Workpiece positioning adapter for pliers such as toggle clamps

An adapter plate for removable attachment to a U-shaped lower jaw of a set of toggle clamps is disclosed. The adapter plate is constructed of a rigid metal suitable for providing a backing for a joint to be welded by means of a MIG welding or arc welding process such as copper or brass. The plate is triangularly shaped and includes upper and lower broad flat surfaces, a base side and a pair of adjacent sides extending from opposite ends of the base side and intersecting at a predetermined angle to form an apex. The plate contains beveled edges for clearing the rounded inside cornters of a pair of angle iron workpieces when said workpieces are placed against one or more sides of the plate to be positioned relative to one another for being held by the clamps for welding the workpieces together or for other purposes. The plate can be used to position the workpieces in the clamps against the adjacent sides at the predetermined angle relative to one another, such as a right angle, or it can be used to position the workpieces against the base side in a straight end-to-end alignment relative to one another. A weld joint backing walls for attachment to the plate for welding two angle irons together are also disclosed.

BACKGROUND OF THE INVENTION 
This invention relates generally to an adapter plate for mounting in a pair 
of pliers for precisely positioning a pair of workpieces relative to one 
another to be held by the pliers for welding the workpieces together 
and/or for other purposes. More specifically, this invention relates to a 
triangularly shaped adapter plate for removable mounting in a set of 
pliers or clamps for precisely positioning a pair of workpieces in the 
pliers or clamps relative to one another in either of two different 
alignments. 
Welders often use a conventional set of pliers of the type shown as toggle 
clamps to firmly hold two metal workpieces in fixed positions relative to 
one another for welding the workpieces together in a desired alignment. It 
is often necessary to use such clamps to hold two angle iron members or 
flat bars at right angles relative to one another for welding a properly 
prepared miter joint between them to form an L-shaped assembly or one 
corner of a rectangular frame. In the case of a closed rectangular frame, 
four flat bars or angle irons will be arranged in a rectangle with 
opposing ends properly mitered, after which opposing corner portions of 
the frame members will be securely gripped and held in a right angle 
alignment using four of such clamps. The mitered joints are then welded 
together while the adjacent workpieces are held with clamps. However, it 
is very difficult to obtain and secure a precise right angle alignment 
between adjacent members of a frame. Failure to obtain four precise right 
angle corners in a rectangular frame upon welding of the corner joints can 
result in deformations and stresses in the frame. 
I have performed a preliminary patent search and have not found nor am I 
otherwise aware of any prior art adapter for use in pliers, such as toggle 
clamps, which will serve to guide the precise positioning of two 
workpieces in the clamps so that they can be firmly held at a precise 
right angle, or any other angle for that matter, relative to one another 
for being welded together or for other purposes. By means of my invention, 
I provide such an adapter which can also be used to align two workpieces 
in a precise straight end-to-end alignment for welding the two workpieces 
together. My invention thus substantially overcomes these and other 
difficulties encountered in the prior art when precisely arranging and 
positioning metal workpieces relative to one another in a set of 
conventional pliers or clamps. 
SUMMARY OF THE INVENTION 
It is an object of my invention to provide a workpiece positioning adapter 
plate for attachment to a jaw of a set of pliers or clamps to permit the 
precise positioning of a pair of workpieces in the set for being held by 
the set at precise positions relative to one another for welding the 
workpieces together or for performing other operations on the workpieces. 
It is a further object of my invention to provide such a workpiece 
positioning adapter which has the capability of positioning two workpieces 
in a set of clamps at either a predetermined angle relative to one another 
or in straight end-to-end alignment relative to one another as desired. 
It is also an object of my invention to provide a workpiece positioning 
adapter for attachment to a set of pliers or clamps which also provides a 
suitable backing for a joint to be welded between two workpieces held in 
the set using either a MIG welding process or an arc welding process. 
