Cast cutter and method

An assembly and method for cutting through a cast of the type having flexible wrapping and a rigid outer shell. The assembly comprises a side plate having edges defining an elongate notch for receiving the cast, a cutting blade rotatably mounted on the side plate adjacent the notch, and means for rotating the cutting blade relative to the side plate. The edges of the side plate defining the notch include at least one cutting portion. The cutting blade is maintained in sliding scissors-like engagement with the cutting portion of the side plate to shear the cast between the cutting portion and the cutting blade as the blade is rotated.

This invention relates generally to a cutter, and more particularly to a 
cast cutter that is adapted to cut through a cast of the type having a 
rigid shell and soft or flexible wrapping underlying the shell. 
BACKGROUND OF THE INVENTION 
Casts of the type used to set broken bones, for example, are made of 
plaster, as well as various synthetic resin materials, such as the 
fiberglass/resin composite sold under the trademark "SCOTCHCAST" by the 
Minnesota Mining and Manufacturing Company of St. Paul, Minn. U.S.A., 
and/or described, for example, in U.S. Pat. Nos. 4,502,479; 4,609,578; 
4,667,661; 4,705,840 and 4,774,937. Advantages of fiberglass/resin 
composite materials include gas permeability, light weight, and 
transparency to X-rays. 
Casts ordinarily consist of a tubular stockinet or an elongate strip or 
bandage that is placed or wrapped, for example, around a patients injured 
limb, a layer of synthetic cast padding wrapped around the stockinet, and 
a plurality of layers of the fiberglass-resin composite or plaster 
material wrapped around the padding to form a rigid shell. Such cast 
padding and stockinet is typically made from very flexible woven or 
nonwoven materials, such as cotton, polyester or other fibers. Cast 
padding and stockinet will sometimes be collectively referred to herein as 
"wrapping". 
Cast shells have typically been removed by using powered oscillating saws, 
which are noisy and may create a substantial quantity of dust. In order to 
prevent injury to the patient, these saws are usually adapted to be 
oscillated at a high frequency and low amplitude. Despite that precaution, 
the saw can cause burns or cuts in some situations, and notwithstanding 
any actual danger, patients, especially small children, may be frightened 
by the saw. U.S. Pat. No. 4,637,391 (Schlein) describes a surgical saw 
blade for cutting plaster or fiberglass casts. That saw blade is adapted 
to oscillate at high frequency (e.g., 12,000-14,000 oscillations per 
minute) and low amplitude. An adjustable depth stop is provided to limit 
the depth that the saw blade may cut. 
U.S. Pat. No. 4,421,111 (Rothman) describes a surgical cast cutter that 
includes a saw blade that is oscillated at low amplitude to prevent injury 
of the patient. That cutter includes the feature of vacuum exhaust of dust 
particles created in cutting the cast. British Patent No. 2 068 829 
(Saito) and U.S. Pat. No. 4,543,718 (Duescher) describe other cast cutters 
employing oscillatory motion and vacuum exhaust of dust particles. 
In addition to the creation of dust, one problem with oscillating cast 
cutters is that typically they do not cut through the soft layers or 
wrapping of the cast. This is because the low amplitude, high frequency 
motion of the blade is usually ineffective against soft tissue or fabric. 
As a result, the soft layers or wrappings underlying the cast are 
typically removed as a separate step after cutting the cast. For example, 
U.S. Pat. No. 3,365,798 (Cunningham) describes a device for cutting the 
soft wrappings underlying plaster casts after the shell has been cut. That 
device includes a shoe which may be positioned between the wrappings and 
the patient and two inwardly-facing intersecting blades that cut the 
wrapping as the device is pushed or pulled through a slot cut in the cast. 
