Patent Application
20120141217
1. Field of the Invention
The present invention generally relates to drill presses and more specifically relates to depth scales for drill presses.
2. Description of the Related Art
Drill presses are used for drilling holes in work pieces such as sheet metal and wood. Typically, a drill press includes a work piece supporting table that is used to stabilize work pieces during drilling operations, and to insure that the work pieces are aligned with a rotating drill bit for accurately drilling holes in the work pieces.
Many drill presses have depth stops and/or depth scales that control how far a rotating drill bit may be lowered into a work piece. For example, U.S. Pat. No. 5,096,340 to Forsgren discloses a drill press having a quick-adjust depth scale. The quick adjust-depth scale includes a handle clamp assembly whereby the clamp has an opening in which a cylindrical shaft with suitable depth measurement markings thereon is received. Turning the handle on the clamp enables the depth scale to be set to a desired depth.
U.S. Pat. No. 5,577,868 to Chen discloses a depth stop for a drill press including a block having a central passage and a cut-away laterally defined therein that communicates with the central passage. The depth stop includes an oblong element received in the cut-away and a resilient element disposed between the oblong element and the block. The oblong element has an oblong hole defined therein and has a threaded portion defined on an inner periphery of the oblong hole for engagement with a threaded rod that extends through the central passage of the block and the oblong hole of the oblong element. The block is freely moveable along the threaded rod by depressing the oblong element to compress the resilient element and disengage the threaded portion of the oblong element from the threaded rod.
In spite of the above advances, there remains a need for improved depth stops and/or depth scales for drill presses. In particular, there remains a need for a zeroable depth scale for a drill press that enables operators to efficiently and accurately position a drill bit on top of a work piece and zero the scale and select a desired drilling depth without requiring the operator to perform mathematical calculations from a fixed depth scale.
In one embodiment, a drill press having a zeroable depth scale preferably includes a head stock mounted atop a support column, a pinion shaft rotatable about a horizontal axis extending through the head stock, the pinion shaft having an outer end that extends through a side wall of the head stock, and a quill coupled with the pinion shaft and projecting from a bottom of the head stock along a vertical axis. The drill press desirably includes a pinion shaft hub connected with the outer end of the pinion shaft and being located adjacent the side wall of the head stock. The pinion shaft hub is preferably rotatable for rotating the pinion shaft about the horizontal axis, which, in turn, provides reciprocating movement to the quill along the vertical axis. The drill press desirably includes a stationary zeroing element mounted on the head stock and disposed between the side wall of the head stock and the pinion shaft hub, and a depth scale mounted on the pinion shaft hub adjacent the stationary zeroing element. The depth scale and the pinion shaft hub are preferably frictionally coupled together so that the depth scale normally rotates simultaneously with the pinion shaft hub, however, the depth scale is rotatable relative to the pinion shaft hub upon exceeding a friction force that normally resists movement of the depth scale relative to the pinion shaft hub.
In one embodiment, the pinion shaft hub desirably has an inner section including an annular groove and an outer section having at least one anchor point for a pinion shaft handle. The depth scale may be frictionally coupled with the annular groove of the pinion shaft hub. The depth scale preferably has a ring shape and is frictionally coupled with the annular groove of the pinion shaft hub.
In one embodiment, the depth scale preferably has depth measuring indicia located adjacent the stationary zeroing element. The stationary zeroing element may include a stationary ring having a zero marker mounted on the side wall of the head stock. The pinion shaft desirably extends through the stationary ring. In one embodiment, upon overcoming the friction force, the depth scale is rotatable relative to the pinion shaft hub for aligning one of the depth measuring indicia of the depth scale with the zero marker of the stationary ring. In one embodiment, the depth scale has a depth measuring indicator identified as “zero” that is aligned with the zero marker on the stationary ring for zeroing the depth scale.
In one embodiment, the drill press desirably includes a quill bracket connected with the quill, the quill bracket including a quill bracket opening, and a stop bracket connected with the head stock, the stop bracket including a stop bracket opening that is vertically aligned with the quill bracket opening. The drill press preferably has a rod having an upper end, a lower end, and a length extending between the upper and lower ends thereof. The rod extends through the quill bracket opening and the stop bracket opening and the lower end of the rod is desirably connected with the quill bracket. A lower locking element is mounted on the rod and is lockable at a plurality of locations along the length of the rod between the quill bracket and the stop bracket, and an upper locking element is mounted on the rod and is lockable at a plurality of locations along the length of the rod between the stop bracket and the upper end of the rod.
In one embodiment, the quill bracket is adapted to move simultaneously with the quill as the quill moves along the vertical axis. The quill bracket is preferably adapted to move relative to the stop bracket as the quill moves along the vertical axis.
In one embodiment, the rod desirably has an outer surface including external threads, and the lower and upper locking elements have central apertures including internal threads that are adapted to mesh with the external threads of the rod. At least one of the locking elements preferably includes a biased element that is depressible for decoupling the internal threads of the at least one of the locking elements from the external threads of the rod for enabling the at least one of the locking elements to slide over the external threads of the rod. When the biased element is not depressed, at least one of the locking elements is rotatable about the rod for moving the at least one of the locking elements between the upper and lower ends of the rod.