It is yet another object of my invention to provide a workpiece positioning 
adapter for attachment to a set of pliers or clamps which is capable of 
precisely positioning a pair of angle iron workpieces in the set. 
Briefly, in accordance with my invention, there is provided a workpiece 
positioning adapter for a set of clamps of the type used for holding a 
pair of metal workpieces for welding the workpieces together. The adapter 
comprises a rigid triangularly shaped plate. The plate includes upper and 
lower broad flat surfaces, a base side and a pair of adjacent sides. The 
adjacent sides extend from opposite ends of the base side and intersect 
with one another at a predetermined angle to form an apex. The adapter 
also comprises a first means for mounting the plate between the jaws of a 
set of clamps of the type used for releasably gripping a pair of 
workpieces such that the workpieces can be positioned along the adjacent 
sides and held by the clamps at the predetermined angle relative to one 
another.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to the drawing figures there is shown, in a preferred 
embodiment of my invention, a novel workpiece positioning adapter plate 
generally designated 10, for use with a conventional set of welder's 
pliers of the type known as toggle clamps, generally designated 12. 
The toggle clamps 12 includes a U-shaped lower jaw 14 having a pair of 
parallel, spaced apart arms 16a and 16b which essentially lie in a single 
plane. See particularly FIGS. 4-5 and 9. The clamps 12 also includes an 
upper jaw 18 having a U-shaped portion which generally conforms in size 
and shape to the lower jaw 14. A pair of gripping fingers 20a and 20b 
extend perpendicularly from the ends of the arms of the U-shaped portion 
toward end portions of the arms 16a and 16b, respectively, of the lower 
jaw 14. The base of the U-shaped portion of the upper jaw 18 is fixedly 
connected to an upper handle 22. The base of the lower jaw 14 is fixedly 
connected to a rocker element 23 which is, in turn, pivotally connected to 
both the upper arm 22 and a lower arm 24. Accordingly, the lower jaw 14 is 
pivotally movable relative to the fingers 20a and 20b of the upper jaw 18 
between an open and a closed position with movement of the lower handle 24 
relative to the upper handle 22. The position of the lower handle 24 can 
be locked relative to the upper handle 22 by means of a lever 25 to lock a 
workpiece between the lower jaw 14 and the fingers 20a and 20b of the 
upper jaw 18. An adjustment screw 26 permits locking of the lower jaw 14 
relative to the fingers 20a and 20b at various spaced apart positions to 
permit locking of the clamps 12 to workpieces of different thicknesses. 
The plate 10 may also be used as a backing for a joint to be welded between 
two workpieces, such as a pair of angle iron members 28 and 30 held in the 
clamps 12 when using either a MIG welding process, an are welding process 
or any other type of welding process wherein the weld material will not 
stick to brass or copper. The plate 10 comprises a relatively flat 
triangularly shaped part constructed of either copper, brass or other 
metal or metal alloy to which weld material will not stick during a MIG or 
are welding operation. In the present example, the plate 10 is constructed 
in the shape of a right triangle such that it has two relatively broad, 
flat surfaces, and three relatively thin sides, including a base side 32 
and two equal length adjacent sides 34 and 36, which adjacent sides meet 
to form an apex 38 at an angle of 90 degrees. 
The plate 10 of the present example can therefore be used to position the 
two members 28 and 30 in the jaws 14 and 18 of the set 12 at either a 
right angle relative to one another or in a straight end-to-end alignment, 
depending upon how the plate 10 is mounted in the clamps 12. In order to 
use the plate 10 in both of these alignment modes it is necessary that it 
be removably attachable to the lower jaw 14. To accomplish this, a slight 
modification of the lower jaw 14 may be necessary. In the present case, I 
weld or otherwise attach a flat steel bar 40 between end portions of the 
arms 16a and 16b. See FIGS. 4-5 and 9. Inwardly of both ends of the bar 
40, a pair of machine screw holes 42 is drilled and tapped therethrough. 