Another method of protecting a patient from the saw blade of a cast cutter 
has been to place a guard between the patient and the saw blade. For 
example, U.S. Pat. Nos. 2,344,262 (Odierna et al.) and 2,366,017 (Fortune) 
describe powered cast cutters including a guard or shoe for protecting the 
patient from the saw blade, with the guard or shoe separating the saw 
blade from the patient's skin. The shoe of those cutters are placed under 
the cast (i.e., between the cast and the patient's skin). 
U.S. Pat. No. 590,163 (Pearson) describes a manually operated cast cutting 
tool having a guard for protecting the patient from the saw blade. That 
guard includes a foot that is positioned between the cast and the flesh of 
the patient. A crank-arm is provided for manually rotating the saw blade. 
U.S. Pat. No. 2,571,527 l(Boyer) shows another cast cutter having a guard 
that is placed between the cast and the patient. U.S. Pat. No. 2,217,923 
(Silverman) shows powered and manually operated cast saws that include a 
guide shoe having a semi-circular groove for receiving the saw blade to 
accommodate different thicknesses of casts. 
U.S. Pat. No. 1,269,373 (Brinck) describes a cutting device having a shield 
plate that is slipped between the cast and the patient, and a circular 
cutting member that is movable relative to the shield plate as the cast is 
cut. That device includes a crank for rotating the cutting member, and a 
pin to limit motion of the cutting member toward the shield plate as the 
cast is cut. 
U.S. Pat. No. 2,232,733 (Scarboro) shows a powered cast remover that 
includes a guard that separates the saw blade from the patient and a 
suction fan for removing the cuttings and placing them in a container. 
While cast cutting devices that employ a guard between the cast and the 
patient and a conventional rotary saw blade may efficiently, quietly and 
safely cut the rigid shell of the cast, it has been found that they are 
ineffective at cutting the flexible wrappings underlying the shell. The 
wrappings are frequently caught by the teeth of the saw blade and wrapped 
around the axle of the saw blade, with the result that such devices have 
typically become jammed on the cast shortly after starting the cut (e.g., 
within 4-6 inches (100-150 mm)). 
U.S. Pat. No. 4,611,585 (Steidle) describes a cast cutter that includes a 
fixed center blade that is positioned between the cast and patient and two 
motor-driven oscillating blades disposed along opposite sides of the 
center blade. That cutter includes a movable cover hood which apparently 
ensures that the blades are only exposed when the blades are applied to 
the plaster cast itself. 
Casts have also been cut by embedding wire in the cast material when 
forming the cast, and pulling the wire to cut the cast. For example, U.S. 
Pat. No. 4,290,424 (Wahl et al.) and British Patent No. 2 003 391 (Lampke 
et al.) show cutting wires that are embedded in the material of the cast. 
See, also, West German Patent No. 3 342 918 (Strang). 
SUMMARY OF THE INVENTION 
An assembly of the invention is designed to cut completely through a cast 
of the type typically having flexible wrapping(s) and a rigid shell in a 
single cutting operation. Among other things, the assembly is designed to 
reduce the production of "saw dust" when cutting casts, and preferably to 
be driven by manual power. 
Generally, the assembly comprises a side plate having edges defining an 
elongate notch for receiving the cast, and a cutting blade rotatably 
mounted on the side plate generally adjacent the notch. The side plate's 
edges defining the notch include at least one cutting portion, and the 
cutting blade is maintained in sliding scissors-like engagement with the 
cutting portion of the side plate to shear the wrapping and shell between 
the cutting portion and the cutting blade as the cutting blade is rotated. 
Means is provided for rotating the cutting blade relative to the cutting 
portion of the side plate. 
Preferably, the cutting blade is adapted to both cut through the rigid 
shell by removing material from the shell with the action of a saw blade 
and to shear through the soft or flexible wrappings underlying the shell, 
and possibly a portion of the shell, in a manner similar to the action of 
scissors. 
