Auxiliary drop-in table top power tool base

An auxiliary base plate assembly for converting a portable power tool such as a router having an integral base plate and a pair of parallel guide rods affixed to the integral base plate and extending laterally from opposite sides thereof to a stationary bench-type power tool including: a work bench having a first through vertical opening in its top surrounded by an inwardly extending peripheral flange recessed below the top surface of the work bench by a predetermined distance; an auxiliary base plate member having a thickness equal to the predetermined distance and having a centrally located, vertically extending, second through opening and a pair of parallel, horizontal through bores intersecting the second through opening and positioned to receive the ends of the power tool's guide rods wherein the second through opening is shaped to receive and surround the power tool's integral base plate so as to permit mounting of the auxiliary base plate member on the power tool by insertion of the guide rods into the parallel bores and lateral shifting thereof through the power tool's integral base plate whereupon the assembled power tool and the auxiliary base plate member may be inverted and inserted into the first through opening in the work bench top for support by the inwardly extending flange; with the work bench top, and the inwardly facing surfaces of the auxiliary base plate members and the power tool's integral base plate lying in a common plane defining a work surface.

BACKGROUND OF THE INVENTION 
1. Technical Field 
The present invention relates to power tools; and, more particularly, to an 
auxiliary power tool base assembly for usage with portable power tools, 
such as a router, which employ guides and guide rods wherein the auxiliary 
base assembly can be readily attached to the portable power tools after 
removal of the guide for enabling the router or other tool and the 
auxiliary base assembly to be inverted and dropped into a flanged opening 
in a work table where the opening is complementary to the auxiliary power 
tool base assembly so as to permit usage of a portable power tool as a 
stationary table top tool where the only portion of the tool extending 
above the plane of the work table's top is the cutting implement such as a 
router bit. 
While the present invention finds particularly advantageous use with many 
conventional portable routers since such tools commonly employ guides and 
one or more guide rods, as the ensuing description proceeds those skilled 
in the art will appreciate that other portable power tools such as, merely 
by way of example, jig saws, circular saws and the like, can be readily 
modified by the tool manufacturer to incorporate one or more removable 
guide rods associated with the tool's integral base plate; and, therefore, 
the present invention can also be used in conjunction with such other 
modified portable power tools. That is to say, the invention is not 
limited to use with portable routers. Nevertheless, the invention will 
herein be described in a non-limiting way in conjunction with a portable 
power router. 
2. Background Art 
The prior art is replete with disclosures of a wide variety of power tools 
including routers and varying support mechanisms heretofore used as 
stationary table top support arrangements for portable power tools where 
only the tools' cutting implement extends above the work table top. 
Typical of such disclosures is that found in U.S. Pat. No. 
4,774,986--LaGra wherein the patentee discloses a system more particularly 
shown in FIGS. 1 and 2 for supporting a router beneath the top of a 
stationary work table. In this arrangement the router is secured to an 
adapter plate by means of threaded fasteners passing through the adapter 
plate and into the router base plate. The adapter plate is dimensioned to 
drop into a complementally shaped recess in the work table top. 
In McCambridge et al U.S. Pat. No. 4,350,193 assigned on its face to 
Central Quality Industries, Inc., a power tool accessory table is 
described which is said to enable mounting of a wide range of portable 
power tools including, for example, a router. In this construction, the 
router or other power tool is secured to a separable base plate which is 
then inverted and laid crosswise over an opening formed in a work table 
top where the base plate rests on a peripheral flange integral with the 
table top. The patent is principally directed to the flange arrangement 
for securing the base plate to the table top as contrasted with any 
specific arrangement for securing the base plate to the power tool. 
Murphy U.S. Pat. No. 4,335,765 is of interest for its disclosure of a 
portable multi-purpose construction table. Again, the table is designed to 
accept a wide range of portable power tools including routers which may, 
as shown in FIG. 3, be clamped to the underside of the table top by 
L-shaped clamps. 
Similarly, Nash et al U.S. Pat. No. 4,265,283 assigned on its face to the 
Triangle Corporation, is of interest for its disclosure of elongate 
channel shaped brackets and clamps for securing a router or other portable 
power tool to the underside of a work table. Similar arrangements are also 
disclosed in Stone U.S. Pat. No. 4,186,784, assigned on its face to 
Atlantic Container Corporation, and Groehn U.S. Pat. No. 2,799,305. 