In registry with these tapped holes 42 in the bar 40, a pair of enlarged 
untapped holes 44 is drilled through the arms 16a and 16b. 
For the arrangement of the plate 10 as shown in FIGS. 1 and 3-5, a first 
pair of enlarged untapped holes 46 is drilled through the plate 10 near 
the base side 32 which are spaced apart along the base so as to register 
with the tapped holes 42 of the bar 40 and the enlarged untapped holes 44 
of the arms 16a and 16b. See also FIG. 2. The holes 46 are countersunk as 
at 48 where they open onto an upper broad surface 50 of the plate 10. The 
plate 10 is then mounted on the jaw 14 and secured thereto with suitable 
threaded fasteners 51 which are inserted head up, first, into and through 
the countersunk openings 48 of the holes 46, thence threaded through the 
tapped holes 42 of the bar 40 and, finally inserted into the untapped 
holes 44 in the legs 16a and 16b. Since the material from which the plate 
10 is made is a relatively soft brass or copper, the defining surfaces of 
the holes 46 are not suitable for being threaded to secure the fasteners 
51 thereto as such threading would not be durable. Moreover, since the 
arms 16a and 16b will usually be made of a case hardened steel, the 
defining surfaces of the holes 44 formed therethrough would be extremely 
difficult to tap for securing the screws 51 therein. Therefore, the bar 40 
should be made of a suitable soft steel wherein the defining surfaces of 
the holes 42 can be readily tapped to provide durable threads for securing 
the screws 51 therein. 
For the arrangement of the plate 10 as shown in FIGS. 7-9, a second pair of 
enlarged untapped holes 52, which are equally spaced apart relative to the 
holes 46 and which are located near the adjacent sides 34 and 36, are 
drilled through the plate 10 so as to be registrable with the holes 42 and 
44. The holes 52 are then countersunk as at 54 where they open onto a 
lower broad surface 56 of the plate 10. As shown best in FIG. 9, the plate 
10 is then mounted on the jaw 14 with the broad side 56 up and secured 
thereto with the threaded fasteners 51 which are inserted head up, first, 
through the countersunk untapped holes 52, thence threaded through the 
tapped holes 42 of the bar 40 and, finally, are inserted into the untapped 
holes 44 of the legs 16a and 16b. 
Where the angle iron members 28 and 30 are formed from soft steel plate by 
bending the sides thereof until they are perpendicular to one another, as 
is usually the case, the resulting elongated inside corners of the members 
28 and 30 will be slightly rounded on a small but definite radius. Such 
rounded corners can interfere with the precise alignment of the flat sides 
of the members 28 and 30 along and against the sides 32, 34 and 36 of the 
plate 10. To avoid this possibility, I prefer to bevel the elongated edges 
of the plate 10 between the broad surfaces 50 and 56, on the one hand, and 
the flat sides 32, 34 and 36 on the other hand, in order for the edges to 
clear the rounded corners of the members 28 and 30 when one or more of 
those sides is placed flush against one or more of the sides of the plate 
10. The beveled edges of the plate 10 are shown in various drawing figures 
at 58. 
In the plate and clamps arrangement shown in FIGS. 1 and 3-5, the plate 10 
is mounted on the jaw 14 with the apex 38 projecting forwardly of the jaws 
14 and 18 and pointing away from the handles 22 and 24. This arrangement 
is used to position the members 28 and 30 precisely perpendicular to one 
another along and against the adjacent sides 34 and 36, respectively, so 
that the clamps 12 can secure the members in that position for welding 
them together along a first side seam 60a of a miter joint. While the 
first side seam 60a is being welded, the broad surface 50 forms a backing 
to restrain the weld material from leaking out of the seam while molten 
and before the weld material has solidified. In some cases, in order to 
properly finish welding the joint, a second side seam 60b must also be 
welded, which must also be fully backed so as to prevent molten weld 
material from leaking therethrough. 
