Tools – Wrench – screwdriver – or driver therefor – Stud-removal and implacement
Reexamination Certificate
2003-05-12
2004-06-01
Hail, III, Joseph J. (Department: 3723)
Tools
Wrench, screwdriver, or driver therefor
Stud-removal and implacement
C007S158000
Reexamination Certificate
active
06742416
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a bit for removing damaged screws by backing them out. More specifically, this invention relates to such a bit especially adapted for use in a power drill running in a counter-clockwise direction.
BACKGROUND OF THE INVENTION
In U.S. Pat. Nos. 4,406,917, 4,777,850, 5,031,487, and 5,251,516 assigned to my assignee, there are disclosed various bits and other devices for removing broken bolts. U.S. Pat. No. 5,251,516, for instance, involves chucking a bit in a power drill and running the drill clockwise and making a small hole in the broken end of the bolt. A reverse threaded device is then snugly inserted in the drill chuck, the rotation of the drill reversed, and the bit is moved into the hole. The threads on the reverse threaded device catch the edges of the hole and spin the broken bolt out of the hole.
There has been a need for a device to remove screws, the heads of which have been damaged by rounding out the Philips screw cross recess or ripping out the side of the slot of a regular screw. Also, the screw head may have been covered by paint so that the recess or slot is no longer pronounced enough to get a good purchase on it by a screwdriver.
SUMMARY OF THE INVENTION
For removing damaged screws, the invention is a bit having an axis and a tip end. The tip end has diametrically opposed scraping surfaces with edges, the surfaces facing in a counter-clockwise direction. The surface and edges are in the plane of the axis. Behind each scraping edge is a support area. The support area may have its face relieved so as to make the scraping edge more pronounced. The edges meet in a point at an obtuse angle.
REFERENCES:
patent: 4713990 (1987-12-01), Poling
patent: 4777850 (1988-10-01), Polonsky
patent: 5031487 (1991-07-01), Polonsky
patent: 5251516 (1993-10-01), Desaulniers
Alden Corporation
Hail III Joseph J.
Hoopes Dallett
Thomas David B.
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