U.S. Pat. No. 2,615,479--Bearup is of incidental interest for its 
disclosure of a router bit mounted on a removable insert which is 
supported in a work table top opening; but, in this instance, the router 
bit is geared to a drive shaft for a table saw. Snow U.S. Pat. No. 
4,312,391 is similarly of incidental interest for its disclosure of an 
adapter permitting mounting of a router on the arm of a radial saw. 
In general, each of the foregoing proposed approaches for mounting portable 
routers on a stationary work table employs clamps, mounting brackets, 
threaded fasteners and similar devices for securing the router in place. 
Consequently, these devices are difficult and time consuming to assemble 
and disassemble. Moreover, they are not particularly stable or safe since 
there is a tendency for the clamps, mounting brackets, threaded fasteners 
and the like to loosen as a result of vibrations inherently set up during 
usage of the tool. 
Cowman U.S. Pat. No. 4,718,468, assigned on its face to Black & Decker, 
Inc., while not related to devices for securing routers to a fixed work 
table top, is nonetheless of general interest for its disclosure of a 
relatively conventional present-day router construction available from a 
number of manufacturers. In this particular instance, the router includes 
a base plate to which are removably secured a pair of parallel guide rods 
which are here used to support a router guide. 
SUMMARY OF THE INVENTION 
The present invention takes advantage of the type of router construction 
disclosed in the aforesaid Cowman U.S. Pat. No. 4,718,468 by employing the 
guide rods to mount the router or other power tool on an auxiliary base 
plate assembly which can then be inverted and dropped into a flanged 
opening in a work bench table top, thereby totally eliminating the need 
for usage of clamps, brackets, threaded fasteners or the like which have a 
tendency to loosen. 
More specifically, it is a general object of the present invention to 
provide an auxiliary router or other power tool base assembly for portable 
routers and the like which enables such portable tools to be supported 
from a work bench table top with only the router bit or other cutting 
implement extending above the plane of the table top, yet which does not 
require any separate mounting brackets, clamps or fasteners and which 
permits of ease of assembly and disassembly and is, at the same time, 
characterized by its economy, rigidity, stability and safety in operation. 
To this end, the auxiliary base plate assembly of the present invention 
comprises a pair of complementary, mating, auxiliary base plate members 
each having at least one linear edge adapted to be oriented in 
edge-to-edge abutting relation with their abutting linear edges cut out to 
form a pair of generally C-shaped complementary auxiliary base members 
designed to fit snugly about the base plate of a conventional router or 
similar power tool. In the illustrative embodiment of the invention, the 
pair of auxiliary base plate members, when abutted together edge-to-edge, 
define a rectangular configuration with a central opening; but, they need 
not define a rectangle provided only that the resulting composite 
auxiliary base plate is non-circular. Each of the pair of complementary, 
mating, auxiliary, base plate members is provided with a pair of parallel 
transverse through bores extending horizontally through the auxiliary base 
plate members in a direction normal to the abutting edges thereof, with 
such bores positioned and dimensioned to receive the free projecting ends 
of the power tool's guide rods when the latter are generally centered with 
respect to the power tool base plate and affixed thereto. 
Thus, the arrangement is such that in assembly the router or other tool may 
be placed, with its integral base plate down, on a flat horizontal surface 
with its two (2) parallel guide rods extending symmetrically from the 
integral base plate in opposite directions. The two (2) mating, auxiliary 
base plate members are then laid on the flat horizontal surface and moved 
towards the power tool's integral base plate and one another, with the 
guide rods being received within respective ones of the parallel 
transverse horizontal bores formed in the two (2) auxiliary base plate 
halves. 
When the two (2) auxiliary base plate members have been shifted into 
edge-to-edge abutting relation with the power tool's integral base plate 
snugly received within the facing C-shaped complementary cutouts in the 
auxiliary base plate members, the entire assembly is inverted and the 
auxiliary base plate assembly defined by the two (2) mating auxiliary base 
plate members is positioned within a complementally shaped through opening 
formed in a work bench table top, such opening having an inwardly 
extending peripheral flange recessed below the work bench table top by a 
depth equal to the thickness of the auxiliary base plate. As a 
consequence, the router or other power tool is supported beneath the work 
bench table top in a rigid, stable, immovable position due to 
inter-engagement between the guide rods and the auxiliary base plate 
halves; and, the work bench table top, the upwardly facing surfaces of the 
auxiliary base plate halves, and the bottom of the power tool's integral 
base plate all lie in a smooth, uninterrupted, continuous common plane. 