To accomplish this, a pair of weld joint backing bars 62 and 63 are 
provided, as shown best in FIG. 6, which are removably attached to the 
plate 10 as shown in FIGS. 1 and 3-5. Specifically, the bars 62 and 63 are 
arranged so as to attach to the underside 56 of the plate 10 and extend 
along the adjacent sides 34 and 36, respectively, Each of the bars 62 and 
63 contain a single upwardly opening slot 64a and 64b, respectively, into 
which distal ends of the arms 16a and 16b project as best shown in FIG. 4. 
Blind tapped holes 65 are formed in the plate 10 so as to open onto the 
underside surface 56 in registry with untapped holes 66 formed through the 
bars 62 and 63. A pair of suitable threaded fasteners 67 are inserted 
upwardly through the holes 66 and threadably inserted into the blind holes 
65 to secure the bars 62 and 63 to the plate 10. A base portion of the 
holes 66 may be countersunk to accommodate the heads of the fasteners 67 
as shown in FIG. 5. In this manner, the bars 62 and 63 can be used to 
provide a suitable backing for welding the seam 60b. It will be 
appreciated that the height of the bars 62 and 63 should be such that a 
backing is provided for the entire length of the seam 60b to be welded. It 
is also important that the outwardly facing vertical sides of the bars 62 
and 63 be closely aligned with the vertical sides 34 and 36 of the plate 
10 so that the angle irons 28 and 30 rest flush against both surfaces when 
arranged as shown in FIG. 1. 
The plate 10 can also be used to position a pair of flat workpiece bars 
having properly mitered opposing ends at a right angle within the clamps 
12 for welding the flat bars together or for other purposes. In such a 
case, outwardly facing edges of such flat bars should be manually aligned 
by sight with the adjacent sides 34 and 36 of the plate 10 prior to 
clamping the flat bars against the plate 10 between the jaws 14 and 18. 
With proper care, an accurate right angle weld joint can thus be obtained 
between two such flat bars. The backing bars 62 and 63 need not be 
attached to the plate 10 when securing and welding such flat bars 
together. 
For the arrangement of the members 28 and 30 as shown in FIGS. 7-9, the 
plate 10 is mounted on the jaw 14 with the apex 38 located between the 
arms 16a and 16b near the base of the jaw 14 and pointing toward the 
handles 22 and 24. This arrangement is used to position the members 28 and 
30 in a precise end-to-end alignment with opposing ends forming a suitable 
butt joint as at 70a and 70b in FIG. 8. The members 28 and 30 are aligned 
along the base side 32 of the plate 10 with the jaws 14 and 18 open. When 
the proper alignment spacing for the joint 70a and 70b is obtained, the 
jaws 14 and 18 are closed to tightly secure the members 28 and 30 in 
position and the side seam 70a is welded using the surface 56 as a backing 
for the weld. To weld the side seam 70b, the jaws 14 and 18 are opened and 
the members 28 and 30, now welded together along the seam 70a, are turned 
180 degrees horizontally as viewed in FIGS. 8-9 and rotated through a 
vertical arc counterclockwise, as viewed, about an axis concurrent with 
their longitudinally extending inside corners. The members 28 and 30 are 
then placed back against the side 32 so that the seam 70b lies upon the 
plate surface 56. The jaws 14 and 18 are then closed a second time to hold 
the members 28 and 30 while the side seam 70b is welded. 
