Abstract:
A belt tensioning device is provided for an apparatus such as a lathe which includes a centering member adapted to be attached to a workpiece and is supported for rotation about an axis. A motor is spaced from the centering member and is supported by a pivot member. A drive pulley is attached to the motor and a driven pulley is attached to the centering member. A belt is engaged between the drive pulley and the driven pulley for transmitting driving torque from the motor to the centering member. A belt tensioning device is provided for moving the pivot member between a first position wherein the belt is tensioned between the drive and driven pulleys and a second position wherein the belt is loosened between the drive and driven pulleys.

Description:
FIELD 
       [0001]    The present disclosure relates to woodworking lathes and more particularly, to belt tensioning designs for a lathe. 
       BACKGROUND 
       [0002]    The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. 
         [0003]    A lathe is a woodworking tool which spins a block of wood or other material to perform various operations such as cutting, sanding, knurling or deformation with tools that are applied to a workpiece to create an object which has symmetry about an axis of rotation. The material is held in place by either one or two centers, at least one of which can be moved horizontally to accommodate varying material lengths. Various types of spindles, cue sticks, table legs and baseball bats are examples of objects that can be produced on a lathe. 
         [0004]    In current lathe designs, an electric motor or other source of rotary power includes a drive pulley which is connected to a drive belt which drives a driven pulley that is connected to the workpiece for turning the workpiece about a central axis. In a typical lathe, the user manually tensions the drive belt and clamps it in place so that the belt is provided with sufficient tension so as not to slip on the drive or driven pulleys. Although this prior belt tensioning technique is satisfactory for its intended purpose, improvements to the belt tensioning design can simplify the technique and/or prevent the necessity for repeated belt tensioning as the belt is stretched or worn through use. 
       SUMMARY 
       [0005]    A belt tensioning device is provided for a device such as a lathe including a centering member adapted to be attached to a workpiece and being supported for rotation about an axis. A motor is spaced from the centering member and supported by a pivot member. A drive pulley is attached to the motor and a driven pulley is attached to the centering member. A belt is engaged between the drive pulley and the driven pulley for transmitting driving torque from the motor to the centering member. A device is provided for moving the pivot member between a first position wherein the belt is tensioned between the drive and driven pulleys and a second position wherein the belt is loosened between the drive and driven pulleys. A locking device is operable to retain the pivot member in the loosened position. The belt tensioning device can be used with other power tools such as a drill press and other power tools that use a belt drive. 
         [0006]    Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
     
    
     
       DRAWINGS 
         [0007]    The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
           [0008]      FIG. 1  is a perspective view of a prior art lathe utilizing a known belt tensioning; 
           [0009]      FIG. 2  is a perspective view of a belt tensioning device according to the principles of the present disclosure; 
           [0010]      FIG. 3A  is an end view of the belt tensioning device shown in  FIG. 2 , with the belt in a tensioned condition; 
           [0011]      FIG. 3B  is a schematic view of the belt tensioning device shown in  FIG. 2 , with the belt loosened; 
           [0012]      FIG. 3C  is a perspective view of latching mechanism for holding the belt tensioning device in a loosened condition; 
           [0013]      FIG. 4  is a perspective view of an alternative belt tensioning device in accordance with the principles of the present disclosure; 
           [0014]      FIG. 5  is a side schematic view of the belt tensioning device shown in  FIG. 4 ; 
           [0015]      FIG. 6  is a front plan view of the belt tensioning device shown in  FIG. 4 ; 
           [0016]      FIG. 7A  is a perspective view of an alternative belt tensioning device according to the principles of the present disclosure; 
           [0017]      FIG. 7B  shows a perspective view of the pull knob device of  FIG. 7A  shown in an unlocked postion; 
           [0018]      FIG. 7C  shows a perspective view of the belt tensioning device of  FIG. 7  with the belt shown in a loosened condition; 
           [0019]      FIG. 7D  shows a perspective view of the pull knob device of  FIG. 7A  shown in a locked postion; 
           [0020]      FIG. 7E  is an exploded perspective view of the belt tensioning device shown in  FIG. 7A ; 
           [0021]      FIG. 8  is a schematic view of the belt tensioning device shown in  FIG. 7 ; 
           [0022]      FIG. 9  is a perspective view of still another belt tensioning device according to the principles of the present disclosure; 
           [0023]      FIG. 10  is a schematic view of the belt tensioning device shown in  FIG. 9 ; 
           [0024]      FIG. 11  is a schematic view of a belt tensioning device according to still another embodiment of the present disclosure; 
           [0025]      FIG. 12  is a side view of the belt tensioning device shown in  FIG. 11 . 
       