The confining edges of the flanged recessed opening in the work bench 
table top serve to prevent movement of the auxiliary base plate halves 
relative to the table top, one another and/or the power tool's integral 
base plate; and, at the same time, the guide rods are retained captive 
within the parallel bores in the auxiliary base plate halves and are 
prevented from movement even under conditions where the means for o 
securing the guide rods to the integral base plate loosen during usage of 
the tool. 
Thus, the arrangement is such that the auxiliary base plate members 
comprise a conversion assembly for quickly and easily converting a 
conventional portable power tool to a stationary bench-top tool wherein 
the tool is integrally, although separably, mounted in a work bench in a 
fixed immovable position relative to the work bench with the tool bit 
extending above the work surface defined by the bench top; yet wherein no 
separate clamps, brackets, screws or other fastening devices are employed 
and the only components required are the power tool with its guide rod(s), 
the auxiliary base plate members, and a work bench. 
It will be understood as the ensuing description proceeds that while it is 
convenient to form the auxiliary base plate of two (2) complemental halves 
adapted to be abutted in edge-to-edge relation, it is within the scope of 
the invention to subdivide the auxiliary base plate into two (2) or more 
pieces which individually comprise more and/or less than one-half of the 
assembled unit. Indeed, the auxiliary base plate could be made of a single 
unitary piece with a central through opening adapted to accommodate a 
given portable power tool's integral base plate provided only that the 
auxiliary base plate is provided with one or more suitable transverse 
through bores which permit of lateral insertion of the tool's guide rod(s) 
through such bore(s) and the aligned guide rod opening(s) in the power 
tool's base plate when the latter is positioned within the through central 
opening in the one piece auxiliary base plate.

While the invention is susceptible of various modifications and alternative 
forms, a specific embodiment thereof has been shown by way of example in 
the drawings and will herein be described in detail. It should be 
understood, however, that it is not intended to limit the invention to the 
particular form disclosed but, on the contrary, the intention is to cover 
all modifications, equivalents and/or alternatives falling within the 
spirit and scope of the invention as expressed in the appended claims. 
DETAILED DESCRIPTION 
Turning now to the drawings, and directing attention first to FIG. 1, there 
has been illustrated a portable power tool which here takes the form of a 
conventional router, generally indicated at 20. As is conventional with 
commercially available portable routers of the type here depicted at 20, 
the router includes a main body 21, an electric plug-in type power cord 
22, a pair of handle elements 24, 25, a drive socket 26, and an integral 
base plate 28, which, in this instance, is secured to the router's main 
body 21 by a pair of parallel, spaced apart, vertical posts 29, 30. Base 
plate 28 is provided with a central opening 31 coaxial with the tool's 
drive socket 26 for reception of a router bit 32. 
In the exemplary prior art power tool 20 depicted in FIG. 1, it will be 
observed that the base plate 28 is configured with two (2) opposed 
parallel flat sides 34, 35 and a pair of opposed rounded ends 36, 38 of 
circular arc configuration. Base plate 28 is further provided with 
integral collars or sleeves 39 defining a pair of spaced passages which 
are parallel to the flat sides 34, 35 of the base plate 28 and which are 
adapted to slidably receive respective different ones of a pair of guide 
rods 40, 41 which can be located in selected fixed positions relative to 
the base plate 28 by means of thumb screws 42 or the like. As here shown, 
the guide rods 40, 41 are non-symmetrical with respect to the tool's 
integral base plate 28--i.e., they are adjusted to project laterally to 
the left of the router 20 as viewed in FIG. 1--and serve to support a guide 
assembly, generally indicated at 44, which can be adjustably mounted on 
the guide rods 40, 41 by means of thumb screws 45. 
