Archery bow limb adjustment bolt

A limb adjustment bolt for a compound archery bow includes a threaded shank for releasably attaching a limb to a handle portion of the bow. One end of the shank is connected to a generally circular flange which in turn is attached to a head of the bolt. The head is generally rectangular in cross section and has a longitudinal axis which is perpendicular to the longitudinal axis of the shank. A central portion of the head tapers outwardly and is attached to the flange. The head can include a threaded aperture for receiving a couterweight. Furthermore, the bolt can be formed of a separate head and shank.

BACKGROUND OF THE INVENTION 
The invention relates to archery bows, in general, and in particular to an 
adjustment bolt for attaching a bow limb to a handle member of a compound 
bow. 
In a standard bow, the force with which the arrow is dispatched is 
dependent upon the resilience of the limbs of the bow. An archer's bow 
will have a pound rating varying from about fifteen to one hundred pounds. 
When the rating gets above about thirty-five pounds, it requires a rather 
strong person to pull the bow back to the release position and to hold the 
position as the arrow is aimed prior to release. 
In a compound bow construction, the pull on the bow string is high at the 
beginning of the draw, but the human arm at this point is able to exert a 
maximum force. As the draw progresses a little beyond mid-point, there is 
an over center action on eccentric pulleys which decreases the draw force 
needed to maintain the bow string in a drawn position without decreasing 
the energy stored in the limbs of the bow. Thus, at full draw, it is 
relatively easy to hold the bow and the bow string and much easier to 
perfect the aiming technique and the proper finger release. 
The bow limbs are typically attached to the handle member by adjustment 
bolts. Rotation of the adjustment bolts provides a range of angular 
relationships between the bow limbs and the handle with corresponding 
differences in the amount of force imparted to the arrow for a given pull 
distance on the draw string. In the prior art, the heads of these 
adjustment bolts have been provided with a hexagonal aperture. Thus, an 
Allen wrench must utilized to rotate the bolts to either change the force 
of the bow or to disassemble the bow for travel. It is relatively 
inconvenient to locate the proper Allen wrench each time it is needed and 
there is always the chance that the Allen wrench can be lost at a time 
when it is most needed. 
SUMMARY OF THE INVENTION 
The present invention involves a bow limb adjustment bolt having a head of 
a size and shape whereby it is capable of being grasped between the thumb 
and forefinger of a human hand to enable force adjustments and ease of 
disassembly of the bow. The head is of generally rectangular cross section 
with a longitudinal axis perpendicular to the longitudinal axis of the 
shank of the bolt. The center of the head tapers outwardly into a flange 
at the connection to the head. The bolt head can have a threaded aperture 
formed in its top surface for accepting a threaded end of a balancing 
weight device. The adjustment bolt also can be a single piece unit or be 
constructed of a separate head and shank. Furthermore, the flange can have 
indicia formed thereon for indicating the desired amount of rotation for 
changing the force on the drawstring.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
There is shown in FIG. 1 a compound bow 11 including a central handle 
portion 12 having an upper limb 13 and a lower limb 14 releasably attached 
thereto. A pair of limb adjustment bolts 15 according to the present 
invention are threaded through the inner ends of the limbs 13 and 14 and 
threadably engage the end portions of the handle 12. Rotating the 
adjustment bolts to move them inwardly or outwardly relative to the handle 
12 causes the corresponding limb to pivot about an attachment point 
thereby changing the angle of the limb relative to the handle and changing 
the force required to pull a drawstring 16 a predetermined distance from 
the handle 12. Opposite ends 17 and 18 of the drawstring 16 are attached 
to the outer ends of the upper limb 13 and lower limb 14 respectively. The 
drawstring extends from the end 17 around a cam 19 rotatably mounted at 
the outer end of the lower limb 14. The other end 18 of the drawstring 16 
is attached to the outer end of the lower limb 14 and extends around a cam 
20 rotatably mounted at the outer end of the upper limb 13. With the 
exception of the adjustment bolts 15, the aforementioned compound bow is 
of conventional construction and operates in a known manner. 
The adjustment bolt 15 according to the present invention is shown in FIGS. 
2 through 5. The bolt 15 includes a shank 21 having threads 22 formed 
thereon from a lower end to an upper end portion 23 which is unthreaded. 
The upper end of the end portion 23 is attached to a head 24 of the bolt 
15. The head 24 has a lower flange portion 25 with a relatively planar 
lower surface 26 to which the upper end portion 23 of the shank 21 is 
attached. A central portion 27 of the head 24 tapers downwardly and 
outwardly from a substantially vertically extending pair of front and back 
walls 28 and 29 of a handle portion of the head 24. The handle portion of 
the head 24 is generally rectangular in cross section and has a 
longitudinal axis which extends generally perpendicular to the 
longitudinal axis of the shank 21. The front wall 28 and rear wall 29 are 
joined by a pair of end walls 30, a bottom wall 31, and a top wall 32. The 
junctions of all of the walls are rounded to eliminate any sharp corners. 