    
    
     DETAILED DESCRIPTION 
       [0026]    The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. 
         [0027]    With reference to  FIG. 1 , a lathe  10  is shown. The lathe  10  is a woodworking tool which spins a block of wood or other material to perform various operations such as cutting, sanding, knurling or deformation with tools that are applied to the workpiece to create an object which has symmetry about an axis of rotation. The lathe  10  includes a base structure  12  which supports a motor  14  which is drivingly connected to a first center member  16  as will be described herein. A workpiece is supported between the first center member  16  and a second center member  18  which can be moved horizontally relative to the support structure  12  in order to accommodate varying material lengths of the workpiece. As is known in the art, horizontal movement of the second centering member  18  can be accomplished by rotary dial  20  or by other adjustment mechanisms as are known in the art. As shown in  FIG. 1 , an on/off switch  22  can be provided on the lathe  10  for operating the motor  14  to drive the workpiece. 
         [0028]    In a typical lathe, and in other power tools, the motor is provided with a drive pulley which drives a belt which engages a driven pulley which drives the first center member  16 . The motor is attached to a pivoting plate  23  which includes a handle or other grasping provision and can be held in various positions by a clamping device. The user releases the clamp and manually raises or lowers the pivoting plate  23  to release or apply tension to the drive belt and clamps it in the desired position. 
         [0029]    The present disclosure is directed to several belt tensioning devices and release mechanisms for a lathe or other power tools devices (for example, drill press) utilizing a drive belt. In each of the disclosed belt tensioning devices ( FIGS. 2-11 ), a motor  14  is provided with a driveshaft  24  connected to a drive pulley  26  that drives a belt  28  that is connected to a driven pulley  30  that is connected to the center member  16  for turning the workpiece. 
         [0030]    With particular reference to FIGS.  2  and  3 A- 3 C, a belt tensioning device includes a pivot member in the form of a mounting plate  34  that can be pivotally mounted to a pivot point  36  which can be mounted to the support structure  12  of the lathe  10 . The motor  14  can be mounted to the pivot member  34  such as by fasteners  38  or, alternatively, the pivot member can be integral to the motor  14 . A lever arm  40  can be pivotally mounted to the support structure  12  of the lathe  10  by a pivot point  42 . The lever arm  40  can be connected to the pivot member  34  by a link  44 , or alternatively, by a linkage system, direct connection or other known connection device. The lever arm  40  and link  44  can be constructed or arranged such that when the lever arm  40  is pivoted to apply tension to the belt  28 , it rotates past a dead-center position as shown in  FIG. 3A , and comes to rest against a stopping feature either affixed or integral to the support structure  12 , thereby locking into place. An adjustment can be provided to the link  44 , such as a threaded portion of the link  44  in conjunction with a thumb wheel nut  46 , so as to allow the length of the link  44  to be varied, thereby increasing or decreasing the amount of tension applied to the belt  28  when the lever arm  40  is in the locked position. The user can release the tension on the belt  28  by rotating the lever arm  40  past the dead-center locking position and pressing downward as illustrated by arrow A, wherein the pivot member  34  is rotated in the direction of arrow B which causes the drive pulley  26  to move in an upward direction toward the fixed driven pulley  30  in order to release the tension on the belt  28  to allow the belt  28  to be re-positioned or replaced as necessary. A latching device, such as a locking tab  48 , can be provided for engaging the lever arm in the tension released position so that the operator has two hands free to adjust or change the belt. As shown in  FIG. 3C , the locking tab  48  can be a spring arm that has a cam surface  48   a  that pushes the tab  48  inward as the lever arm  40  is pivoted to the tension release position illustrated in  FIGS. 2 ,  3 B and  3 C. The tab  48  includes a locking finger  48 B that engages the lever arm  40 . 
         [0031]    With reference to  FIGS. 4-6 , an alternative belt tensioning device according to the principles of the present disclosure will now be described. In the belt tensioning device as illustrated in  FIGS. 4-6 , the motor  14  is mounted to a pivot member  134  such as a motor mounting plate. The pivot member  134  is pivotally mounted to a pivot point  36  which can be mounted to the support structure  12  of the lathe  10 . The pivot member  134  includes an elongated slot  50  that can be provided on an ear  52  extending from the pivot member  134 . A lever arm  54  can be pivotally mounted to the support structure  12  at pivot point  56  and can include an engagement pin  58  which is received in the elongated slot  50  of the pivot member  134 . A spring  60  can be disposed between the pivot member  134  and the support structure  12  to provide a downward force against the pivot member  134  as illustrated by arrow C as shown in  FIG. 6 . The spring  60  applies a downward force on the pivot member  134  which provides additional tension on the belt  28 . In addition, the weight of the motor  14  also provides tension on the belt  28  to prevent slippage thereof. The operator can press downward on the lever arm  54  in order to cause the lever arm  54  to pivot about pivot point  56  causing the pin member  58  to lift upward on the pivot member  134  causing the drive pulley  26  and motor  14  to lift upward toward the driven pulley  30  thus reducing the tension on the belt  28  to allow the belt  28  to be adjusted or replaced. A latch device can be provided to releasably secure the lever arm in the tension release position, freeing up both hands of the operator to adjust or change the belt  28 . 
