Log coping jig

A machine for cutting a cope or kuda in the end of a log has a base member that is secured to a longitudinal side of the log. A support member is attached to the base member. A sleeve is associated with the support member, and an elongate shaft extends longitudinally through an elongate opening through the sleeve. A router is attached to the elongate shaft near one end of the shaft. The sleeve is pivotally mounted to the support member so that the longitudinal axis of the elongate shaft that extends through the sleeve can be set to any desired, acute angle of up to 90 degrees with the longitudinal axis of the log. The shaft can be moved longitudinally back and forth through the sleeve, and the shaft can also rotate about its longitudinal axis. This allows the router to be moved back and forth over the end of the log to cut an incurved, cylindrical cut into the end of the log, with the axis of the cylindrical cut being set at any desired degree of slope relative to the longitudinal axis of the log.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a machine for cutting a cope at the end of 
a turned log rail. The cope, or "kuda", as it is called in some areas, is 
a curved cut which allows the log rail to be joined (by means of lag bolts 
in counter-bored holes) to vertical posts. The joint thus formed is tight 
and aesthetically pleasing. 
2. State of the Art 
It is the common practice of skilled artisans to hand cut the cope or kuda 
in the end of the log rail by means of conventional, hand tools such as 
coping saws and chisels. There has been no suggestion, to the best of the 
present inventor's knowledge, of a specialized tool for use with a router 
for cutting the cope or kuda in the end of a log rail. 
OBJECTIVES AND SUMMARY OF THE INVENTION 
It is an object of the invention to provide a log coping jig which can be 
situated on a log rail, with the end of the log rail being subjected to 
the action of a router bit which is moved in an arcuate motion across the 
end of the log in accordance with the constraints of the various 
components of the jig of the present invention. 
It is another object of the invention to provide a log coping jig with 
router and means for cutting a controlled, arcuate cope or kuda in the end 
of the log such that the end of the log will form an aesthetic 
intersection with a post irrespective of whether the log intersects the 
post at a 90 degree angle or any angle less than 90 degrees. 
It is a further object of the invention to provide a log coping jig with 
router wherein the router bit is allowed to move in two directions 
simultaneously, with the first movement being linear and with the second 
movement being arcuate in a plane that is substantially perpendicular to 
the first, linear movement. 
It is yet another object of the invention to provide a log coping jig with 
router that includes a base member that is to be secured to the log, with 
means being provided to allow the coping jig and router to be adjusted 
within a limited range along the base member in either direction of the 
log's length. 
In accordance with the present invention, a machine is provided for cutting 
a cope or kuda in the end of a log. The machine has a base member that is 
secured to a longitudinal side of the log. A jig is attached to the base 
member, and a router is secured to the jig. The jig, as will be fully 
explained hereinafter is adapted to guide the bit of the router in a two 
motions that can be performed simultaneously. The first motion is a linear 
movement of the bit, and the second motion is an arcuate movement of the 
bit in a plane that is substantially perpendicular to the first, linear 
motion. 
Additional objects and features of the invention will become apparent from 
the following detailed description, taken together with the accompanying 
drawings.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS 
Like reference numerals designate like parts in those figures of the 
drawings in which they occur. Electrical conductors, a workbench, and some 
balance springs have been omitted from the drawings for clarity. 
The base component 40 (shown by itself in FIG. 2A) is intended to clamp to 
the workpiece 10, such as a turned log, by the use of adjustable band 
clamps 11a. The base component 40 is composed of a piece 12 of 3/4" birch 
plywood that is formed to a right angle. The piece 12 is fastened to two 
aluminum right angle braces 13 for strength. The ends 11 of the base 
component 40, as shown in FIGS. 1 and 2A, are rounded to accept the band 
clamps 11a. On top of the piece 12 of plywood is fastened a solid maple 
piece 14 which is formed with a groove 15 on either side. A sectional view 
is pictured in FIG. 9. 
An arm support component 42 (shown by itself in FIG. 2B) sets on top of the 
base component 40 and is composed of a solid maple piece 16 sandwiched 
between the two sides 17 which are formed of 1/2" birch plywood. The arm 
support component 42 is fixed securely vertically and laterally by the 
tenons 18 (FIGS. 2B and 9) which fit into the grooves 15 in the base 
component 40 (FIGS. 2A and 8) and slides longitudinally unless locked down 
by use of the knob 19. The sides 17 are slotted in an arc 20 for reasons 
presently described. 
