Cutting by use of rotating axially moving tool – With work-engaging structure other than tool or tool-support – Frictionally engaging sides of opening in work
Reexamination Certificate
2000-10-16
2002-06-25
Howell, Daniel W. (Department: 3722)
Cutting by use of rotating axially moving tool
With work-engaging structure other than tool or tool-support
Frictionally engaging sides of opening in work
C408S201000, C408S204000
Reexamination Certificate
active
06409437
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
No known prior filed copending nonprovisional applications.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
No federally sponsored research or development involved.
REFERENCE TO A MICROFICHE APPENDIX
Not appicable.
BACKGROUND OF THE INVENTION
A hole saw is a well known cylindrical saw with teeth on the forward edge to cut large diameter holes in various solid materials. They all use a pilot bit centered in the middle to anchor the hole saw as it begins cutting. An arbor is used to attach the hole saw to a portable electric drill for power.
When a hole larger than the pilot bit exists where the new hole is to be drilled, hole saws have a serious drawback. Without the pilot bit anchored in the material to be cut, the hole saw at best wanders about the surface marring it, and not drilling where desired. At worst, with wood and large diameter saws, it will catch on one edge and violently spin off the surface.
Various devices have been developed in the past to solve the above problems and enlarge a prexisting hole.
The hole saw centering device solves the problems with less complication and more versatility than the others.
In U.S. Pat. No. 3,630,632 to Holleman, U.S. Pat. No. 5,069,584 to Obermeier, and U.S. Pat. No. 5,074,722 to Cochran devices are disclosed that use various means other than a hole saw to enlarge the hole, making such devices much more complicated and costly.
In U.S. Pat. No. 5,743,682 to Chaney a cone is used to locate a larger hole saw, but it employs complicated means to offset the hole, is restricted in the size existing hole it may enlarge, and was designed specifically for door knobs as stated.
In U.S. Pat. No. 5,413,437 to Bristow a second arbor is used to locate a hole saw the same diameter as the existing hole, restricting the device to enlarging standard size holes and requiring the possession of the correct size hole saw for a guide.
In U.S. Pat. No. 5,820,315 to Collard, U.S. Pat. No. 5,366,326 to Converse, and U.S. Pat. No. 4,579,486 to Damico devices are disclosed that use cylinders to locate the larger hole saw on the existing hole. They require mechanical attachment to the larger hole saw, and or adjustment for size, and are restricted in the size hole they may locate.
BRIEF SUMMARY OF THE INVENTION
The hole saw centering device is an invention to locate a hole saw in a place where a hole larger than the pilot bit exists.
It consists of a cone to center the hole saw, a spring to tension the cone against the work piece, and a hardened steel insert threaded in the cone to locate the pilot bit in the cone without damaging it if the pilot bit is used. It also features a shoulder on the cone to locate the cone in the hole saw if the user wishes not to use the pilot bit for fear of damaging items installed behind the hole.
It will accomplish the above with no mechanical attachment or adjustment on any size hole from the interior diameter of the hole saw to the exterior diameter of the pilot bit.
REFERENCES:
patent: 4203692 (1980-05-01), Jensen
patent: 5366326 (1994-11-01), Converse
patent: 5743682 (1998-04-01), Chaney, Sr.
patent: 5904454 (1999-05-01), Washer
patent: 6305885 (2001-10-01), Linthicum
patent: 61-152309 (1986-07-01), None
Howell Daniel W.
Yeager Arthur G.
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