Router guide and clamping apparatus

A combined router guide and clamping apparatus for enabling the routing of small rectangular holes, grooves, recesses, rabbets, mortices and tenons, in a controlled and precise manner, on large or small blocks of wood as well as the sides or ends of boards. The combined router guide and clamping apparatus comprises: a working platform having a platform area for receiving a router base thereon; a base unit secured to the working platform, underneath the working platform and including clamping means, which includes at least one adjustable clamp, moveable relative to the working platform, for securing a workpiece in the base unit relative to the working platform; and a fence means on the working platform and including at least one adjustable fence for guiding the router base on the router platform area. The clamping assembly includes a pair of clamping jaws and front and rear force transfer bars which isolate the clamping forces from the working platform and the base unit.

FIELD OF THE INVENTION 
This invention relates to a combined router guide and clamping apparatus 
for enabling the routing of small rectangular holes, grooves, or recesses, 
in a controlled and precise manner, on large or small blocks of wood as 
well as the sides or ends of boards. In particular, the present invention 
provides an integral clamping apparatus which is self-contained and does 
not depend in any way on its mounting base for the transfer of any force. 
BACKGROUND OF THE INVENTION 
When routing small rectangular holes, grooves, or recesses into small 
blocks of wood, or onto the sides or ends of boards, it is desirable to 
include an integral clamping assembly which can be readily adjusted so 
that a precise cut can be made. 
One example of a prior art design is found in Spielman, P., The New Router 
Handbook (New York: Sterling Publishing Co., 1993) at pp. 352-354. This 
prior art device, referred to as The WoodRat.TM., consists of a large 
horizontal extruded-aluminum body or base. Inside this horizontal 
extruded-aluminum body is another extrusion which functions as a 
work-holding carriage. As shown in illus. 32-20 to 32-23, and as explained 
at p. 353, the combination of router movement and/or workfeed movement 
provides the necessary flexibility to produce numerous controlled joinery 
cuts. While this prior art device is suitable for forming a variety of 
tenons and other types of joints onto the ends of boards, it does not 
appear to be particularly suited for clamping and routing onto very small 
or thin workpieces. That is to say, due to the nature of the clamping 
action, it would seem that the workpiece would need to be of sufficient 
thickness so that the full length of the jaws contacts the workpiece, 
which would rule out the clamping of small blocks and thinner workpieces 
on this device. Furthermore, the jaws of the clamping assembly are 
oriented substantially vertically so that workpieces cannot be easily 
positioned for routing operations along their length. In order to do so, 
it would appear that a workpiece would have to be held horizontally and be 
clamped only by its two ends, which would require that the ends of the 
workpiece be made true and perpendicular to its length for a reliable 
grip. Also the length of the workpiece would be limited by the maximum 
distance between the Woodrat.TM. jaws. As well, the jaws of the clamping 
assembly appear to be metal and they will have to be located sufficiently 
below the router baseplate so that the blade of the router will not make 
contact with them when passing underneath. Additionally, the movement that 
the router can make in order to form the tenons and various other types of 
joints is limited. Finally, the WoodRat.TM. is a wall mounted device which 
is not easily portable. 
SUMMARY OF THE INVENTION 
The present invention provides an apparatus for clamping boards and large 
or small blocks of wood to enable the routing of small rectangular holes, 
grooves, recesses, rabbets, mortices, and tenons, in a controlled and 
precise manner. 
In a first aspect, the present invention provides an apparatus for use with 
a portable router having a base and a router bit extendable from said 
base, the apparatus comprising: 
(1) a working platform having a platform area for slidably supporting a 
router base thereon and defining an opening for access, in use, to a 
workpiece; 
(2) a base unit secured to the working platform, underneath the working 
platform and including clamping means comprising a pair of opposed and 
adjustable clamping jaws, each of which is, movable relative to the 
working platform, for securing said workpiece in the base unit in one of a 
plurality of lateral positions relative to the opening in the working 
platform; and 
(3) a fence means on the working platform and including at least one 
adjustable fence for guiding the router base on the platform area. 
In the preferred embodiment, the working platform defines an opening for 
receiving a workpiece. Additionally, the fence means comprises a plurality 
of fences positionable around the opening, for guiding a router on any 
side of a workpiece. 
