the components thereof;  
         [0016]    [0016]FIG. 3 is a top-down view of an embodiment of the band saw guide with a cross-section of the guide head taken along line  3 - 3  of FIG. 1, but illustrating the use of a large blade;  
         [0017]    [0017]FIG. 4 is a side view of an embodiment of the band saw guide of FIG. 3 with a cross-section of the yoke and guide head taken along line  4 - 4  of FIG. 3;  
         [0018]    [0018]FIG. 5 is a top-down view of an embodiment of the band saw guide with a cross-section of the guide head taken along line  3 - 3  of FIG. 1, but illustrating the use of a small blade;  
         [0019]    [0019]FIG. 6 is a side view of an embodiment of the band saw guide of FIG. 5 with a cross-section of the yoke and guide head taken along line  5 - 5  of FIG. 5.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0020]    A band saw guide G of the present invention installed on a band saw S is illustrated in FIG. 1. The guide G mounts to a band saw S in the region of the cutting zone Z. The guide G is made from three parts including a guide head  10 , a yoke  12  and a saddle  14 . Generally, the guide head  10  serves as a housing for the adjustment and stabilization components used for guiding the blade B. The yoke  12  serves the purpose of securing the guide head  10 . The saddle  14  is used to attach the yoke  12  to a guide arm or bar  16  mounted on the band saw S behind the path of the blade B.  
         [0021]    [0021]FIG. 2 illustrates the components of the guide head  10 . The guide head  10  has a proximal threaded head member  20 A and distal threaded head member  20 B. Each head member  20 A and  20 B contains a rotating bearing  22 A,  22 B. A cylindrical ring or anvil  24 A,  24 B is press fitted to each rotating bearing  22 . The outer circular surfaces of the edge of the anvils  24 A,  24 B are parallel to the surfaces of the sides of the blade B to maximize contact with the blade B and thus minimize twisting or lateral movement. Since the anvils will be in contact with the sides of the blade B during operation, the anvils  24 A,  24 B are preferably made from hardened steel. Optionally, the outer edges of the anvils may be extended or enlarged to increase the surface area that comes in contact with the blade B during operation.  
         [0022]    Residing within the head members  20 A and  20 B is a blade spool  26 , which will be in contact with the rear edge of the blade B in operation. In one embodiment of the invention, the blade spool  26  is simply made from a cylinder post  28  and circular disk  30  only (not shown). The circumference of the disk  30  is sized to fit within the cavity of the distal anvil  24 B. An aperture within the proximal head member  20 A is sized to receive the cylinder post  28 . A washer  29  in the aperture provides the bearing support for the cylinder post  28  while allowing the cylinder post  28  to rotate. In this embodiment of the spool  26 , no adjustment for blades of different depths is provided.  
         [0023]    In an alternative embodiment of the invention, the spool  26 , in addition to the cylinder post  28  and circular disk  30 , has one or more circular steps  32 , each with a different radius. Thus, each step  32  provides a different level for the rear edge of blades of different depths. In this embodiment, a spring  34  extends from within the cylinder post  28  to the proximal head member  20 A, which may contact it by a ball bearing. The disk  30  may slide laterally or axially within the distal anvil  24 B. An adjustment aperture  36  in the distal anvil  24 B receives a spool adjustment member  38  to contact the disk  30  at a ball bearing.  
         [0024]    The preferred spool adjustment member  38  is associatively gauged with the spool  26  to allow metered adjustment from one step  32  to another. To this end, the thread width of a threaded spool adjustment member  38  may be coordinated with the width of the steps  32 , each having a common width, so that a single turn of the threaded spool adjustment member  38  will allow the spool  26  to move from one step to the next. In this embodiment, the threaded spool adjustment member  38  has a slot along its shaft. A pin  46  with a curved tip contained by a threaded stop  40  and pin spring  42  engages the shaft and slot of the adjustment member. As the adjustment member  38  is turned, the slot and pin allow for visual and tactile feedback with each turn while changing from one step to the next.  
         [0025]    Continuing with FIG. 2, the yoke  12  has of a guide head aperture  44 . The aperture  44  is threaded to receive the head members  20 A,  20 B. A blade slot  46  through a portion of the aperture  44  is provided to allow the blade to pass through the yoke  12 . A gap  48  in the yoke  12  allows the yoke  12  to be tightened down around the head members  20 A,  20 B using a threaded adjustor  50  (shown in FIGS.  3 - 6 ) in the top portion of the yoke  12  to restrict turning or adjustment of the head members  20 A,  20 B.  