An arm component 44 (shown by itself in FIG. 2C) fits in between the sides 
17 of the arm support component 42 as shown in FIG. 1. The arm component 
44 is composed of three major parts. A sleeve 21 is a solid maple 
rectangular shaped member with a hole drilled through the length of it. A 
shaft 22, also of solid maple, is turned to a diameter to fit snugly but 
easily through the long hole in the sleeve 21. A router 23 is fastened to 
the lower end of the shaft 22. The axis of the router 23 is oriented 
perpendicular to the axis of the shaft 22. 
The sleeve 21 is also provided with two smaller holes at right angles to 
the long hole. The lower of these holes, shown by the numeral 24 in FIG. 
2C, accommodates a bolt through the sleeve 21 and the sides 17 of arm 
support component 42. This allows the arm component 44 to rotate radially 
in a vertical plane parallel with the long direction of the base component 
40 and workpiece 10 (turned log). The other of the holes in the sleeve 21, 
shown by the numeral 25 in FIG. 2C, accommodates a bolt and knob 26 that 
extends through the sleeve 21 and sides 17 of the arm support component 
42. The bolt and knob 26 slide in the slot 20 and may be tightened to 
secure the arm support component 42 in any position within an arc of 90 
degrees. 
A router 23 is fastened on the end of the shaft 22. By being mounted on the 
shaft 22, the router can be moved in two different motions, either one at 
a time or simultaneously. The first motion is a linear motion in which the 
router 23 and its bit move in a linear motion in a direction that is 
parallel to the axis of the shaft 22. This motion is accomplished by 
sliding the shaft 22 up and down within the sleeve 21 as indicated by the 
double arrowed line identified by the numeral 22a in FIGS. 2 & 4. The 
other or second motion of the router 23 and its bit is an angular rotation 
movement that is accomplished pivoting the router 23 about the axis of the 
shaft 22 in a plane perpendicular to the axis of the shaft 22, as 
indicated by the double arrowed line identified by the numeral 22b in 
FIGS. 3 & 5. 
The router 23 is also adjustable by screw rotation and clamp to provide a 
range of radii from the center of the shaft 22 to the cutting surface of 
the bit 27, as shown in FIG. 7. At the minimum setting 28 a radius of 3" 
is obtained; at the maximum setting 29 a radius of 6" is obtained, 
resulting in a diameter range from 6" to 12". Therefore posts 30 (FIG. 10) 
of similar sizes can be intersected, resulting in a tight joint 34. 
Operation 
In operation, a workpiece 10 (turned log of any diameter from 2" to 12") is 
placed on a workbench and secured. A rough cut is made by other means to 
approximately 2" from the final cut line. The base component 40 of the 
apparatus of the present invention is placed upon the workpiece 10 and 
clamped thereon with the band clamps 11a. The correct angle between the 
longitudinal center axis of the base component 40 and the sleeve 21 is 
established and then set by the knob 26. 
A stop 31, sliding with the slot 20, is brought to bear against the sleeve 
21 and secured. Then the shaft 22 of the arm component 44 is backed off 
sufficiently (that is, the angular distance is decreased between the 
sleeve 21 and the base component 40) to allow a pass to be made over the 
end of the workpiece 10 with the router 23 such that a portion of the wood 
is routed off. A pass involves the operator grasping the two handles 32 of 
the router 23, depressing two trigger switches to energize the router 23, 
then manually moving the router 23 and shaft 22 down and up while rotating 
it, to pass over the entire surface 33. Subsequent resettings of the shaft 
22 of the arm component 44 to larger angles, and repasses with the router 
23 will result in the final cut. It will typically take three or four 
passes to return to the stop 31, which is the originally set angle. The 
final cut obtains a surface which is straight in the vertical plane 
parallel to the long axis of the workpiece 10, and curved in a direction 
normal to that. 
That completes the operation. The work-piece 10 can then be counter-bored 
35 and fastened in place to the matching vertical post 30. Other 
applications are undoubtedly possible with the device, such as balusters, 
the vertical members between rails in a staircase. 
Obviously the invention is susceptible to changes or alterations without 
defeating its practicability. The prototype model is constructed of the 
wood materials described herein; later production models probably would be 
of metal. Although a preferred embodiment of the apparatus of the present 
invention has been illustrated and described, it is to be understood that 
the present disclosure is made by way of example and that various other 
embodiments are possible without departing from the subject matter coming 
within the scope of the following claims, which subject matter is regarded 
as the invention.