Preferably, the opening in the working platform is generally rectangular 
and includes a front edge and a rear edge, wherein the clamping jaws 
comprise a front clamping jaw and a rear clamping jaw and wherein the 
clamping means includes screw means engaging the front and rear clamping 
jaws, for displacing the front clamping jaw away from the front edge and 
the rear clamping jaw away from the rear edge, to clamp a workpiece. 
In the preferred embodiment, the screw means comprises, for each of the 
clamping jaws, a pair of threaded rods rotatably mounted in the base unit 
and engaging threaded bores in the corresponding clamping jaw for movement 
thereof. 
The screw means comprises a first pair of parallel threaded rods engaging 
the rear clamping jaw and including adjustment handles at the front of the 
apparatus, and a second pair of threaded rods, parallel to one another and 
to the first pair of threaded rods engaging the front clamping jaw, and 
including adjustment handles at the rear of the apparatus. 
In one preferred embodiment, the first pair of parallel threaded rods are 
located outside of the second pair of parallel threaded rods, and all of 
the parallel threaded rods are located generally coplanar and below the 
working platform. 
Each of the clamping jaws is generally rectangular, the front clamping jaws 
including clearance holes for passage of the first pair of threaded rods 
and the rear clamping jaws including clearance holes for passage of the 
second pair of threaded rods. 
More preferably, the base unit comprises a base plate and front and rear 
force transfer bars secured thereto, wherein the working platform is 
secured on top of the force transfer bars. 
Advantageously, the front handles include bearing surfaces for abutting the 
front force transfer bar, the rear handles include bearing surfaces for 
abutting the rear force transfer bar, the first pair of threaded rods 
include compression collars for abutting an inside surface of the rear 
force transfer bar and the second pair of threaded rods includes 
compression collars for abutting the inside of the front force transfer 
bar, the compression collars being adjusted so that loads applied to the 
threaded shafts from the clamping jaws are distributed by the handles and 
the compression collars between the front and rear force transfer bars.

DETAILED DESCRIPTION OF THE INVENTION 
Note that, for the purposes of this patent specification, the entire 
clamping and platform apparatus is also referred to as the "masterguide". 
Referring to FIGS. 1, 2A and 2B, the masterguide or apparatus has a 
platform area 1 which has a large rectangular hole 2 at its center. All 
routing activity is contained within the rectangular hole 2. A standard 
hand-held router, having a 6" diameter baseplate, would sit and slide 
around in the middle of the platform area 1, where it would be limited and 
controlled by each of four adjustable fences 6. In the platform area 1 
underneath each adjustable fence 6 is a pair of slots 8. Each adjustable 
fence 6 is slidable along the length of each pair of slots 8. 
Now referring to FIGS. 2A, 2B, and 3, glued onto the underside of the 
platform area 1 is a backing plate 20 which also has a large rectangular 
hole 2 at its center. The backing plate 20 and platform area 1 together 
form a working platform 110. The backing plate 20 has wide slots 21 (shown 
in FIGS. 5 and 9) located underneath each of the slots 8 in the platform 
area 1. These wide slots 21 accommodate the heads of T-nuts 9 which screw 
onto the tips of flat-headed machine screws 7 each passing through an 
adjustable fence 6, a slot 8, and a wide slot 21, to secure each 
adjustable fence 6 onto the platform area 1. However, each of the 
adjustable fences 6 is free to move back and forth until the flat-headed 
machine screws 7 are tightened. Referring back to FIG. 2B, eight small 
holes 13 located around the perimeter of the platform area 1 are provided 
so that the working platform 110 can be screwed down directly onto a 
workpiece if desired, when the working platform 110 is used independently 
from base unit 120. 
Still referring to FIGS. 2A, 2B, and 3, located in each of the four corners 
on top of the platform area 1 are clampdown plates 3 which are fastened 
onto the platform area 1 by means of flat-headed machine screws 4. A 
clearance hole 18 is drilled through each triangular clampdown plate 3, 
and extends also through the platform area 1 and the backing plate 20. 
Four screw knobs 5 are placed in the clearance holes 18 and then screwed 
into threaded holes 19 located in four attachment plates 22 of the base 
unit 120. While the working platform 110 and the base unit 120 are usually 
fastened together, as explained, the working platform 110 can also be used 
independently. 