In the alternative and to avoid having to interrupt the welding process 
between the welding of the seams 70a and 70b to loosen the jaws 14 and 18 
so that the members 28 and 30 can be turned around and over for 
reinsertion into the clamps 12, an elongated weld joint backing bar 72 as 
shown best in FIG. 10 is connected to the underside 50 of the plate 10 as 
shown in FIGS. 7-9. The bar 72 is conveniently fastened to the broad 
surface 50 so as to depend downwardly therefrom as viewed. Like the 
backing bars 62 and 63, as previously explained, the backing bar 72 should 
be constructed of a metal suitable for forming a backing for a MIG or arc 
welded joint such as brass or copper. Its length is not particularly 
important just so long as it extends fully across the joint 70b to be 
welded and so long as it can be fastened to the plate 10 on both sides of 
the weld joint 70b with suitable spacing therefrom. The bar 72 contains a 
pair of spaced apart upwardly opening slots 73 in which distal ends of the 
arms 16a and 16b may project when the bar 72 is fastened to the plate 10 
along the base side 32. The forwardly facing vertical surface of the bar 
72 should be precisely aligned with the vertical face of the side 32 when 
the bar is fastened to the plate 10. The height of the backing bar 72 
should be such as to form a backing for the seam 70b along its entire 
length. In the present example, the bar 72 is approximately the same 
length as the plate side 32, as best seen in FIG. 7. A pair of spaced 
apart and untapped holes 74 is drilled through the bar 72 from top to 
bottom so as to register with a pair of tapped blind holes 76 drilled in 
the plate 10 which open on the broad surface 50. Base portions of the 
holes 74 are countersunk to accommodate the heads of suitable threaded 
fasteners 78 which extend upwardly as viewed through the untapped holes 74 
in the backing bar 72 and are received and retained in the tapped blind 
holes 76 of the plate 10. 
In actual practice, I have employed a VISE-GRIP brand set of toggle clamps 
as the clamps 12 of the present example. The plate 10 used with it is made 
of brass and has a base side length of 5.25 inches and the adjacent sides 
are both 3.75 inches in length. The holes 46 are 1.69 inches from the ends 
of the base side 32 as measured along the base side 32 and are 0.37 inches 
in from the base side as measured perpendicular thereto. The holes 46 are 
spaced apart 1.88 inches center to center. The holes 52 near the adjacent 
sides 34 and 36 are, likewise, 1.88 inches apart, center to center, and 
are spaced perpendicularly inward from the base side 32 a distance of 1.25 
inches. The holes 46 and 52 are large enough in diameter to confine 6-32 
screws. The thickness of the plate 10 is 1/4 inch. The top and bottom 
edges of the plate 10 are beveled on approximately a 45 degree angle and 
have a height along the sides of the plate of approximately 0.12 inches. 
Using a plate 10 of these dimensions, I found it necessary to grind a 45 
degree bevel 80 (FIG. 4 only) on the outer corners of the arms 16a and 16b 
of the Vise-Grip lower jaw 14 in order for the adjacent sides 34 and 36 to 
clear the arms when the plate 10 of the foregoing dimensions was mounted 
as shown in FIGS. 1 and 3-5. 
It will be appreciated that the angle of the apex 38 is not limited to 
being a right angle. The apex angle at 38 can be of any other reasonable 
angle, either above or below 90 degrees, as needed for aligning members 
such as at 28 and 30 at such other angle. Apex angles less than 90 degrees 
might be limited in part by the size and shape of the particular set of 
clamps being used and/or by the amount of bevel grinding required on outer 
corners of the legs 16a and 16b. Also, it will be appreciated that other 
types of clamps and pliers may be usable with the adapter plate of my 
invention apart from the preferred clamps 12 of the present example. 
Certainly, the clamps of pliers employed need necessarily not be of the 
toggle operated type. Further, it will be appreciated that other means of 
fastening of he adapter plate of my invention to a set of clamps or pliers 
is within the scope of my invention. For example, where it is only desired 
to use the plate 10 for positioning workpiece members at right angles 
relative to one another or, for that matter, at some other predetermined 
angle relative to one another, the adapter plate can be permanently welded 
or otherwise permanently affixed to the arms 16a and 16b of the lower jaw 
14 such that the apex 38 points forwardly away from the handles 22 and 24. 
Although the present invention has been explained and illustrated with 
respect to specific details of a certain preferred embodiment thereof, it 
is not intended that such details limit the scope of this patent other 
than as specifically set forth in the following claims.