The method according to the invention generally comprises maintaining the 
cutting blade of the assembly in sliding scissors-like engagement with the 
cutting portion of the side plate, and introducing a portion of the cast 
into the notch of the side plate and into contact with the cutting blade, 
with a portion of the side plate separating the cutting blade from the 
patient. The cutting blade is then rotated relative to the cutting portion 
of the side plate to shear the wrapping and shell between the cutting 
portion and cutting blade, and the apparatus is advanced through the cast 
as the cutting blade is shearing the cast. Finally, the cast is removed 
from the patient's limb after the cast has been cut. 
Other features will be pointed out hereinafter.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
An assembly of the invention is indicated generally by the reference 
numeral 10, and is adapted for cutting through a cast 12 of the type 
typically having flexible wrapping 14 and a rigid shell 16. As used 
herein, "wrapping" refers to any type of soft or flexible material that 
underlies the shell 16 of a cast 12, and typically includes a layer of 
stockinet and a layer of padding of polyester woven, knit or nonwoven 
material. 
As shown in FIG. 1, the assembly 10 generally comprises a side plate 18 
having edges generally designated 20 defining an elongate notch 22 for 
receiving the cast 12, and a cutting blade 24 rotatably mounted on the 
side plate 18 adjacent the notch 22. Means (e.g., crank arm 26) is 
provided for rotating the cutting blade 24 relative to the side plate 18. 
The edges 20 defining the notch 22 include at least one cutting portion 
28. The cutting blade 24 is maintained in sliding scissors-like engagement 
with the cutting portion 28 of the side plate 18 to shear the wrapping 14 
and shell 16 between the cutting portion 28 and the cutting blade 24 as 
the cutting blade 24 is rotated. 
More specifically, the side plate 18 has forward and rearward ends 30 and 
32, and a finger 34 extending generally forwardly from the body 36 of the 
side plate 18. An edge 28 of the finger 34 forms the cutting portion 28 of 
the side plate 18. As shown in FIG. 9, the cutting portion 28 of the edge 
28 is smooth and sharp, and preferably formed at an angle A-1 only 
slightly less than ninety degrees (e.g., 87-89 degrees). As illustrated in 
FIG. 3, the finger 34 is adapted to be placed between the wrapping 14 of 
the cast 12 and the patient 40 to protect the patient 40 from the cutting 
blade 24 and to facilitate tensioning and shearing the wrapping 14 between 
the cutting portion 28 and the teeth 66 of the cutting blade 24. 
The "left" major surface of the side plate 18, which is the surface in 
sliding engagement with the cutting blade 24, is substantially flat and 
smooth. The words "right", "left", "rightwardly" and "leftwardly" are used 
herein merely for convenience, and are used in reference to the intended 
direction of motion of the assembly 10 indicated by the arrow 41 in the 
figures. "Rightwardly" refers to the upward direction in FIG. 2, and 
"leftwardly" refers to the downward direction in FIG. 3. "Forward" or 
"forwardly" refer to the direction indicated by the arrow 41 in FIG. 3, 
and "rearward" or "rearwardly" refer to the direction opposite the arrow 
41. 
The means for rotating the cutting blade 24 preferably comprises the 
manually operable crank arm 26 shown in FIGS. 1-3, 7 and 8, although a 
powered drive motor (not shown) or any other suitable drive mechanism 
could alternatively be provided for rotating the cutting blade 24. An axle 
42 is rotatably mounted through a self-lubricating bearing or bushing 44 
in the side plate 18. The cutting blade 24 is mounted adjacent one end of 
the axle 42, and the crank arm 26 is releasably mountable on the axle 42 
adjacent the other end thereof. The bushing 44 and the axle 42 are 
preferably formed of dissimilar metals to reduce frictional wear between 
the axle 42 and bushing 44. For example, the bushing 44 may be formed of 
brass, and the axle 42 formed of hardened steel. The bushing 44 may be 
either press fit or threadably received in a bore through the side plate 
18. 
Most preferably, the crank arm 26 includes a ratchet mechanism 46 so that 
the crank arm 26 may be ratcheted relative to the axle 42 to rotate the 
axle 42 and cutting blade 24, and a handle 48 is provided extending 
forwardly from the side plate 18 to facilitate operation of the crank arm 
26 and pulling the side plate 18 forwardly through the cast 12 as the 
crank arm 26 is operated. 