         [0032]    With reference to  FIGS. 7 and 8 , a still further belt tensioning device will now be described. With particular reference to  FIG. 8 , the device includes a pivot member  234  that can be mounted to the support structure  12  of the lathe  10  at pivot point  36 . The pivot member  234  can include an elongated slot  70  that is disposed on an opposite side of the motor  14  from the pivot point  36 . The slot  70  is engaged by a pin  72  which is attached to a pull knob device  74 . The pull knob device  74  is provided with a bias spring  76  which biases the pull knob  74  in the direction of arrow D ( FIG. 8 ). When the pull knob device  74  is pulled against the biasing force of the spring  76 , in the direction of the arrow E ( FIGS. 7C and 8 ), the drive pin  72  pulls against the pivot member  234 , causing the pivot member  234  to rotate in the direction of arrow F causing the motor  14  and drive pulley  26  to move in an upward direction toward driven pulley  30  thus reducing the tension on belt  28 . The spring  76  as well as the motor  14  apply forces to the pivot member  234  causing the pivot member  234  to rotate in a direction opposite to arrow F thus causing tension to be applied to belt  28 . The pull knob  74  can be provided with a latch device for engaging the pull knob  74  in the tension release position so that the operator has two hands free to adjust or change the belt. 
         [0033]    With reference to  FIG. 7E , the pull knob device  74  includes a guide sleeve  240  having an aperture  242  extending therethrough. The aperture  242  includes at least one flat wall portion  244 . An end  246  of the guide sleeve is provided with a pair of elongated slots  248 . A pin rod  250  is received in the aperture  242  of the guide sleeve  240  and includes at least one slide portion  252  having at least one flat wall  254  to engage the at least one flat wall portion  244  of the guide sleeve  240  to prevent relative rotation therebetween. The pin rod  250  has a transverse aperture  256  for fixedly supporting drive pin  72  therein. The pin rod  250  also includes a cylindrical rod portion  258  extending form the slide portion  252 . A handle shaft  260  is provided with a circular aperture  262  for receiving the cylindrical rod portion  258  therein. The handle shaft  260  is non-rotatably fixed to a handle  264  and includes at least one flat wall  266 , similar to the slide portion  252 . A washer  268  and retaining clip  270  secure the handle shaft  260  rotatably on the pin rod  250 . In the assembled condition as illustrated in  FIG. 7C , a pair of washers  272 ,  274  retain the spring  76  on the guide sleeve  240  between an end flange  276  of the guide sleeve  240  and the drive pin  72  which is received in the pin rod  250 . When the hand  264  is pulled to the position shown in  FIG. 7C , the handle shaft  260  is fully removed from the aperture  242  of the guide sleeve  240  and is therefore free to rotate relative to the guidesleeve. By rotating the handle  264  and handle shaft to the position shown in  FIGS. 7C ,  7 D, the flat  266  on the handle shaft is misaligned with the flat wall portion  244  and the handle shaft is not permitted to return to the position shown in  FIGS. 7A and 7B  until the handleshaft is rotated so that the flat  266  aligns with the flat wall portion  244 . Thus, the user is free to use both hands to adjust or change the belt  28 . 
         [0034]    With reference to  FIGS. 9 and 10 , a still further belt tensioning device will now be described. The belt tensioning device includes a pivot member  334  to which the motor  14  is mounted. The pivot member  334  is mounted to a pivot point  36  which can be provided on the support structure  12  of the lathe  10 . The pivot member  334  includes a cam follower surface  80  which rests against a cam member  82 . The cam member  82  is supported by a shaft  84  which can be rotated to cause cam member  82  to lift upward on the cam follower surface  80  of the pivot member  334  thus causing the pivot member  334  to rotate in the direction of arrow G as illustrated in  FIG. 10 . When the pivot member  334  rotates in the direction of arrow G, the motor  14  and drive pulley  26  are moved in an upward direction toward driven pulley  30 , thus reducing the tension on belt  28 . With the tension on the belt  28  released, the belt  28  can be replaced or adjusted. A torsion spring  90  can be mounted to the shaft  84  which is connected to the cam member  82  and the torsion spring  90  can apply a downward force against the pivot member  334  or motor  14  apply a downward force tending to cause the pivot member  334  to rotate in a direction opposite arrow G and thus applying tension to the belt  28  along with the weight of the motor  14 . 
         [0035]    With reference to  FIGS. 11 and 12 , a still further belt tensioning device will now be described. With reference to  FIG. 11 , an idler pulley  400  is provided for applying tension to the belt  28 . The idler pulley  400  is supported by a arm structure  402  which is pivotally mounted to the support structure  12  of lathe  10 . The arm structure  402  can have a generally u-shape with opposite ears  404  which are received in apertures  406  provided in the support structure  12 . The idler pulley  400  is supported on the arm  402  by bearing members  410 . A torsion spring  412  can be provided for biasing the idler pulley  400  toward the belt  28  in order to tension the belt  28  between the drive pulley  26  and driven pulley  30 . A handle  416  is connected to the arm member  402  to allow a user to pivot the arm member  402  so that the pulley  400  can be moved away from the belt  28  to reduce tension on the belt  28  to allow the belt to be either changed or adjusted.