1. Field of the Disclosure
The present disclosure relates generally to a mandrel assembly adapted to attach a hole saw and a pilot drill bit to an electric drill. More particularly, the present disclosure relates to such a mandrel assembly that is designed and operated to have a “self-clearing” feature.
2. Background of the Disclosure
Many designs for a mandrel assembly for a hole saw and drill bit combination are known in the art. Representative publications showing such mandrel assemblies are U.S. Pat. No. 5,246,317 and EP Pub. 1462198. By way of general design, known mandrel assemblies have several parts in common. All assemblies have a pilot bit and a hole saw, in which the pilot bit serves the purpose of guiding the hole saw to the proper location in the workpiece. Also, known mandrel assemblies generally include a base mechanism and an adapter. In general terms, the base mechanism is designed for attachment to the chuck of, e.g., an electric drill, while the adapter is designed for mounting the hole saw/pilot bit combination to the base mechanism.
Regardless of design, a shortcoming of the prior art mandrel assemblies is that the “plug” of the workpiece cut out by the hole saw remains behind in the interior space of the hole saw and must be removed before the hole saw can be used to cut a new hole in the workpiece. Removal of the “plug” often entails removal of the mandrel from the electric drill and the use of an implement of some sort to remove the “plug” from the interior space of the hole saw. Generally speaking, the mandrel is removed from the chuck of the electric drill to simplify access to the “plug” remaining in the interior space of the hole saw, as well as to ensure the safety of the operator. Removing the mandrel from the electric drill is time-consuming, preventing the operator from proceeding to cut the next hole in the same or another workpiece. Coupled with the foregoing time delay is the additional delay caused by the need to remove the “plug” and to reinstall the mandrel into the chuck of electric drill.
Thus, a need exists for a mandrel that allows removal of the “plug” material from the interior space of the hole saw to be effected quickly and safely, without the need to remove the mandrel from the electric drill, and without the need to employ an additional implement, to remove the “plug”.
The present disclosure solves the above-mentioned need by providing a mandrel assembly with a “self-clearing” feature, namely to quickly and safely remove the “plug” (i.e., the cut portion of a workpiece) contained within the hole saw resulting from the action of the hole saw drilling through the workpiece.
The present disclosure also provides the self-clearing feature without removing the mandrel assembly from the drill chuck.
The present disclosure further provides the self-clearing feature without the need to employ an additional implement to remove the “plug”.
In one embodiment of the present disclosure, a mandrel assembly is provided that comprises: a threaded shaft comprised of a first end and a second end, the first end including a chamfered end for being held in a drill chuck, the second end comprising a threaded portion for matingly receiving a hole saw; the hole saw comprised of a base disposed toward the chamfered end, the base having at least one opening disposed therethrough and at least one movable rod that matingly engages the at least one opening, the movable rod disposed substantially parallel to the threaded shaft between the chamfered end and the base.
The mandrel assembly of the present disclosure will now be described in more detail with reference to the Figures.
In the detailed description of the preferred embodiment that follows, like numerals are used to designate like elements throughout the description of the Figures, although alternatives will be apparent to one of skill in the art based on the following detailed description.
Referring to
Base mechanism 160 has a proximal end 161 and a chamfered end 162. Proximal end 161 is disposed in relation to base 125 of hole saw 120 so as to receive a chamfered end 182 of adapter 180 (see,
Referring to
Once plug 370 is ejected from inside diameter 121 of hole saw 120, mandrel assembly 300 is returned to “cutting” position as follows. While still grasping knurled knobs 350 and 351, operator reverses the rotation of drill chuck once again, so that drill chuck and mandrel assembly 300 are again rotated in a clockwise direction. As drill chuck rotates clockwise, threaded shaft 310 is urged forward through knurled knobs 350 and 351, and ejection rods 340 are pulled back from the inside space of hole saw 120, so that ends 341 of ejection rods 340 no longer reside in the inside space of hole saw 120. Rather, ends 341 of ejection rods 340 are returned to their cutting position flush, or substantially flush, with inside surface 127 of bottom 125 of hole saw 120. Knurled knob 352 serves to act as a “stop” so that knurled knobs 350 and 351, grasped by the operator cannot be retracted such that ejection rods 340 are pulled below or substantially below openings 380 in base 125 of hole saw 120. Knurled knob 352 acts as a “safety” device, ensuring that alignment of ejection rods 340 with pilot bit attachment/ejection rod guide collar 330 and openings 380 in base 125 is maintained.