As shown in FIGS. 1-3, the crank arm 26 and ratchet mechanism 46 may take 
the form of a conventional socket wrench (at 26). A wrench of this type 
typically has an offset handle (at 26), a four-sided male drive piece (not 
shown), and the ratchet mechanism 46 for ensuring that the drive piece 
rotates in only one direction as the handle 26 is reciprocated as 
indicated by the arrow designated 50 in FIG. 3. The ratchet mechanism 46 
may be of the type that can be adjusted to reverse the action of the 
mechanism 46 to permit rotating the drive piece in the other direction, 
although a ratchet mechanism 46 that can only be driven in one direction 
is preferred (e.g. for clockwise rotation of the cutting blade 24 as 
indicated by arrow 52 in FIGS. 1 and 8). 
A spring-loaded bearing (not shown) is spring biased laterally outwardly 
from the drive piece of the crank arm 26 to securely and releasably mount 
a conventional socket 54 (FIG. 2) on the drive piece. An elongate 
extension or rod (not shown) may be provided between the drive piece and 
the socket 54 in the event that movement of the crank arm 26 would 
otherwise be restricted. A plurality (e.g., 4-6) of such extension rods of 
various lengths may be provided with the assembly 10, with the operator of 
the assembly 10 selecting the appropriate extension rod and mounting it 
between the socket 54 and the drive piece of the crank arm 26. 
The right end of the axle 42 (the upper end in FIG. 2) is tightly and 
securely received in the socket 54, and preferably has a polygonal (e.g., 
hexagonal) configuration complementary to a polygonal (hexagonal) cavity 
in the socket 54. The socket 54 may be permanently or semi-permanently 
mounted on the right end of the axle 42, for example, by an "Allen" or 
internal "hex" head bolt received in a coaxial threaded bore in the axle 
42. 
The axle 42 preferably includes an enlarged diameter cylindrical portion 
(not shown) and a smaller diameter cylindrical portion (not shown) 
extending coaxially leftwardly from the enlarged portion (in the direction 
toward the cutting blade 24), with both the enlarged and smaller diameter 
portions being rotatably received in the bore of the bushing 44. The left 
shoulder (not shown) of the enlarged portion of the axle 42 and a 
complementary shoulder in the bore of the bushing 44 prevent axial 
movement of the axle 42 in the leftward direction away from the socket 54 
(downwardly in FIG. 2). The smaller diameter cylindrical portion is housed 
in the portion of the bushing 44 that is received in the side plate 18. 
The cutting blade 24 is mounted on a polygonally-shaped mounting portion of 
the axle 42 that extends axially leftwardly (downwardly in FIG. 2) from 
the smaller diameter cylindrical portion of the axle 42. Most preferably, 
the mounting portion of the axle 42 has a generally square-shaped cross 
section that corresponds to a square-shaped opening through the center of 
the cutting blade 24, and a threaded left end portion extends axially 
outwardly from the square-shaped portion for threadably receiving a 
conventional lock nut 56 or other suitable fastener. The cutting blade 24 
and/or the lock nut 56 prevent axial movement of the axle 42 in the 
rightward direction toward the socket 54 (upwardly in FIG. 2). 
The cutting blade 24 and axle 42 may alternatively be formed in one 
integral piece, in which case the configuration of the axle 42 would be 
changed to permit assembly. As used herein, "integral" and "one piece 
construction" refer to a single part that is manufactured in a single 
continuous piece, as opposed to parts that are assembled from component 
parts. The axle and drive piece (not shown) of the ratchet mechanism may 
also be integrally formed as one continuous piece, in which case the 
socket 54 would be eliminated from the assembly. 