Now referring to FIGS. 2A, 3, and 11, the base 26 of the base unit 120 also 
has a large rectangular hole 47 at its center, which substantially matches 
the rectangular hole 2 of the working platform 110. Located on top of the 
base 26 are two clamp mounting blocks 27 which serve to raise the entire 
clamp assembly above the base 26. Attached onto the clamp mounting blocks 
27 are the front and rear force transfer bars 24 and 25, both of which are 
channel-shaped. The front and rear force transfer bars 24 and 25, as well 
as the two clamp mounting blocks 27, are fastened to the base 26 by means 
of the flat-headed machine screws 46. Located inside each end of the front 
and rear force transfer bars 24, 25 are the front and rear bearing plates 
36, 38 which are fastened onto the force transfer bars 24, 25 by means of 
flat-headed machine screws 37. Located in the middle area between the 
front and rear force transfer bars 24, 25 are the front and rear clamp 
jaws 14, 15, the ends of which rest on the clamp mounting blocks 27. 
Now referring to FIGS. 4-8, and 11, recessed into the backs of the front 
and rear clamp jaws 14, 15 are the front and rear jaw plates 39, 41 which 
are fastened onto the clamp jaws 14, 15 by means of flat-headed wood 
screws 40. 
Front handles 10 are attached to the outer threaded rods 34 which pass 
through clearance holes in the front force transfer bar 24 and in the 
front bearing plates 36. These threaded rods 34 then pass through 
clearance holes in the front jaw plates 39, then through loose clearance 
holes 42 in both the front and rear clamp jaws 14, 15, before screwing 
into threaded holes in the rear jaw plates 41. The far ends of the outer 
threaded rods 34 finally pass through clearance holes in the rear bearing 
plates 38 and in the rear force transfer bar 25, which acts as a bearing. 
The rear handles 12 are attached to inner threaded rods 35, which pass 
through clearance holes in the rear force transfer bar 25 and in the rear 
bearing plate 38. These threaded rods 35 then pass through clearance holes 
in the rear jaw plates 41, then through loose clearance holes 42 in both 
the front and rear clamp jaws 14, 15, before screwing into threaded holes 
in the front jaw plate 39. The far ends of the inner threaded rods 35 
finally pass through clearance holes in the front bearing plates 36 and in 
the front force transfer bar 24, which again acts as a bearing. 
The front handles 10 operate the rear clamp jaw 15, and the rear handles 12 
operate the front clamp jaw 14. Located internally from each front handle 
10, and rear handle 12, are washers 11 (FIGS. 7 and 8). Also, located near 
the front handles 10 on the outer threaded rods 34 are limit collars 44 
which limit the amount of excess movement by the outer threaded rods 34, 
and by the rear clamp jaw 15. Similarly, near the rear handles 12 on the 
inner threaded rods 35 are limit collars 44 which limit the amount of 
excess movement by the inner threaded rods 35, and by the front clamp jaw 
14. 
Still referring to FIGS. 4-8, and 11, located near the far ends of the 
outer threaded rods 34 are compression collars 45. These compression 
collars 45 are strategically placed so that they will contact the rear 
bearing plates 38 at precisely the same instant that the front handles 10, 
via washers 11, contact the front force transfer bar 24. Similarly, near 
the far ends of the inner threaded rods 35 are compression collars 45. 
These compression collars are strategically placed so that they will 
contact the front bearing plates 36 at precisely the same instant that the 
rear handles 12, via washers 11, contact the rear force transfer bar 25. 
All of the limit collars 44, and all of the compression collars 45, are 
fastened onto the threaded rods 34 and 35 by means of pins or screws 43. 
This arrangement of the collars 45 is intended to ensure that loads from 
the jaws 14, 15 are transferred evenly to the front and rear force 
transfer bars 24, 25. 
Now referring to FIG. 9, the front and rear clamp jaws 14, 15 are V-notched 
16 on their forward sides for the clamping of round workpieces. In FIG. 
10, each front and rear clamp jaw 14, 15 is shown with calibration 
markings on both sides of center line 17. The calibration markings and a 
center line 33 on the top surface of each mounting block 27 are provided 
to indicate the front to rear positions of the clamp jaws 14,15. The four 
attachment plates 22 are fastened onto the tops of the front and rear 
force transfer bars 24, 25 by means of flat-headed machine screws 23. 
Located underneath the front and rear force transfer bars 24, 25 is a 
removable tray 28 which slides in between the two clamp mounting blocks 27 
to cover the large rectangular hole 47 in the center of the base 26. 