For all practical purposes relative to an understanding of the present 
invention, it will be appreciated that the conventional prior art router 
20 depicted by way of example in FIG. 1 is substantially similar in 
design, construction and operation to that shown in the aforesaid Cowman 
U.S. Pat. No. 4,718,468 except that in such patent the router's integral 
base plate, also indicated at 28, is circular in plan view having a pair 
of integral oppositely directed lateral extensions defining areas where 
the guide rods can be fixedly, yet adjustably, secured; whereas, in the 
conventional router 20 depicted in FIG. 1, the base plate 28, while 
generally circular, has two (2) flatted sides 34, 35 with the guide rods 
40, 41 being fixedly, yet adjustably, secured to the base plate 28 inboard 
of, and parallel with, the flatted sides 34, 35. As the ensuing 
description proceeds, those skilled in the art will appreciate that the 
particular shape of the tool's integral base plate 28 is irrelevant to the 
invention, provided only that the auxiliary base plate defining means of 
the invention is provided with a through opening, preferably complemental 
to, and suitable for receiving and surrounding, the particular integral 
base plate on the tool being used. In the illustrative form of the 
invention, the auxiliary base plate defining means is formed as a pair of 
complemental auxiliary base plate members adapted to be disposed in 
edge-to-edge abutting relation with the through opening defined by 
oppositely facing cut-outs formed in the opposed abutting edges. 
Consequently, where the tool's integral base plate 28 is circular, the 
cut-outs in the auxiliary base plate members will preferably be 
semi-circular; where the tool's integral base plate is square, the 
cut-outs will preferably be rectangular; etc. 
Thus, in accordance with one of the important aspects of the present 
invention, the conventional router 20 depicted in FIG. 1 is adapted for 
use with support means comprising an auxiliary base plate assembly, 
generally indicated at 46 in FIG. 2, which here takes the form of a pair 
of left and right mating, auxiliary base plate members 46L, 46R which are 
adapted to be mounted on the guide rods 40, 41 in lieu of the guide 
assembly 44 depicted in FIG. 1. To this end, the auxiliary base plate 
members 46L, 46R are provided with oppositely facing, complemental 
cut-outs 48L, 48R, respectively, in their respective abuttable edges 49L, 
49R, which cut-outs 48L, 48R are complemental in shape to, and designed to 
receive and snugly enclose, the left and right portions of the tool's 
integral base plate 28 as viewed in FIG. 2. 
As will be evident from inspection of FIG. 2, the left and right auxiliary 
base plate members 46L, 46R are each provided with a pair of parallel, 
horizontally oriented, through bores 50, 51 dimensioned and positioned to 
slidably receive respective ones of the left and right ends of the guide 
rods 40, 41 which are here shown as being affixed to the tool's integral 
base plate 28 and which project symmetrically to the left and right 
thereof. If desired, one or both of the auxiliary base plate members 46L, 
46R can be provided with an additional alignment pin 52 projecting 
laterally from the abutting edges 49L, 49R and positioned to be received 
within an alignment opening or bore 53 formed in the abutting edge 49R 
(and 49L where the alignment bore is not visible) of the opposite 
auxiliary base member 49R, 49L. 
The manner of assembly of the auxiliary base plate members 46L, 46R to the 
conventional prior art router 20 will be best understood by consideration 
of FIGS. 3 through 7. Thus, after removal of the guide assembly 44 (FIG. 
1) from the guide rods 40, 41, centering of the guide rods 40, 41 relative 
to the tool's integral base plate 28, and placement of the tool's base 
plate 28 and the left and right auxiliary base plate members 46L, 46R on a 
suitable flat surface (not shown) in the manner depicted in FIG. 2, one or 
the other, or both, of the left and right auxiliary base plate members 
46L, 46R are slidably interengaged with respective ones of the left and 
right projecting ends of the guide rods 40, 41 by insertion of such 
respective ends into the bores 50, 5 formed in the left and right 
auxiliary base members 46L, 46R; and, the respective auxiliary base 
members 46L, 46R are then slid along the guide rods 40, 41 until the left 
and right halves of the tool's integral base plate 28 are received in 
respective ones of the left and right cutouts 48L, 48R. 
Considering first FIG. 3, it will be noted that the left auxiliary base 
plate member 46L is fully seated on the guide rods 40, 41 in snug 
surrounding relation to the left half of the tool's integral base plate 
28; while the right auxiliary base plate member 48R is ready for assembly. 
In FIG. 4, it will be noted that both the left and right auxiliary base 
plate members 46L, 46R are partially mounted on the guide rods 40, 41 with 
the alignment pins 52 on the abutting edges 49L, 49R of the auxiliary base 
plate members positioned for insertion into the alignment bores 53 in the 
opposite edge 49R (the alignment bore 53 in edge 49L not being visible). 