In one embodiment, a drill press having a zeroable depth scale preferably includes a support column having an upper end and a lower end, a head stock connected to the upper end of the support column, a base connected to the lower end of the support column, and a work piece supporting table coupled with the support column. The drill press desirably includes a pinion shaft having an outer end extending through a side wall of the head stock, a quill coupled with the pinion shaft and projecting along a vertical axis from a bottom of the head stock, a spindle connected with the quill and projecting along the vertical axis from a lower end of the quill, a chuck connected with the spindle and projecting along the vertical axis from a lower end of the spindle, and a drill bit connected with the chuck and projecting along the vertical axis from a lower end of the chuck.
The drill press may include a pinion shaft hub coupled with the outer end of the pinion shaft and being located adjacent the side wall of the head stock, whereby the pinion shaft hub is rotatable for rotating the pinion shaft, which, in turn, provides reciprocating movement to the quill, the spindle, the chuck, and the drill bit along the vertical axis. A stationary zeroing element is desirably mounted on the head stock and disposed between the side wall of the head stock and the pinion shaft hub, and a depth scale mounted on the pinion shaft hub adjacent the stationary zeroing element, the depth scale frictionally coupled to the pinion shaft hub so that the depth scale normally moves simultaneously with the pinion shaft hub. The depth scale is moveable relative to the pinion shaft hub upon exceeding a friction force that normally resists movement of the depth scale relative to the pinion shaft hub.
In one embodiment, the pinion shaft hub preferably has an inner section including an annular groove and an outer section having at least one anchor point for a pinion shaft handle. The depth scale preferably has a ring shape and is frictionally coupled about the annular groove of the pinion shaft hub. The depth scale desirably has depth measuring indicia located adjacent the stationary zeroing element, the stationary zeroing element includes a stationary ring having a zero marker and the pinion shaft extends through the stationary ring. Upon the depth scale overcoming the friction force, the depth measuring indicia is alignable with the zero marker.
In one embodiment, a method of zeroing a drill press desirably includes rotating the pinion shaft hub for lowering the drill bit until it touches a work piece overlying the work piece supporting table, moving the lower locking element toward the upper end of the rod until the lower locking element abuts against a bottom surface of the stop bracket, rotating the depth scale on the pinion shaft hub so that a zero indicator on the depth scale is aligned with the zero marker of the stationary ring, and removing the work piece from the work piece supporting table and rotating the pinion shaft hub to lower the drill bit to a desired drilling depth as indicated by the depth measuring indicia of the depth scale.
In one embodiment, the method may include while maintaining the drill bit at the desired drilling depth, moving the lower locking element toward the upper end of the rod until the lower locking element engages the bottom surface of the stop bracket, while still maintaining the drill bit at the desired drilling depth, lowering the upper locking element toward the lower end of the rod until the upper locking element engages the top surface of the stop bracket, and moving the lower locking element away from the stop bracket.
These and other preferred embodiments of the present invention will be described in more detail below.
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The drill press 20 desirably includes a table 36 having a top surface 38 adapted to support work pieces. The table 36 is preferably coupled with the vertical support column 24. The table may be moved up and down the support column 24 by cranking a table handle 40 that is coupled with a rack and pinion structure (not shown). In one embodiment, the table 36 may be rotated about the support column 24, or placed at a non-perpendicular angle relative to the longitudinal axis A2 of the support column. When positioned atop the table 36, the work pieces are preferably aligned with the drill bit 34 for drilling holes in the work pieces.
The drill press 20 preferably includes a pinion shaft for providing reciprocating movement of the quill 28 along the vertical axis A1. In one embodiment, the drill press 20 includes a pinion shaft hub 42 that is mounted on a rotatable pinion shaft (not shown) that extends horizontally through the head stock 22. Pinion shaft handles 44A-44C are secured to the pinion shaft hub 42. The pinion shaft is coupled with the quill 28 so that as an operator turns the pinion shaft hub 42 using the pinion shaft handles 44A-44C, the quill 28 will move up or down along the vertical axis A1. This vertical motion may be used to advance the drill bit 34 into drilling engagement with a work piece supported over the top surface 38 of the table 36.
The drill press 20 preferably includes a zeroable depth scale that is used for controlling the depth of holes drilled into work pieces. In one embodiment, the zeroable depth scale desirably includes a rotatable ring that is mounted on the pinion shaft hub 42. The rotatable ring preferably has a scale for measuring, selecting and setting drilling depths. The rotatable ring is frictionally coupled with the pinion shaft hub 42 so that it may be selectively rotated relative to the pinion shaft hub only after overcoming a friction force that normally resists movement between the depth scale ring and the pinion shaft hub. The pinion shaft hub 42 preferably has an outer surface having at least one anchor point 46 for receiving a pinion shaft handle.