Now referring to FIGS. 11 and 12, the removable tray 28 has been removed to 
show the large rectangular hole 47 in the center of the base 26. The 
removable tray 28 is shown in various views in FIGS. 13A-13C. 
At each end of the removable tray 28 is a slot 29 which is used to secure 
the tray 28 when it is installed into the base unit 120. The tray 28 can 
be slid into the base unit 120 in either direction, or upside down. 
Referring back to FIG. 11, located in the middle of the front force 
transfer bar 24 is a turn button 30, which is fastened onto the front 
force transfer bar 24 by means of a special round-headed machine screw 32 
with a shoulder. This is so that the turn button 30 will be free to rotate 
when the special screw 32 is fully tightened. The back surface of the turn 
button 30 has soft plastic 31 glued onto it. The soft plastic 31 provides 
some resistance so that the turn button 30 will stay in any position, but 
it will also allow the turn button 30 to be turned manually. When the turn 
button 30 is turned vertically, it will fit into the slots 29 of the 
removable tray 28 and lock the tray 28 in place. When the turn button 30 
is turned horizontally, the removable tray 28 can be installed or removed. 
For smaller workpieces, the removable tray 28 can be installed. For larger 
or longer workpieces which would project below the removable tray 28, the 
tray 28 is removed. Clamping longer workpieces vertically in the 
masterguide is possible by placing the masterguide over an open area, as 
explained further below. 
Normally, the masterguide is placed on a work surface, such as a table, for 
use. Shown in FIG. 12 are four rubber feet 48 which are fastened onto the 
base 26 by means of round-headed wood screws 49. These rubber feet 48 
raise the base 26 up above the work surface and also help prevent the 
masterguide from sliding around on the work surface during use. 
Now referring to FIG. 14, a diagram shows the basic principle of the double 
acting clamp assembly of the present invention. The primary task of the 
front and rear clamp jaws 14, 15 is to hold the workpiece tightly and 
securely, but they also enable the workpiece to be centered in the work 
area defined by the large rectangular hole 2 (as shown in FIG. 2A). The 
front handles 10 are attached to the outer threaded rods 34 which pass 
through clearance holes in the front and rear force transfer bars 24, 25, 
as well as through the loose clearance holes 42 in the front and rear 
clamp jaws 14, 15. The rear jaw plates 41, which are attached to the rear 
clamp jaw 15, each have a threaded hole in them to engage the outer 
threaded rods 34 so that the position of the rear clamp jaw 15 is 
controlled by means of the front handles 10. The rear handles 12 are 
attached to the inner threaded rods 35, which pass through clearance holes 
in the front and rear force transfer bars 24, 25, as well as through the 
loose clearance holes 42 in the front and rear clamp jaws 14, 15. The 
front jaw plates 39, which are attached to the front clamp jaw 14, each 
have a threaded hole in them to engage the inner threaded rods 35 so that 
the position of the front clamp jaw 14 is controlled by means of the rear 
handles 12. The outer threaded rods 34 pass through clearance holes in the 
front jaw plates 39, and the inner threaded rods 35 pass through clearance 
holes in the rear jaw plates 41. 
Still referring to FIG. 14, the limit collars 44 located on all of the 
threaded rods 34, 35 serve to limit any excess movement of the threaded 
rods 34, 35, as well as of the front and rear jaws 14, 15. The compression 
collars 45, located near the far ends of the outer threaded rods 34, are 
precisely positioned so that each will contact the rear force transfer bar 
25 exactly when its associated front handle 10 contacts the front force 
transfer bar 24. Similarly, the compression collars 45, located near the 
far ends of the inner threaded rods 35, are precisely positioned so that 
each will contact the front force transfer bar 24 exactly when its 
associated rear handle 12 contacts the rear force transfer bar 25. This 
means that, effectively, if any handle is pushed against its force 
transfer bar, it will at the same time push its compression collar 45 
against the other force transfer bar. 