Finally, and as shown in FIG. 5, the left and right auxiliary base plate 
members 46L, 46R are fully mounted on the guide rods 40, 41 in snug 
surrounding relation to the router's integral base plate 28 with their 
respective abuttable edges 49L, 49R in edge-to-edge abutting relation. 
It will, of course, be appreciated that the bores 50, 51 formed in the 
auxiliary base plate members 46L, 46R are positioned therein such that 
when the assembled router 20 and auxiliary base plate 46 are inverted as 
shown in FIG. 6, the lower surface 54 of the tool's integral base plate 28 
and the upwardly facing surfaces 55L, 55R of the auxiliary base plate 
members 46L, 46R all lie in a smooth, continuous, uninterrupted common 
plane; and, where only the router bit 32 extends above that plane for 
cutting engagement with any work piece (not shown) positioned on the 
assembled base plate elements 28, 46L, 46R. 
The thus assembled conventional router 20 and auxiliary base plate assembly 
46 as depicted in FIGS. 6 and 7 is now in readiness for drop-in mounting 
in a suitable work bench. Thus, as best shown in FIG. 8, a shop work 
bench, generally indicated at 56--which may be either a large fixed 
stationary work bench or a small portable work bench--is provided with a 
through rectangular opening 58 bounded by a peripheral flange 59 recessed 
beneath the work surface 60 of the work bench 56 by a depth equal to the 
thickness of the auxiliary base plate assembly 46. In keeping with this 
aspect of the invention, the flanged recessed opening 58 is designed so as 
to snugly receive the rectangular auxiliary base plate assembly 46 without 
freedom for lateral and/or rotational relative movement therebetween. In 
the illustrative form of the invention, this is achieved by utilizing a 
rectangular auxiliary base plate assembly 46 and a complemental 
rectangular through opening 58 in the work bench 56. However, those 
skilled in the art will appreciate that the auxiliary base plate assembly 
46 and the complemental through opening can be of other than rectangular 
configuration--for example, they can be triangular, hexagonal or of other 
polygonal shape, or they can be ellipsoidal or any other non-circular 
complemental configuration--provided only that the configuration chosen 
precludes relative lateral and/or rotational movement therebetween, thus 
stabilizing the router 20. 
Consequently, when the assembled and inverted router 20 and auxiliary base 
plate assembly 46 are dropped into the flanged through opening 58, the 
peripheral edges of the auxiliary base plate 46 rest on, and are supported 
by, the work bench's peripheral flange 59 with the bottom surface 54 of 
the inverted router integral base plate 28, the upwardly facing surfaces 
55R, 55L of the auxiliary base plate members 46R, 46L, and the upwardly 
facing surface 60 of the work bench 56 all lying in a smooth, continuous, 
uninterrupted, common horizontal plane upon which work pieces (not shown) 
can be placed for cutting engagement with the router's upwardly projecting 
router bit 32 as best shown in FIG. 9. Moreover, since the auxiliary base 
plate assembly 46 is snugly received within the complementally shaped 
flanged opening 58, movement of the auxiliary base plate members 46L, 46R, 
guide rods 40, 41, and router 20 relative to one another and relative to 
the work bench 56 is effectively precluded, even in those instances where 
the thumb screws 42 (FIG. 2) used to secure the tool's integral base plate 
28 to the guide rods 40, 41 are loosened due to vibration of the tool in 
usage. 
Those skilled in the art will appreciate from the foregoing Detailed 
Description that there has herein been disclosed a simple, yet highly 
effective, rugged and economical arrangement for permitting effective, 
rapid and easy conversion of a conventional portable power tool to a 
stationary table-top unit which is totally devoid of separate clamps, 
support brackets and similar threaded fasteners. The tool 20, auxiliary 
base plate assembly 46 and work bench 56 can be quickly assembled merely 
by: i) removal of the tool's guide assembly 44 (FIG. 1); ii) sliding the 
left and right auxiliary base plate members 46L, 46R onto the guide rods 
40, 41; iii) inverting the tool/auxiliary base plate assembly 20/46; and 
iv), dropping the inverted tool/auxiliary base plate assembly 20/46 into 
the flanged opening 58 in the work bench 56. When it is desired to again 
use the power tool 20 as a portable power tool, it is merely necessary to 
remove the tool/auxiliary base plate assembly 20/46 from the work bench 
opening 58, slide the left and right auxiliary base plate members 46L, 46R 
off the guide rods 40, 41, and, if desired, the guide assembly 44 can be 
remounted on the guide rods 40, 41.