In one embodiment, the drill press 20 desirably includes a quill bracket 52 having a first end 54 mounted to the quill 28 and a second end 56 having a quill bracket opening 58 extending therethrough. The quill bracket 52 preferably moves simultaneously with the quill 28. The drill press preferably includes a stop bracket 60 that is secured to the head stock 22. The stop bracket 60 preferably includes a stop flange 62 connected therewith having a stop bracket opening 64 extending therethrough that is preferably vertically aligned with the quill bracket opening 58. As the quill 28 moves upwardly along the vertical axis A1, the quill bracket 52 preferably moves toward the stop bracket 60. As the quill 28 moves downwardly along the vertical axis A1, the quill bracket 52 preferably moves away from the stop bracket 60.
The drill press preferably includes a threaded rod 66 that extends through the quill bracket opening 58 in the quill bracket 52 and the stop bracket opening 64 in the stop flange 62 of the stop bracket 60. In one embodiment, the threaded rod 66 desirably extends along a vertical axis that is parallel with the vertical axis A1. The threaded rod 66 desirably has an outer surface having external threads 68 formed thereon. In one embodiment, the external threads are desirably helically wound about the threaded rod 66. A fastener 70, such as a locking nut 70, desirably connects a lower end of the threaded rod 66 with the quill bracket 52 so that the quill bracket 52 and the threaded rod 66 may move simultaneously with one another.
The drill press also desirably includes a lower locking element 72 that has internal threads that mesh with the external threads 68 on the threaded rod 66. The lower locking element 72 preferably includes a depressable button 74 that may be pressed for decoupling the internal threads of the lower locking element 72 from the external threads 68 of the threaded rod 66 so that the lower locking element 72 may slide over external threads 68 for quickly adjusting the position of the lower locking element 72 relative to the threaded rod 66. When the button 74 is not depressed, the internal threads of the lower locking element engage the external threads of the threaded rod so that the lower locking element 72 may only be raised and lowered on the rod by rotation of the lower locking element 72.
The drill press also preferably includes an upper locking element 76 that has internal threads that engage the external threads 68 of the threaded rod 66. The upper locking element 76 desirably has a depressable button 78 that may be pressed for decoupling the internal threads of the upper locking element 76 from the external threads 68 of the threaded rod 66 so that the upper locking element 76 may slide over external threads 68 for quickly adjusting the position of the upper locking element 76 relative to the threaded rod 66. When the button 78 is not depressed, the internal threads of the upper locking element 76 engage the external threads of the threaded rod so that the upper locking element may only be raised and lowered on the rod by rotation of the upper locking element 76.
In one embodiment, the upper and lower locking elements 72, 76 may be rotated about the threaded rod 66 for making micro-adjustments of the upper and lower locking elements 72, 76 along a longitudinal axis of the threaded rod 66. The depressable buttons 74, 78 of the respective upper and lower locking elements 72, 76 may be depressed for decoupling the inner threads of the respective upper and lower locking elements from the threaded rod for making gross adjustments of the upper and lower locking elements along the longitudinal axis of the threaded rod 66.
The stop bracket 60 is permanently attached to the head stock 22 and does not move relative to the head stock. The quill bracket 52 is permanently attached to the quill 28 and moves up and down with the quill along the vertical axis A1. As the quill 28 moves up and down along the vertical axis A1, the quill bracket 52 moves simultaneously with the quill and moves relative to the stop bracket 60.
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The operator may then remove the work piece 50 and rotate the pinion shaft handles 44A-44C to lower the quill 28 to a desired drilling depth as indicated by the scale markings 92 on the depth scale 90. While holding the quill 28 at the desired drilling depth, the operator preferably depresses the button 74 on the lower locking element 72 and raises the lower locking element 72 until it abuts against the bottom surface of the stop flange 62 of the stop bracket 60. While the quill 28 is held at this depth by the lower locking element 72, the operator preferably presses the button 78 on the upper locking element 76 and lowers the upper locking element 76 down against a top surface of the stop flange 62 of the stop bracket 60. The upper locking element has now been positioned at a location on the threaded rod that will stop the drill bit 34 from advancing beyond the desired drilling depth for drilling into the work piece 50. The operator may move the lower locking element 72 away from the stop flange 62.
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The present invention enables operators to efficiently and accurately measure a drilling depth, establish a desired drilling depth, and zero the scale on a depth scale without requiring calculations from a fixed depth scale. The advantages include that a user is able to position a depth scale including a rotatable ring over a smooth surface without coming into contact with sharp pointers and without requiring the user to make mathematical calculations, which could lead to errors.
The headings used herein are for organizational purposes only and are not meant to limit the scope of the description or the claims. As used throughout this application, the word “may” is used in a permissive sense (i.e., meaning having the potential to), rather than the mandatory sense (i.e., meaning must). Similarly, the words “include”, “including”, and “includes” mean including but not limited to. To facilitate understanding, like reference numerals have been used, where possible, to designate like elements common to the figures.
While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, which is only limited by the scope of the claims that follow. For example, the present invention contemplates that any of the features shown in any of the embodiments described herein, or incorporated by reference herein, may be incorporated with any of the features shown in any of the other embodiments described herein, or incorporated by reference herein, and still fall within the scope of the present invention.