In summary, the double action clamp assembly locks into place when the 
front and rear clamp jaws 14, 15 tighten against the workpiece. When a 
front handle 10 is tightened, it pushes against the front force transfer 
bar 24, and pulls the rear jaw plate 41 and the rear jaw 15 toward it, so 
that the threaded rod 34 between them goes into a state of tension. At the 
same time, the associated compression collar 45 pushes against the rear 
force transfer bar 25, and the section of the threaded rod 34, between the 
compression collar 45 and the rear jaw plate 41, goes into a state of 
compression. The rear handles 12 perform exactly the same function with 
the threaded rods 35, but in the opposite direction. This results in 
tension and compression forces 50 that are equal in each of the four 
corners of the double acting clamp assembly. Effectively, these forces 
cancel out at the force transfer bars 24 and 25. Consequently, the 
clamping action is completely self-contained, and is not dependent in any 
way on the mounting base for the transfer of any force. 
Because the threaded rods 34, 35 pass through the middle at each end of the 
clamp jaws 14, 15, the clamping action is balanced. This ensures that 
there is no tendency for the clamp jaws 14, 15 to twist when tightened 
fully onto the workpiece. Preferably, the front and rear force transfer 
bars are channel-shaped to resist any bending action. 
The workpiece can be repositioned towards the front of the working region 
by loosening the two rear handles 12, and then tightening the two front 
handles 10. To position the workpiece towards the rear of the working 
area, the reversed procedure can be followed. In addition, the workpiece 
can be removed and replaced at any time by loosening and tightening the 
front handles 10 only. This way, the workpiece will always retain its 
front to rear position. 
Now referring to FIGS. 15, and 15A-15D, a fence range extender 50A is shown 
which extends the forward reach of one of the adjustable fences 6. An 
angle bracket 52 fits into a partial recess in the top of a fence block 
51. The angle bracket 52 and fence block 51 are fastened together by means 
of flat-headed wood screws 53. Located inside the front section of the 
angle bracket 52 is a steel plate 54, which is fastened to the angle 
bracket 52 by means of special flat-headed machine screws 55 that have 
small diameter pin extensions on them, as best shown in FIG. 15C. At each 
end of the clamping plate 56 are guide holes that slide along the small 
diameter pin extensions of the special flat-headed machine screws 55. A 
special round-headed machine screw 58 is screwed into a threaded hole in 
the center of the steel plate 54. The threaded hole in the steel plate 54 
has a matching clearance hole in the front section of the angle bracket 
52. The special round-headed machine screw 58 has been machined so that it 
has a small diameter pin extension with a circlip groove in it. The small 
diameter pin extension of the round-headed machine screw 58 passes through 
a matching clearance hole in the center of the clamping plate 56. A washer 
and circlip 59 are then installed to link them together (FIG. 15D). 
Finally, rubber pads 57 are glued onto the forward side of the clamping 
plate 56 to act as buffers. 
Now referring to FIGS. 16 and 16A-16F, a reference stop 60A is shown which 
can be installed in any location on either of the masterguide clamp jaws 
14, 15. The reference stop 60A has a very low profile so that it will fit 
underneath the working platform 110 without causing obstruction. A 
channel-shaped bracket 63 is recessed into the top and the rear of a 
reference block 62. The channel-shaped bracket 63 and the reference block 
62 are fastened together by means of flat-headed wood screws 64. Located 
outside on the front of the channel-shaped bracket 63 is a steel plate 65 
which is fastened onto the channel-shaped bracket 63 by means of two 
special flat-headed machine screws 66 which have small diameter pin 
extensions on them as best shown in FIG. 16B. A clamping plate 67 is 
positioned opposite the steel plate 65. The clamping plate 67 includes two 
guide holes which slide along the small diameter pin extensions of the 
special flat-headed machine screws 66. An adjustment screw 69 is screwed 
into a threaded hole in the center of the steel plate 65. The threaded 
hole in the center of the steel plate 65 has a matching clearance hole in 
the channel-shaped bracket 63. Attached to the adjustment screw 69 is an 
adjustment knob 60 which has tight-fitting rubber tubing 61 around it for 
better grip. The other end of the adjustment screw 69 has been machined so 
that it has a small diameter pin extension with a circlip groove in it as 
best shown in FIG. 16A. The small diameter pin extension of the adjustment 
screw 69 passes through a matching clearance hole in the center of the 
clamping plate 67. A washer and circlip 70 are then installed to link the 
adjustment screw 69 to the clamping plate 67. Finally, rubber pads 68 are 
glued onto the clamping side of clamping plate 67 to act as buffers. 