Furthermore, the bottom wall 31 is tapered from the end walls 30 
downwardly to the flange 25. 
Although the bolt 15 according to the present invention can be made in 
various sizes, the following dimensions have been found suitable for most 
compound bows commercially available. The distance between the end walls 
30 is approximately two and one quarter inches. The distance between the 
front wall 28 and the rear wall 29 is approximately five-eights of an inch 
and the distance between the bottom wall 31 and the top wall 32 at the end 
walls 30 is approximately three quarters of an inch. The distance between 
the lower planar surface 26 and the top wall 32 is approximately seven 
eights of an inch. The flange 25 is approximately one and one quarter 
inches in diameter and the shank 21 is approximately two inches in length. 
The threads 22 can be five sixteenths inch in diameter with eighteen 
threads to the inch. 
There is shown in FIG. 6 a top plan view of an alternate embodiment of the 
adjustment bolt according to the present invention. An adjustment bolt 33 
has a head 34 including a flange 35 and a top wall 36. A threaded aperture 
37 is formed in the head 34 with an opening in the top wall 36. The 
longitudinal axis of the threaded aperture 37 is the same as the 
longitudinal axis of the shank portion (not shown) of the bolt 33. The 
shank portion is similar to the shank portion of the bolt 15. The threaded 
aperture 37 is typically one quarter inch in diameter with twenty threads 
to the inch. The threaded aperture 37 accepts most commercially available 
stabilizers such as shown in FIG. 10. 
An adjustment bolt 38 according to a second embodiment of the present 
invention is shown in FIG. 7. The adjustment bolt 38 includes a shank 39 
and a separate head 40. The shank 39 includes a portion having threads 41 
formed thereon from a lower end to an end connected to an enlarged 
diameter upper portion 42 by a chamfered portion 43. The upper end of the 
upper portion 42 has an aperture 44 formed therein which can be configured 
to engage an Allen wrench. 
The head 40 has an aperture 45 centrally formed in a top wall 46 thereof. 
The aperture 45 extends through the head 40 and is tapered at 47 to a 
smaller diameter to provide a seat for the chamfered portion 43 of the 
shank 39. The head 40 has a pair of end walls 48 each of which has a 
threaded aperture 49 formed therein extending to the aperture 45. Each of 
the apertures 49 threadably accepts an Allen screw 50 which is then 
threaded into engagement with the outer surface of the upper portion 42 of 
the shank 39 to maintain the shank within the aperture 45. 
There is shown in FIG. 8 an alternate embodiment of the shank 39 utilized 
in the adjustment bolt 38 of FIG. 7. A shank 51 includes threads 52 formed 
from a lower end to an area adjacent an upper end portion 53. The upper 
end portion 53 is attached to an outwardly tapering portion 54 having an 
aperture 55 formed in an upper surface thereof suitable for engaging an 
Allen wrench. The tapered portion 54 cooperates with the tapered portion 
47 of the aperture 45 formed in the head 40 of the embodiment shown in 
FIG. 7. The upper larger diameter portion of the aperture 45 is threaded 
to accept a plug in the form of an Allen screw 56 which is threaded into 
contact with the tapering portion 55 to maintain the shank in the aperture 
45. 
There is shown in FIG. 9 a second alternate embodiment of a shank suitable 
for use with the head 40 of FIG. 7. A shank 57 has threads 58 formed 
thereon from a lower end to a central unthreaded portion 59. The central 
portion 59 is attached to an outwardly tapered portion 60 which in turn is 
attached to a larger diameter upper end portion 61. The side wall of the 
upper end portion 61 can have a depression or aperture 62 formed therein 
for cooperating with one of the Allen screws 50 shown in FIG. 7. 
Furthermore, an upper surface 63 of the upper end portion 61 can have a 
threaded aperture 64 formed therein for retaining a stabilizer such as 
shown in FIG. 10. 
In FIG. 10, the adjustment bolt 33 is adapted to retain a stabilizer 65. 
The threaded aperture 37 formed in the adjustment bolt 33 retains a 
threaded end of a shaft 66 of the stabilizer 65. The opposite end of the 
shaft 66 is attached to an enlarged diameter counterweight 67. The 
stabilizer 65 is utilized to balance the bow when the drawstring and an 
arrow are in the desired position for firing. Also, indicia 68 can be 
formed on the outwardly facing surface of the flange 25 and/or upper taper 
portion 27 for cooperation with one or more locations on the bow to 
indicate force settings. 
In accordance with the provisions of the patent statutes, the present 
invention has been described in what is considered to represent its 
preferred embodiment. However, it should be noted that the invention can 
be practiced otherwise than as specifically illustrated and described 
without departing from its spirit or scope.