         [0026]    The saddle  14  is connected with the yoke  12  on a pivot pin  52  through pivot holes  54  and  56 . The angle of the yoke  12  around the pivot pin  52  is adjusted with pivot adjustment  62  through slot  60 . Thus, the yoke  12  with guide head  10  may be pivoted toward the blade or away from the blade as desired. As an alternative embodiment, the saddle  14  may act as a sleeve to receive the yoke  12  without a pivot pin  52 . In this embodiment (not shown), the yoke  12  may slide laterally in the saddle  14  to allow the guide head  10  to be moved away from or near to the blade B for saw or other blade adjustment purposes. An adjustment mechanism, such as a threaded fastener, is used to restrict or allow the lateral movement of the yoke  12  in the saddle  14  when desired.  
         [0027]    The benefits of this apparatus, if not immediately apparent from the foregoing description of components, will be clearer by examining FIGS. 3 through 6 in conjunction with a description of the guide in use. More specifically, FIGS. 3 and 4 show the installation of a large blade and FIGS. 5 and 6 show the installation of a small blade. With the saddle  14  mounted to the guide bar  16 , the proximate and distal anvils  24 A,  24 B are adjusted to create a space or gap for a blade between them by rotating the head members  20 A,  20 B counter-clockwise. The blade spool  26  may be adjusted to select an appropriate step  32  on the spool such that the maximum area of the blade B, excluding the blade teeth, may be within the guide head between the anvils  24 A,  24 B. Thus, for the large blade of FIGS. 3 and 4, the spool adjustment member  38  is rotated counter-clockwise to allow the spool  26  to slide laterally so that a portion of the cylinder post  28  is aligned with the distal anvil  24 B. For a small blade, the spool adjustment member  38  is rotated clockwise to allow the spool  26  to slide laterally or axially so that the step  32  with the largest radius is aligned with the distal anvil  24 B. Alternatively, other steps  32  may be selected.  
         [0028]    The combined guide head  10  and yoke  12  may, after the adjustments as describe above, then be pivoted into position behind the blade by adjusting the pivot adjustment  62  such that the rear edge of the blade B will rest against the spool  26  through blade slot  46  of the yoke  12 . Then, head members  20 A and  20 B may be rotated clockwise such that the proximal and distal anvils  24 A,  24 B tighten or clamp against the sides of the blade B. In addition, since both head members  20 A,  20 B may be rotateably adjusted towards the sides of the blade B, the head members  20 A,  20 B can be aligned laterally to keep the blade B perfectly vertical within the guide G relative to the cutting zone Z and the peripheral edge of the wheels WA, WB of the band saw S. Once head members  20 A,  20 B are tightened, the top portion of the yoke  12  may be tightened down to prevent movement of the head members during band saw operations using a threaded fastener  50  in the yoke. This tightening effectively reduces the circumference of the guide head aperture  44 , thereby restricting movement of the head members.  
         [0029]    In operation, due to the presence of the bearings  22 A,  22 B, the anvils  24 A,  24 B will rotate within the head members  20 A,  20 B as the blade B trains through the cutting zone Z following the path of the wheels WA, WB. Similarly, the spool  26  will rotate. The axis of rotation of the anvils  24 A,  24 B and the spool  26  will be perpendicular to the length of the blade and perpendicular to the depth of the blade. This rotation is caused by the contact of the blade B against the anvils  24 A,  24 B and the spool  26 . Thus, the blade B will be subjected to rotational friction by the anvils  24 A,  24 B as they move across the blade depth and down or up the blade length.  
         [0030]    This rotational action has several benefits. Since the spool  26  and the anvils  24 A,  24 B rotate, friction against the blade is minimized when compared with stationary block type guides. Although some wear will occur, since the entire edge of each anvil will rotate to contact the blade surface, the anvils  24 A,  24 B will wear evenly reducing the need for anvil maintenance. In addition, the friction that is created results in the scouring of the sides of the blade while slewing saw debris away from the guide to avoid jamming.  
         [0031]    In the preferred embodiment, all of the adjustments required by the guide G may be performed by hand, without tools.  
         [0032]    Although the invention has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of an application of the principles of the invention. Numerous modifications, in addition to the illustrative embodiments of the invention discussed herein may be made and other arrangements may be devised without departing from the spirit and scope of the invention.