Now referring to FIGS. 17 and 17A-17C, a long mount 71 is shown. FIGS. 23 
and 24 show a pair of long mounts 71 being used to support a workpiece so 
that the workpiece is mounted evenly between the clamp jaws 14, 15. The 
long mounts 71 fit down between the inner threaded rods 35 and rest on top 
of the two clamp mounting blocks 27. The long mounts support the workpiece 
so that it is held by only the upper half of the clamp jaws 14, 15 and 
such that, if it were long enough and horizontally mounted, the underside 
of the workpiece would just clear the tops of the four threaded rods 34, 
35 without touching them. Also, if the workpiece is very narrow, only one 
long mount 71 is required between the clamp jaws 14, 15. The notch 72 
provides clearance for equalizing plates which will be described in 
further detail below. Note that the long mounts 71 only provide support 
for the workpiece and are not part of the clamping action. 
Now referring to FIGS. 18 and 18A-18C, a short mount 73 is shown. FIGS. 25 
and 26 show a pair of short mounts 73 being used to support very thin or 
very small workpieces. As shown in FIGS. 25 and 26, the workpieces are 
mounted evenly by resting them on each shallow shelf 74. Alternatively, 
the short mounts 73 can be turned the other way up so that the workpieces 
will fit evenly, but lower down, by resting on each deeper shelf 75. 
Whichever shelf 74, 75 is facing downwards will accommodate equalizing 
plates to be described in further detail below. In the case of the short 
mounts 73, they are part of the clamping action. 
Now referring to FIGS. 19A-19E, platform height extenders are shown. When 
it is necessary to raise the working platform 110 higher above the base 
unit 120, either to accommodate thicker workpieces horizontally or to 
provide greater clearance above the clamp jaws 14, 15, the height 
extenders 76, 77, 78 can be used. Each size of platform height extender 
76, 77, 78 operates as a set of four which have screw ends 79 that screw 
directly into threaded holes 19 in the four attachment plates 22 of the 
base unit 120 (shown in FIGS. 2A and 3). Either used separately or in 
combination, these platform height extenders 76, 77, 78 allow the working 
platform 110 to be raised in 1/2" steps up to 31/2" above the standard 
height. The working platform 110 is then fastened to the platform height 
extenders 76, 77, 78 by means of the four screw knobs 5 which screw into 
threaded holes 80, as shown in FIG. 24. Optionally, the platform height 
extenders, 76, 77, 78 can be knurled or hexagonal in shape for better 
grip. 
Now referring to FIGS. 20 and 20A-20D, whenever a workpiece is to be held 
in the masterguide by means of only the upper half of the clamp jaws 14, 
15 (such as when the long mounts 71 or short mounts 73 are used) then the 
holding power of the double action clamp assembly would be compromised due 
to the twisting action that would take place, unless some form of 
equalization is applied to the lower half of the clamp jaws 14, 15. In the 
present invention, this is done by placing an equalizing plate which has 
the same clamping width as the workpiece onto the removable tray 28 in 
between the two clamp jaws 14, 15. A typical equalizing plate 89 is shown 
in FIGS. 21A-21C, which can be used in either direction to provide 
equalization of 23/4" or 3". A whole series of equalizing plates can be 
made in this manner to cover the complete range of clamping widths from 
1/2" up to 6" in steps of 1/4". Various other sizes of equalizing plates 
81-88 are shown in FIG. 20. FIGS. 23 and 24 show equalizing plates 83 and 
89 being used, respectively. 
For clamping widths that fit in between each 1/4" step an equalizing shim 
91 (shown in FIGS. 20 and 22A-22C) can be used in conjunction with an 
equalizing plate 81-89, as shown in FIGS. 25 and 26. The equalizing shim 
91 has a 1/8" thickness and is bent at one end 92 for ease of handling, 
and also to stand on its edge. A thinner equalizing shim 90 (shown in FIG. 
20), which is 1/16" thick, is also provided so that one or both equalizing 
shims 90, 91 can be used in conjunction with an equalizing plate 81-89 to 
enable the complete range of clamping width to be covered in steps of 
1/16". 
For convenience, the small equalizing plates 81-89 can be stored in a 
slotted stand that would fit into a suitable box. The slotted stand, as 
shown in FIGS. 20 and 20A-20D, includes all of the equalizing plates 81-89 
that cover the range from 1/2" up to 3". Also included in the set are the 
two equalizing shims 90-91 as well as the two short mounts 73. The slotted 
stand comprises a slotted upper panel 93 and a matching recessed base 94. 