Assembly of mandrel assembly 300 can be performed in various ways. Beginning with threaded shaft 310, pilot bit attachment/ejection rod guide collar 330 is placed on threaded shaft 310 (either by threading onto threaded shaft 310 or by having an inside diameter slightly greater than the diameter of threaded shaft 310 and sliding onto threaded shaft 310). Pilot bit attachment/ejection rod guide collar 330 can be held in place on threaded shaft 310 by use of a set screw. A sufficient amount of threaded shaft 310 is left exposed so that hole saw 120 can be threaded onto threaded shaft 310 and placed into communicative relation with pilot bit attachment/ejection rod guide collar 330. Preferably, the amount of threaded shaft 310 left exposed is such that when hole saw 120 is fully threaded onto threaded shaft 310, openings 380 in base 125 of hole saw 120 align with channels 360 of pilot bit attachment/ejection rod guide collar 330. In this embodiment, both hole saw 120 and pilot bit attachment/ejection rod guide collar 330 can be threaded to match the threads of shaft 310. Alternatively, pilot bit attachment/ejection rod guide collar 330 and hole saw 120 can be separate from each other and be separately threaded onto threaded shaft 310, starting with pilot bit attachment/ejection rod guide collar 330 that can be threaded onto threaded shaft 310, followed by threading hole saw 120 onto threaded shaft 310 until base 125 of hole saw 120 contacts, or nearly contacts, upper surface 331 of pilot bit attachment/ejection rod guide collar 330. In this embodiment, hole saw 120 can, additionally, be held in alignment with pilot bit attachment/ejection rod guide collar 330 through the use of an appropriately threaded nut (not shown) which is threaded onto threaded shaft 310 until it is matingly surfaced against inside surface 127 of hole saw 120. In a still further embodiment, pilot bit attachment/ejection rod guide collar 330 can have an inside diameter that is slightly greater than the outside diameter of threaded shaft 310, and pilot bit attachment/ejection rod guide collar 330 can be slipped into place on threaded shaft 310, held in place by, e.g., a set screw, and hole saw 120 can be threaded onto threaded shaft 310 until base 125 makes contact against upper surface 331 of pilot bit attachment/ejection rod guide collar 330. Also alternatively, hole saw 120 can have an inside diameter slightly greater than the outside diameter of the threaded shaft 310 and can be slipped onto threaded shaft 310 and held matingly surfaced against upper surface 331 of pilot bit attachment/ejection rod guide collar 330 using an appropriately threaded nut threaded onto threaded shaft 310 until the threaded nut contacts inside surface 127 of hole saw 120.
Continuing with assembly of mandrel assembly 300, proceeding from chamfered end 162 of threaded shaft 310, spring 320 is placed onto threaded shaft 310. Thereafter, knurled knob 350 having ejection rods 340 affixed thereto, is placed onto threaded shaft 310. Preferably, knurled knob has a substantially centrally located opening with an inner diameter that is slightly greater than the diameter of threaded shaft 310, simplifying placement of knurled knob 350 onto threaded shaft 310 and alignment of ejection rods 340 with channels 360. This action is followed by threading knurled knobs 351 and 352 onto threaded shaft 310. Threading knurled knobs 351 and 352 onto threaded shaft 310 continues until ends 341 of ejection rods 340 are flush or substantially flush with inside surface 127 of hole saw 120. When knurled knobs 351 and 352 are threaded onto threaded shaft 310 such that ends 341 of ejection rods 340 are flush or substantially flush with inside surface 127 of hole saw 120, knurled knob 352 is fixed in place by use of, e.g., a set screw.
In
Also, in the embodiments shown in
Although the preferred embodiments of the mandrel assembly 300 of the present disclosure utilize pilot bit attachment/ejection rod guide collar 330, pilot bit attachment/ejection rod guide collar 330 can have an alternative construction, or be absent altogether. One such alternative embodiment for pilot bit attachment/ejection rod guide collar 330 is depicted in
Referring to
As mentioned, pilot bit attachment/ejection rod guide collar 330 or 700 can be omitted, with ejection rods 340 proceeding directly from knurled knob 350 through openings 380 disposed in base 125 of hole saw 120. This configuration, however, is not preferred because of the tendency of ejection rods 342 to possibly become misaligned with openings 380 in hole saw 120, or to bend when in use. Also, in either of the embodiments of pilot bit attachment/ejection rod guide collar 330 or 700, ends 341 of ejection rods 340 can be disposed outside of interior space of hole saw 120 and away from opening 360 because the configuration of pilot bit attachment/ejection rod guide collar 330 and 700 provide alignment for end 341 of ejection rod 340 to correctly enter interior space.
Also, knurled knobs 351 and 352 are not required for the practice of the mandrel assembly 300 of the present disclosure, but are preferred. Knurled knob 351 is preferred so that the operator has a larger surface area to grip when drill is reversed. However, knurled knobs 350 and 351 can be combined into a single knurled knob. Likewise, knurled knob 352 can be omitted, although this is not preferred. If knurled knob 352 is omitted, this will necessitate the operator to visually observe the progress of ejection rods 340 out of space 123 to ensure that ends 341 of ejection rods 340 remaining flush or substantially flush with inside surface 126 of hole saw 120. Similarly, although in
In the above detailed description, the specific embodiments of this disclosure have been described in connection with its preferred embodiments. However, to the extent that the above description is specific to a particular embodiment or a particular use of this disclosure, this is intended to be illustrative only and merely provides a concise description of the exemplary embodiments. Accordingly, the disclosure is not limited to the specific embodiments described above, but rather, the disclosure includes all alternatives, modifications, and equivalents falling within the true scope of the appended claims. Various modifications and variations of this disclosure will be obvious to a worker skilled in the art and it is to be understood that such modifications and variations are to be included within the purview of this application and the spirit and scope of the claims.
All of the patents and publications referred to herein are incorporated herein by reference as if fully set forth herein.
This application is related, and claims priority, to U.S. Provisional Application No. 62/117,886 filed on Feb. 18, 2015, that is incorporated herein in its entirety by reference thereto.
Number | Date | Country | |
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62117886 | Feb 2015 | US |