Clamping device for a workbench

Work holders – Relatively movable jaws – With means to align coacting jaw faces

Reexamination Certificate

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Details

C269S153000, C269S155000

Reexamination Certificate

active

06416046

ABSTRACT:

This invention relates to clamping workbenches such as those of the type sold under the Trade Mark WORKMATE and in particular to a secondary clamp for attachment thereto.
BACKGROUND OF THE INVENTION
The “Workmate” and similar portable and collapsible clamping workbenches are now well known. Briefly, they comprise two elongate jaws supported on folding legs, interconnected by threaded rods extending transversely to the longer dimension of the jaws and rotatable by handles to enable the jaws to be relatively moved, towards or away from one another. When closed, the two jaws constitute a workbench, but by opening the jaws a workpiece can be clamped therebetween, for example for sawing or planing or otherwise working on the workpiece. Where an item is too big to be clamped directly between the jaws, it is possible to accommodate the item to be worked on by inserting pegs into the jaws, and to clamp the item between the pegs. A series of apertures have therefore been provided in the two jaws to accommodate pegs at differing distances from the inboard edges of the two jaws.
However, even if the outermost apertures in the boards are used to receive the pegs, the jaws cannot be moved apart sufficiently to enable wide sheet material to be gripped between the pegs. Typically, standard 48″ wide sheets of timber or laminate exceed the workpiece width which is capable of being worked upon by laying it across the workbench between pegs.
It is an object of the present invention to allow a clamping workbench to clamp an item whose width is too great to be clamped in the conventional manner by the jaws, even when fitted with the pegs.
THE INVENTION
According to a first aspect of the invention, in or for a clamping workbench comprising a main pair of jaws carried by a support, and workbench drive means for moving the main jaws towards or away from one another, a supplementary clamping jaw means is provided, adapted to be operatively joined to the main pair of jaws so as to be movable in a direction transverse to the direction of relative movement of the main jaws when the latter are relatively moved by the workbench drive means.
Typically the supplementary jaw is adapted to extend across at least in part both of the two main jaws.
It may extend perpendicularly to the main jaws or at an acute angle thereto.
In one arrangement the supplementary jaw is securable to the main jaws through a linkage which transmits the motion of the main jaws into a direction perpendicular to that motion, to produce the desired movement of the said supplementary jaw.
A second supplementary jaw may be provided, adapted to be fitted to the workbench so as similarly to extend transversely of the main jaws, but spaced from the first supplementary jaw, to allow a workpiece to be clamped between the two supplementary jaws in response to operation of the workbench drive means.
The second supplementary jaw may be adapted to be fixed to one of the two main jaws and be slidable relative to the other so as to permit the full relative movement of the two main jaws.
Alternatively where the workbench provides drive means at both ends of the main jaws for moving them together and apart, the second supplementary jaw may be adapted to be pivotally joined to both of the two main jaws at one end of the workbench whilst the first supplementary jaw is attached to the main jaws near the other end of the workbench, and when both supplementary jaws are so positioned, relative movement between the two supplementary jaws is achieved by operating the workbench drive means at the said other end of the workbench so as to increase or decrease the separation between the two main jaws at that said other end of the workbench only.
Each supplementary jaw may include a retaining lug for engaging the underside of a main jaw to prevent the supplementary jaw from lifting off the main jaws.
Each retaining lug may comprise an L-shaped bracket designed to accommodate the thickness of a main jaw between it and the underside of the supplementary jaw, or may comprise a member mounted at a distance below the supplementary jaw so as to extend below one or both of the main jaws.
To facilitate the fitting of a supplementary jaw when fitted with a retaining member, which is adapted to extend below both main jaws, the member may be movable relative to the underside of the supplementary jaw as by sliding or pivoting to assist in positioning the supplementary jaw or the main jaws.
Typically the supplementary jaw or jaws is/are located above the main jaws.
When fitted to a clamping workbench as aforesaid and mounted transversely to the main jaws thereof at a position spaced from stop means carried by the main jaws, operation of the workbench drive means in one sense will increase the distance between the supplementary jaw and the stop means (for example to allow a workpiece to be laid flat on the main jaws between the supplementary jaw and the stop means) and when operated in the opposite sense will decrease the distance between the supplementary jaw and the stop means to cause the workpiece to be gripped between the stop means and the supplementary jaw.
Conventionally the main jaws include openings into which pegs will fit, and the stop means may comprise one or more such pegs having enlarged heads to prevent them from passing completely through the openings, or the stop means may comprise a second supplementary jaw as aforesaid.
Conveniently the linkage members for mounting the supplementary jaw or jaws to the main jaws may include pegs adapted to be fitted into the stop peg openings in the main jaws.
Alternatively the end of each linkage members may be cut away to define an opening into which the enlarged head of a conventional peg can be received, the latter serving as an end stop for the linkage member.
One preferred arrangement comprises a supplementary jaw having an elongate slot in one longer edge thereof for receiving an end of a linkage arm which is secured therein for sliding and pivoting movement relative to the supplementary jaw, the other end of the linkage arm includes a peg adapted to be a push fit in an opening in one of the main workbench jaws, and the supplementary jaw includes a retention device in the form of an L-shaped bracket, one limb of which is spaced from its underside and defines therewith a channel which is adapted to engage the inner facing edge of the other of the main workbench jaws.
The spacing between the underside of a supplementary jaw and the retention device lug may be adjustable to accommodate different thicknesses of workbench jaw.
The invention finds application in particular to collapsible clamping workbenches sold under the Trade Mark “WORKMATE”. Thus according to a further aspect of the invention, there is provided a secondary clamp for attachment to a collapsible clamping workbench sold under the Trade Mark WORKMATE, comprising a supplementary jaw and means for operatively connecting the supplementary jaw to the workbench jaws, whereby when an operating handle for moving one workbench jaw relative to the other is rotated, relative movement is effected between the said supplementary jaw and the main workbench jaws in a direction transverse to the direction of relative movement of the main workbench jaws, to enable a workpiece laid on the main workbench jaws between the supplementary jaw and stop means attached to one or both of the workbench jaws, to be clamped therebetween.
The stop means may comprise conventional “WORKMATE” pegs fitted into openings in the main workbench jaws or an elongate stop means extending transversely of the two main workbench jaws remote from the placement of the supplementary jaw.
The said elongate stop member may be formed from a single elongate strut adapted to be fitted to the main workbench jaws or may include two shorter elongate struts, one attached to one workbench and the other attached to the other workbench jaw and aligned as required.
In one embodiment the linkage comprises a pair of levers, one for attachment to each of the workbench jaws, each lever having at one end a cylindric

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