The slotted upper panel 93 and recessed base 94 are fastened together by 
means of flat-headed wood screws 96 in conjunction with four spacers 95. 
In order to span an adequate length of each clamping jaw 14, 15, all 
equalizing plates 81-89 have at least one dimension which is equal to or 
greater than 21/2". There are six larger equalizing plates (not shown) 
that cover the range from 31/4" up to 6". These larger equalizing plates 
can be stored with the long mounts 71 in a separate box. 
Now referring to FIG. 27, the principle of operation for using the 
masterguide is illustrated, with the four adjustable fences 6 being 
represented by the rectangular border 97, and the cutting line 98 
representing the proposed rectangle that is to be routed on the workpiece. 
The four fences 97 of the masterguide each have to be positioned a 
specific distance away from the cutting line 98 on the workpiece. This 
distance can be referred to as the setback distance 99. The area that lies 
between the four fences 97 of the masterguide and the cutting line 98 can 
be called the fence zone 100 which is shown as a shaded area in FIG. 27. 
If a groove 101 cut by a router bit 102 is required to be on the side of 
the cutting line 98 that is not inside the fence zone 100, then it is 
called an "outside cut". However, if another groove 103 cut by another 
router bit 104 is required to be on the side of the cutting line 98 that 
is inside the fence zone 100, then it is called an "inside cut". Actual 
routing should always be done in a clockwise direction around the four 
fences of the masterguide, regardless of whether it is to be an "outside 
cut" or an "inside cut". Furthermore, all cuts in the workpiece should be 
routed not more than 1/8" at a time, until the required depth is reached. 
"Outside cuts" are used for the routing of grooves, slots, holes, and 
recesses in a workpiece. "Outside cuts" can also be used for routing 
rabbets if desired. For "outside cuts", after the perimeter of any hole or 
recess has been routed in a clockwise direction, any remaining internal 
area that needs to be removed can then be routed in a random manner. Also, 
for routing grooves or slots that will have the same width as the diameter 
of the router bit, it will only require the use of one fence with perhaps 
two other fences to act as end stops. 
"Inside cuts" are used for the routing of tenons, and they are also used 
for a preferred method of routing rabbets. Any type of tenon can be routed 
in one operation if the workpiece is mounted vertically in the 
masterguide, and all sides of the tenon are routed in turn, using "inside 
cuts". Four-sided tenons will require the use of all four fences, each 
fence being set back the appropriate distance from the cutting line on the 
workpiece. Two-sided tenons will require the use of two opposing fences, 
each being set back the appropriate distance from the cutting line of the 
workpiece. The other two fences are set back out of the way, so that the 
router bit can move completely off the workpiece at each end of the tenon. 
Whenever fences are set back out of the way, they should be set at their 
safeguard positions. This means that the fences are set so that they will 
prevent the router bit of the router from getting too close to the edges 
of the working area, and risking damage to the working platform 110. 
Three-sided tenons will require the use of three fences, each fence being 
set back at an appropriate distance from the cutting line on the 
workpiece, with the fourth fence being set back to its safeguard position. 
The actual routing for "inside cuts" will preferably be done using a large 
diameter router bit in the router, say 3/4". The routing is done in a 
clockwise direction, inside the four fences, to cut each side of the tenon 
in turn. When cutting tenons using an "inside cut", the base of the router 
must be held against each fence in turn to prevent any damage to the tenon 
being routed. This is not difficult because there is a natural tendency 
for the router to move towards each fence due to the torque from the 
router bit. An additional advantage to using "inside cuts" for making 
tenons is that the router bit uses an inward cutting action to rout each 
side of the tenon, which virtually guarantees that no breakouts will 
occur. 
If a shelf is required on the tenon, this can be accomplished without 
requiring any further adjustment of the fences by placing a fence buffer 
(essentially a block of wood measuring 3/4".times.3/4".times.5") against 
the fence where the shelf is required. That fence is adjusted prior to 
routing with a fence buffer in place. After the tenon has been routed, the 
fence buffer can be removed to rout the shelf region of the tenon. 
In addition, rabbets can be routed using an "inside cut" to take advantage 
of an inward cutting blade to minimize the chance of breakouts. This is 
done by performing the routing operation using a right to left motion 
along the fence located in front of the rabbet being routed, instead of 
the usual left to right direction along a fence located behind the rabbet 
being routed using "outside cuts". 