Regardless of the particular construction of the axle 42 and cutting blade 
24, it is desirable that they be rigidly fixed or connected together so 
that the desired relationship can be maintained between the cutting blade 
24 and the side plate 18. In this regard, it may also be noted that the 
internal shoulder (not shown) of the bushing 44 and the "left" shoulder of 
the enlarged cylindrical portion of the axle 24 prevent the cutting blade 
24 from moving away from the side plate 18. Alternatively or in addition, 
the central hub portion 72 of the cutting blade 24 may be spring biased 
toward the side plate 18 to help maintain the cutting blade 24 in 
engagement with the cutting portion 28 of the side plate 18. 
As shown in FIG. 1, the notch-defining edges 20 of the side plate 18 are 
generally U-shaped in side elevation, with generally parallel "legs" or 
edge portions (also at 20) extending generally forwardly from an arcuate 
end portion 58 to the forward end 30 of the side plate 18. The arcuate end 
portion 58 is positioned generally adjacent and below the axle 42 so that 
a portion of the cutting blade 24 is exposed through the notch 22. The 
elongate notch 22 and finger 34 may have lengths, for example, of 
approximately 30 mm between the arcuate end portion 58 and the forward end 
30 of the side plate 18. The distance between the parallel edge portions 
20 is sufficient to permit the cast 12, including the shell 16 and 
wrapping 14, to be placed through the notch 22 against the cutting blade 
24. For example, the distance between these parallel edge portions 22 may 
be approximately 17 mm. 
An arcuate channel 60 is formed in the right side of the side plate 18 
between the arcuate end portion 58 and the rearward end 32 of the side 
plate 18. The channel 60 is tapered outwardly in the rearward direction 
(rightwardly in FIGS. 1 and 5) from the notch 22 to the rearward end 32 of 
the side plate 18. For example, the arcuate channel 60 may be tapered at 
an angle A-2 of approximately 10 degrees. 
The taper of the arcuate channel 60 facilitates separating cut portions of 
the cast 12 by acting as a wedge to wedge the cut portions apart as the 
assembly 10 is advanced through the cast 12. This wedge-action of the 
channel 60 is believed to help prevent binding of the cutting blade 24 in 
the cast 12. The arcuate walls of the channel 60 also help guide the 
assembly 10 through the cast 12. More specifically, the walls of the 
channel 60 are preferably parallel to one another and spaced apart a 
distance substantially equal to the distance between the parallel edge 
portions 22. The walls of the arcuate channel 60 extend linearly 
rearwardly (rightwardly in FIGS. 1 and 8) from the parallel edge portions 
22 of the notch 20, and the surfaces forming the channel 60 are smoothly 
contoured in order to facilitate movement of the cut portions of the cast 
12 along the channel 60. 
As illustrated in FIG. 8, the longitudinal axis of the column 62 of the 
handle 48 may be conveniently offset at an angle A-3 of approximately ten 
degrees from the common longitudinal axis of the notch 20 and arcuate 
channel 60. While other orientations of the handle 48 relative to the 
notch 20 and arcuate channel 60 may be employed, the illustrated 
orientation is believed to be ergonomically effective in facilitating 
travel of the assembly 10, especially of the finger 34, through the cast 
12. The handle 48 preferably includes an ergonomically configured grip 
portion 64 extending generally perpendicularly from the forward end of the 
column 62 (leftward in FIG. 1). 
As illustrated in FIGS. 4 and 5, the cutting blade 24 is preferably of 
generally conical or frustoconical configuration, and includes a plurality 
of generally radially outwardly extending teeth 66. The "base" 68 of the 
conical or frustoconical blade 24 provides a substantially flat surface 
(also 68) in sliding engagement with the substantially flat right major 
surface of the side plate 18. 
At least one, but preferably three to five elongate recesses (e.g., recess 
70 in FIG. 1), are formed in the base 68 of the cutting blade 24. These 
recesses 70 are adapted to receive small amounts of cast dust or loose 
material to prevent jamming of the cutting blade 24. Alternatively, 
"cut-outs" or recesses (not shown) may be provided in the right major 
surface of the side plate 18. 
