Work holders – Relatively movable jaws – Jaw features
Reexamination Certificate
1999-09-24
2001-06-12
Watson, Robert C. (Department: 3723)
Work holders
Relatively movable jaws
Jaw features
C269S219000, C269S221000
Reexamination Certificate
active
06244582
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
In general, the present invention relates to clamps of the type that are commonly used by carpenters to bias pieces of wood together. More particularly, the present invention relates to auxiliary devices that attach to traditional clamps to expand the versatility of the such clamps.
2. Description of the Prior Art
Carpenters, builders, cabinet makers and other professionals that build items from wood often use clamps to temporarily hold pieces of wood together. Often objects made of wood require different pieces of wood to be glued together. Clamps are commonly used to bias glued pieces of wood together as the glue cures.
The prior art is replete with a variety of different clamps that are designed for specific purposes. It is impractical for a carpenter to have a large collection of specialty clamps available, being that the specialty clamps are rarely needed. Rather, many carpenters commonly have a collection of general purpose clamps that they adapt to different needs. One of the most common types of general purpose clamps used by carpenters is the hand screw clamp. Hand screw clamps are also commonly known as dual screw clamps and carpenters clamps.
Referring to
FIG. 1
, a traditional hand screw clamp
10
is shown. The hand screw clamp
10
contains two threaded shafts
12
that pass in parallel through two wooden jaw elements
14
,
16
. Each of the threaded shafts
12
terminate at one end with a handle
18
. Each of the threaded shafts
12
engages the wooden jaw that is farthest away from the handle
18
of that threaded shaft
12
. By selectively turning the threaded shafts
12
, the two wooded jaws
14
,
16
can be biased toward each other at a variety of different angles.
A problem associated with hand screw clamps and similarly constructed clamps, is that the threaded shafts pass between the two wooden jaws. Accordingly, a work piece can only be placed in between the wooden jaws in the areas not obstructed by the threaded shafts. This provides traditional hand screw clamps with an effective clamping range of only a few inches. Accordingly, traditional hand screw clamps are not commonly used to clamp large objects that require a clamping force to be applied several inches from the edge of that object.
In the prior art, there have been auxiliary devices invented that are intended to improve the range and versatility of different types of clamps. One such auxiliary device for a hand screw clamp is shown in U.S. Pat. No. 5,335,898 to Johnson, entitled Apparatus And Method For Clamping Structural Members During Joinder. Such a device does enable a hand screw clamp to clamp together objects otherwise not capable of being clamped by a hand screw clamp. However, to utilize the auxiliary extension, dowel holes must be drilled in the wood being clamped. Accordingly, such auxiliary attachments only have limited applications.
A need therefore exists for an auxiliary device that can be added to a clamp that significantly increases the range and versatility of the clamp without having to modify the wood being clamped. This need is met by the present invention as is described and claimed below.
SUMMARY OF THE INVENTION
The present invention is a system and associated method of use for an extension device that attaches to hand screw clamps and similarly configured clamps. Hand screw clamps have two jaw elements that are interconnected by two threaded shafts. As the threaded shafts are turned, the jaw elements can be biased toward each other in a variety of configurations. The system includes a first tubular element having an open end. Two opposing slots are present on the first tubular element that extend inwardly a predetermined distance from the open end. The open end of the first tubular element is sized to receive a first of the jaw elements of the hand screw clamp, wherein the threaded shafts of the hand screw clamp pass into the slots.
The system also includes a second tubular element having an open end and two opposing slots that extend inwardly a predetermined distance from that open end. The open end of the second tubular element is sized to receive a second of the jaw elements therein. The first and second tubular extension elements extend beyond the length of the jaw elements of the hand screw clamp. The first and second tubular extension elements can also have different configurations, thereby altering the configuration of the clamp. The present invention therefore enables a single clamp to be configured into multiple different lengths and configurations.
REFERENCES:
patent: D. 264300 (1982-05-01), Imm
patent: 1781997 (1930-11-01), Berezowski
patent: 2671366 (1954-03-01), Beusch
patent: 3499206 (1970-03-01), Quernheim
patent: 3767183 (1973-10-01), Van Gelder
patent: 4265436 (1981-05-01), Wagster
patent: 4580769 (1986-04-01), Pappas
patent: 5335898 (1994-08-01), Johnson
patent: 5697268 (1997-12-01), Makovsky et al.
patent: 5921536 (1999-07-01), Bernstein
patent: 5996447 (1999-12-01), Baymouth
LaMorte & Associates
Watson Robert C.
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