The masterguide is also capable of routerplaning the top surface of 
workpieces which are clamped between the jaws. In this case, all four of 
the adjustable fences 6 will be set back out of the way to their safeguard 
positions. A large diameter router bit, perhaps 3/4" in diameter, should 
be used for routerplaning. The router is moved in a clockwise direction, 
with the router bit only partly on the workpiece, in order to rout the 
outside perimeter of the workpiece surface, and then the remaining area 
can be routed in a random manner. This method of routerplaning ensures 
that no breakouts will occur because the outside perimeter of the 
workpiece is routerplaned using an inward cutting action of the router 
bit. 
As described earlier, the working platform 110 can be raised if necessary 
by means of platform height extenders 76, 77, 78, to enable thicker 
workpieces to be mounted horizontally in the masterguide. Also, by raising 
the working platform 110, more clearance is provided between the router 
bit and the clamp jaws, thus avoiding the possibility of the clamp jaws 
being damaged. Thinner workpieces, on the other hand, can be clamped 
securely by means of the long mounts 71 or short mounts 73 described 
earlier, with or without raising the working platform 110, depending on 
the type of cut that is to be made. Whenever a fence 6 is required to be 
positioned such that it will control the routing on a workpiece near the 
far side of the working area 2, then the fence range extender 50A 
(described earlier) can be attached to that fence 6 prior to it being 
adjusted. If a workpiece needs to be clamped and unclamped several times, 
the reference stop 60A described earlier can be installed at any desired 
location on either of the clamp jaws 14, 15 to provide a common reference 
point. 
Longer workpieces can be vertically mounted on the masterguide by placing 
the masterguide over an open area. This can be done by placing the 
masterguide in a position to straddle two planks, or the open jaws of a 
portable folding bench, such as a Black & Decker Workmate.TM.. Thus, the 
longer workpiece will project below the masterguide and in between the 
planks or the open jaws of a Workmate.TM.. 
In normal operation, the workpiece should be clamped so that its top 
surface is approximately flush with the top surface of the working 
platform 110. In some cases, this will not be possible (such as for long 
horizontally mounted workpieces) in which case, the workpiece should be 
made approximately flush with the bottom surface of the working platform 
110. However, the top surface of the workpiece should never project above 
the top surface of the working platform 110 as it would interfere with the 
smooth operation of the router. Also, the proposed working area on the 
workpiece should be approximately centered in the middle of the working 
platform 110, by adjusting the front and rear handles 10, 12 of the 
masterguide. Unless it is required to be otherwise, the workpiece should 
be made square in the masterguide by ensuring that the clamp jaws 14, 15 
are set squarely in the base unit 120. If the clamping jaws are not set 
squarely, this can be corrected by adjusting the front and rear handles 
10, 12 on the right side only, or on the left side only, and by 
referencing the calibration marks on the clamp mounting blocks 27. If the 
front to rear location of the workpiece needs to remain unchanged, then 
the workpiece can be removed and installed using only the two front 
handles 10 of the base unit 120. 
All adjustments to the fences of the masterguide can be easily made, both 
for "outside cuts" and "inside cuts", and for all sizes of router bits, by 
means of the setback gauges described in the inventor's co-pending patent 
application Ser. No. 09/207,759. 
The maximum working area possible with the exemplary embodiment described 
in this patent specification is 41/4".times.41/4", which requires a 
rectangular hole in the working platform 110 of 41/2".times.41/2". With 
this size of rectangular hole in the working platform 110, any tipping 
action that might occur (when using a standard 6" diameter hand-held 
router) would tend to lift the blade of the router away from the workpiece 
surface. If the rectangular hole in the working platform 110 were made any 
larger than this size, any router tipping action that might occur could 
then also tend to let the blade of the router cut deeper into the 
workpiece surface. However, it is possible to make a larger version of the 
masterguide that would have a working area of 61/4".times.61/4", and a 
rectangular hole measuring 61/2".times.61/2", which would be suitable for 
a standard 8" diameter hand-held router. 
While the particular embodiment of the present invention has been 
illustrated and described, it would be obvious to those skilled in the art 
that various other changes and modifications can be made without departing 
from the spirit and scope of the invention. It is therefore intended to 
cover in the claims all of such changes and modifications that are within 
the scope of this invention.