The teeth 66 of the cutting blade 24 are shown in the drawing (e.g., FIG. 
5) as being tapered in the radially outward direction toward the base 68. 
For example, the teeth 66 may be tapered at an angle A-4 of approximately 
35 degrees. The taper of the teeth 66 is believed to help maintain the 
teeth 66 in sliding scissors-like engagement with the right major surface 
and cutting portion 28 of the side plate 18. The taper of the teeth 66 
also helps to strengthen the teeth 66, since the teeth 66 are thicker in 
their radially inward direction. In any event, the cast shell 16 
preferably tends to urge the cutting blade 24 in the direction toward the 
side plate 18 to help maintain the teeth 66 in sliding scissors-like 
engagement with the cutting portion 28 of the side plate 18. 
The cutting blade 24 may conveniently have an outer diameter of 
approximately 55 mm, and an enlarged annular hub portion 72 having an 
outer diameter of approximately 20 mm. The leading edges 74 (FIG. 4) of 
the teeth 66 are preferably formed at an angle A-5 of approximately 20 
degrees with respect to radial lines extending radially outwardly from the 
axis of rotation of the cutting blade 24. The cutting blade 24 shown in 
FIG. 4 is designed to be rotated in the clockwise direction in the figure 
so that the teeth 66 move across the notch 20 toward the cutting portion 
28 of the side plate. The leading edges 74 are skewed at the angle A-5 in 
the trailing direction (counterclockwise in FIG. 4) radially outwardly 
along the cutting blade 24. 
The length of the leading edges 74 may be approximately 10 mm, and the 
teeth 66 are preferably slightly thicker along their leading edges 74 than 
along their trailing portion (e.g., between the leading edge 74 of one 
tooth 66 and the leading edge 74 of the next tooth 66. The teeth 66 are 
most preferably tapered in the trailing circumferential direction 
(counterclockwise in FIG. 4) from their leading edges 74 in order to 
prevent binding of the trailing portions of the teeth 66 in the material 
of the cast 12. 
The assembly 10 preferably cuts the cast 12 by simultaneously functioning 
both as a "saw" and as "shears". That is, the teeth 66 of the cutting 
blade 24 "saw" through the rigid shell 16 of the cast 12 by removing small 
portions of the material of the shell 16, and the teeth 66 of the cutting 
blade 24 "shear" the soft wrapping 14 by tensioning and shearing the 
wrapping 14, and possibly a portion of the shell 16, between the cutting 
portion 28 of the side plate 18 and the teeth 66 of the blade 24. The 
"saw" mechanism involves the removal of cast material by continually 
removing material from the shell 16 with the teeth 66, and the "shear" 
mechanism involves tensioning the wrapping 14 between the cutting portion 
28 of the side plate 18 and the teeth 66 of the cutting blade so that 
either the cutting portion 28 or the teeth 66 sever the wrapping 14. As 
used herein, "sliding scissors-like engagement" refers to the sliding 
engagement between the teeth 66 of the cutting blade 24 and the cutting 
portion 28 of the side plate 18 that facilitates shearing the soft 
wrapping 14. 
FIG. 6 illustrates a second embodiment of a cutting blade 124 of the 
invention wherein the plurality of elongate teeth 166 extend generally 
radially outwardly, and define a plurality of elongate slots 176, 178 
extending generally radially inwardly of the cutting blade 124. The slots 
176, 178 are adapted to receive a portion of the cast 12 to shear the cast 
12 between the teeth 166 and the cutting portion 28 of the side plate 18. 
Four of the slots 178 preferably extend radially inwardly farther than the 
other slots 176. For example, the longer slots 178 may have lengths that 
are approximately twice the lengths of the shorter slots 176. As is the 
case with cutting blade 24, the teeth 166 of the cutting blade 124 are 
tapered in the radially outward direction, and the cutting blade 124 
includes an enlarged annular hub portion 172. 
