Abstract:
A frame for a portable power sander, the frame convertible into a stand for supporting the power sander in a stationary orientation wherein the abrasive belt is accessible, said frame comprising: a base; a leg connectable to the base, and a fence assembly connectable to the base.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention generally relates to electric powered portable sanders. More particularly it relates to an accessory for a portable sander that is convertible between a sander frame and a sander stand. As a frame, it supports or stabilises a portable belt sander as the user moves the sander over a wooden workpiece. As a stand, it supports the sander in an orientation wherein the sander&#39;s abrasive belt is exposed so that the user may manipulate a workpiece against the moving abrasive belt.  
       BACKGROUND OF THE INVENTION  
       [0002]     A belt sander may be employed with either a sanding frame/shoe or an inversion stand.  
         [0003]     Sanding frames are generally well known. Sander frames are used to expand the footprint or base of the sander on the workpiece below. When a belt sander is mounted in such a frame, the sander is stabilised for movement over the surface of the workpiece. If the user applies uneven or unbalanced levels of force to the sander&#39;s handle(s) then the frame/shoe will prevent the sander from tipping and/or gouging the work piece surface. Additionally, many sanding frames contain means for adjusting the depth-of-cut of the sander mounted within the rigid frame. With such a mechanism the user can adjust the amount of wood removed by the sander as it is passed over the workpiece.  
         [0004]     Sander stands are also generally known. A so called “inversion stand” is an accessory that provides a fixed frame/base for holding the belt sander in an orientation on its side or inverted so that the abrasive belt is exposed for access by the user. Thus supported, the portable sander becomes a bench tool and the user can pass a piece of wood over the moving belt, or press and manipulate a workpiece against the moving belt. Inversion stands sometimes are provided with a table or fence to support and/or align the workpiece while it is slid over the sander belt.  
         [0005]     Sander stands and frames are provided as two different accessories. They add to the bulk and weight of equipment the tradesman must transport to the work site. The stand, in particular, is intended for stationary use and current models are not very portable.  
       SUMMARY OF THE INVENTION  
       [0006]     It is proposed to provide an accessory sanding frame that can be converted into an inversion frame by the addition of legs, which can be attached to the frame so as to support the sander in one of multiple possible orientations.  
         [0007]     An advantage of such an adaptable accessory is that the sander frame performs double duty by serving as the mounting point for the sander in both the mobile frame role and fixed stand role. Savings are achieved in cost, weight, and storage volume.  
         [0008]     A further advantage of the subject invention is that&#39;s since the sanding frame has a depth of cut adjustment, that capability will also be present in the fixed stand.  
         [0009]     A still further advantage of the subject frame/stand is the provision of a particularly economical and easy to manufacture hinge structure for pivoting adjustment of the sander within the frame, and thus of the sanders depth of cut. Said hinges comprising an open recess in the frame, a bearing element of simple geometry and defining a cylindrical bore, and a retainer piece for holding the bearing in the recess.  
         [0010]     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating a preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]     A sander according to the present invention will now be described by way of example, with reference to the accompanying drawings in which:  
         [0012]      FIG. 1  perspective view of a belt sander mounted in a frame according to the present invention.  
         [0013]      FIG. 2  is an alternative perspective view of a belt sander mounted in the frame of  FIG. 1 .  
         [0014]      FIG. 3  is a top perspective view of a belt sander mounted in the frame of  FIG. 1 .  
         [0015]      FIG. 4  is a perspective view of a belt sander mounted in the frame of  FIG. 1  converted into a stand.  
         [0016]      FIG. 5  is a side perspective view of a belt sander mounted in the stand of  FIG. 4 .  
         [0017]      FIG. 6  is a perspective view of a belt sander mounted in the stand of  FIG. 4  at an alternative orientation.  
         [0018]      FIG. 7  is an alternative perspective view of the belt sander and stand of  FIG. 6 .  
         [0019]      FIG. 8  is a perspective view of the sander frame of  FIG. 1 .  
         [0020]      FIG. 9  is an alternative perspective view of the sander frame of  FIG. 8 .  
         [0021]      FIG. 10  is a close-up perspective view of the depth-of-cut mechanism of the sander frame of  FIG. 9 .  
         [0022]      FIG. 11  is the close-up perspective view  FIG. 10  with some elements of the depth of cut mechanism shown in see-through/phantom.  
         [0023]      FIG. 12  is a further close up of one hinge of the depth-of-cut mechanism of  FIG. 11 .  
         [0024]      FIG. 13  is the same view as  FIG. 12  without the see through phantoming.  
         [0025]      FIG. 14  close up perspective view of elements of the hinge structure of  FIG. 12 . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0026]     With reference to the attached  FIGS. 1 , sander frame  20  consists of a base  22  defining an opening  24 . In the preferred embodiment shown both base  22  and opening  24  are substantially rectangular. Base  22  has a first lower surface  23  and a second upper surface  25 . First lower surface  23  is preferably finished or coated to move smoothly over the surface of a wooden workpiece.  
         [0027]     A forward rod assembly  30  and a rearward rod assembly  32  are pivotally connected to the base  22  across opening  24  and proximate to their respective ends of the base. Forward rod assembly  30  is comprised of forward rod  31  and two hinge assemblies  40 , and rear rod assembly  32  is comprised of rear rod  33  and two more hinge assemblies  40 .  
         [0028]     Connected to and pivoting with forward rod  31  is a mounting plate  34 . Rotateably mounted within mounting plate  34  is threaded screw  36 , which is turned by knob  38 .  