As illustrated in FIGS. 7 and 8, a cast separator generally designated 80 
may be mounted on the side plate 18 rearwardly of the notch 22. The 
separator 80 is adapted for spreading portions of the cast 12 that have 
been cut in order to facilitate advancing the assembly 10 and to prevent 
binding of the cutting blade 24 in the cast 12. The separator 80 may be 
removably mounted on a rearward portion of the side plate 18 by, for 
example, two "Allen" or hex head bolts or any other suitable means. The 
separator 80 preferably includes an elongate rod portion 82 extending 
generally rearwardly from the side plate 18, and a guide member 84 mounted 
adjacent the rearward end of the rod portion 82. 
The guide member 84 has an outwardly-facing annular guide channel 86 for 
receiving the portions of the cast 12 that have been cut. As shown in FIG. 
8, the guide channel 86 is positioned along a common plane with the 
longitudinal axis of the arcuate channel 60 and notch 22 of the side plate 
18. Alternatively, two outwardly-facing guide channels (not shown) may be 
provided. Such guide channels would preferably form a wedge shaped 
structure having an angle of divergence substantially equal to the angle 
A-2 of the taper of the arcuate channel 60. 
In operation, the assembly 10 is used to cut through the cast 12 as 
illustrated in FIG. 3. A portion of the cast 12 is introduced into the 
notch 22 of the side plate 18 and into contact with the teeth 66 or 166 
cutting blade 24 or 124, with the finger 34 of the side plate 18 
separating the cutting blade 24 from the patient 40. The cutting blade 24 
or 124 is then rotated relative to the cutting portion 28 of the side 
plate 18 by manually reciprocating the crank arm 26, while traction is 
manually maintained on the handle 64 as illustrated by the arrow 88 in 
FIG. 1 to advance the assembly 10 forwardly through the cast 12 as the 
cutting blade 24 or 124 is shearing the cast 12. After the cast 12 has 
been cut, it may be removed from the patient 40. 
The cutting blade 24 or 124 is preferably rotated in the direction wherein 
the teeth 66 or 166 move across the notch 22 in the direction toward the 
cutting portion 28 of the finger 34. The cutting blade 24 or 124 may 
conveniently (1) cut the rigid shell 16 by removing material therefrom 
with its teeth 66 or 166 in the manner of a saw blade, (2) grab and 
tension the wrapping 14, and possibly a portion of the shell 12, with its 
teeth 66 or 166 against the cutting portion 28 of the side plate 18, and 
(3) shear or slit the wrapping 14 and the tensioned portion of the shell 
12 between the cutting blade 24 or 124 and the cutting portion 28 of the 
side plate 18 in the manner of a pair of scissors. 
It will be observed that the illustrated assembly 10 is adapted for right 
handed operation, with the operator's left hand maintaining traction on 
the handle 64 while the right hand operates the crank arm 26. Of course, 
the assembly 10 could be readily adapted for left handed operation by 
reversing the positions of the handle 64 and crank arm 26 so that the 
operator's right hand maintains traction on the handle while the left hand 
operates the crank arm. 
In addition, the cutting blade 24 or 124 could be repositioned along the 
"left" side of the side plate 18 so that the crank arm 26 and cutting 
blade 24 or 124 are along the same side of the side plate. 
It is particularly contemplated that a blade guard (not shown) could be 
mounted or formed on the side plate 18 to cover the teeth 66, 166 of the 
cutting blade 24, 124. For example, an arcuate or crescent-shaped guard 
could be formed along the body 36 of side plate 18 with the open portion 
of the crescent being positioned adjacent the notch 22 of the side plate 
so that the teeth 66, 166 are only exposed in the notch 22. 
As various changes could be made in the above constructions and methods 
without departing from the scope of the invention, it is intended tha all 
matter contained in the above description or shown in the drawing shall be 
interpreted as illustrative and not in a limiting sense. 5:1.12