         [0029]     A depth-of-cut adjustment mechanism  60  is mounted to frame  22  and connected to forward rod  31  for pivoting the forward rod assembly  30 . Adjustment of depth of cut mechanism  60  causes forward rod  31  to pivot upward and forward and out of the plane of the base  22 , or rearward and downward into the plane of the base  22 .  
         [0030]     With reference to  FIGS. 2-5 , a particularly easy to manufacture and thus economical structure for hinge assemblies  40  will now be described. Near the corners of opening  24 , recesses  41  are defined by the base  22 . For ease of manufacturing, the recesses  41  are open toward the upper face  25  of frame base  22 . Furthermore, each recess  41  is of relatively simple geometry. Preferably, it may be a simple rectangle or a semicylindrical shape or a combination thereof.  
         [0031]     In the recess  41  is located a bearing  42 . Bearing  42  may also be of a simple external geometry selected to conform to the recess  41 . Bearing  42  defines a bore  43 . Rotatably mounted in bore  43  is the first or outer end  48  of pivot pin  44 . The second or inner end  49  of pivot pin  44  is connected to a first end  50  of pivot arm  45 . The second end  51  of each pivot arm  45  is connected to either rod  31  or  33 .  
         [0032]     Bearing element  42  is captured in recess  41  by a retainer. In the preferred embodiment shown, retainer plate  46  covers the top of recess  41  and is secured to the base  22  by a machine screw  47 . On the face of recess  41  towards the opening  24 , a lip  28  of the base  22  also serves to retain the bearing element  42 .  
         [0033]     Now with reference to  FIGS. 6-8 , the sander  10  (some structural elements of the sander are omitted for clarity and an improved view of the subject frame/stand) is shown mounted in frame  20 . Sander  10  is connected to the pivotable rods  31  and  33  so that the sander can be raised or lowered relative to the base  22  for adjustment of the depth-of-cut. At its rear end, the sander housing  12  has clips  14  that clasp the rear pivot rod  33 . At the front end of the sander housing  12 , a hole  16  (not shown, but the same hole used to mount the auxiliary handle in its forward optional position) receives threaded screw  36 . Knob  38  is used to tighten screw  36  and pull housing  12  against mounting plate  34 .  
         [0034]     With particular reference to  FIG. 9 , the depth of cut adjustment mechanism  60  will now be described. Mounted to frame base  22  is a yoke assembly  26 . Yoke  26  defines a bore  27  (not shown). Front rod  31  passes through a collar  62 . A threaded rod  64  having a first end  63  and a second end  64  is attached to the collar  62  at the first end  63 . Threaded rod  64  extends through the bore  27  of yoke  26  and is threadably engaged by a knob  68  at the second end  64 . A biasing spring  66  is mounted co-axially around the threaded rod  64  between collar  62  and yoke  26 . Spring  66  acts to push the collar  62  and thus rod  31  downward into the lowered position. A user can turn knob  68  to pull the collar  62  and thus the forward rod  31  upward into a raised position, against the force of spring  66 .  
         [0035]     With the sander  10  connected between the forward rod  31  and the rear rod  33  (as described above), movement of the forward rod  31  is transmitted to the rear rod  33  and produces an identical pivoting movement. Thus, as the rods  31  and  33  pivot, the sander  10  moves in a arcuate path that raises or lowers the sander within the opening  24  while maintaining the sander&#39;s abrasive surface  18  planar parallel with the frame base  22 , and thus to the workpiece.  
         [0036]     With reference now to  FIGS. 10-13 , the sander frame can be converted into an inversion stand  70  by the addition of two legs  72  and a fence assembly  80 . The legs  72  are secured to the base  22  by screws  74 . Legs  72  may be connected to base  22  to achieve either a vertical orientation as in  FIG. 10  or a horizontal orientation as in  FIG. 12 , wherein base  22  is substantially perpendicular to the ground. Alternatively, legs could be used to support the base  22  in an inverted orientation substantially planar parallel relation to the ground, and wherein first/lower surface  23  and the abrasive belt face upward.  
         [0037]     Fence assembly  80  can be secured to base  22  by screws  83  in either of two positions complementary to the chosen orientation of the sander. Fence assembly  80  comprises a fixed element  82  and an angularly adjustable table  84 , which may secured with nut  86  at the desired angle relative to the plane of the base  22 .  
         [0038]     Fence assembly  80  also includes a guard piece  81 . As seen in  FIG. 12 , when the sander  10  is in the horizontal orientation, guard  81  is located adjacent to the abrasive belt and covers the gap between the rear of roller/belt  18  and the sander housing  12  in order to prevent a small/thin workpiece from being dragged into that gap by the movement of the belt  18 . In the vertical orientation, the table  86  is directly in the path of the belt  18  and a separate guard is not required.  
         [0039]     The above-described depth of cut adjustment of the sander  10  in the sander frame  20  permits the user to move the sander belt  18  towards and away from the table  84 . This is particularly advantageous since the pivoting movement of the table  84  can open up a gap between the belt  18  and the table, and a small/thin work piece could be dragged into that gap by the movement of the belt.  
         [0040]     While the invention has been described in the specification and illustrated in the drawings with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention as defined in the claims. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment illustrated by the drawings and described in the specification as the best mode presently contemplated for carrying out this invention, but that the invention will include any embodiments falling within the foregoing description and the appended claims.