Convertible sprocket for motion picture film

A convertible sprocket for film and like media accommodates different media formats. The sprocket includes a first sprocket wheel support and a first sprocket wheel having a first dimension and supported by the sprocket wheel support. A second sprocket wheel support is co-axial with the first sprocket wheel support. A second sprocket wheel having a second dimension different from the first dimension is supported by the second sprocket wheel support. The second sprocket wheel is axially movable relative to the first sprocket wheel support so that the first sprocket wheel engages the medium when the second sprocket wheel is in a first position relative to the first sprocket support. The second sprocket wheel engages the medium when the second sprocket wheel is in a second position relative to the first sprocket support. The convertible sprocket has a plurality of axially spaced apart sprocket wheel wherein at least two of the sprocket wheels have different diameters.

BACKGROUND OF THE INVENTION 
1. Field of The Invention 
The present invention relates to convertible sprockets for film and other 
media for accomodating different media formats, and more specifically to a 
convertible sprocket which can accommodate more than one format, such as 
more than one frame pitch for the medium. 
2. Related Art 
Conventional 35 mm film cameras and projectors operate with 35 mm film 
having a film frame pitch of four perforations per frame. The film is 
transported at a rate of 24 frames per second and 90 feet per minute. Film 
recording and projection equipment have long been standardized to operate 
with the four perforation frame pitch for 35 mm film. Therefore, equipment 
such as projectors use sprockets and pull-down assemblies specifically 
designed to operate with 35 mm film having four perforation frame pitch. 
The sprockets for conventional 35 mm film have 16 teeth around the 
circumferential surfaces. The frame pitch is 0.748 inches and the 
corresponding sprocket diameter for a 16 tooth sprocket is 0.952 inches. 
Efforts have been made recently to more efficiently use available film 
stock by putting more film frames in a given unit length of film stock. 
One proposal has been to convert from a 4 perforation film frame pitch to 
a 3 perforation film frame pitch to eliminate 25 percent of unused film 
stock. Other film frame pitches and formats have also been proposed. To 
accommodate these different film formats and still project the film at a 
frame rate of 24 frames per second, according to the North American 
Standard, the projection and other film handling equipment must be 
modified to accommodate the changed format. It is believed that more than 
one frame pitch for motion picture equipment will be adopted by the film 
industry. While the standard Edison frame pitch of 4 perforations will 
remain useful, other intermittent pull-down pitches will be used to meet 
specific needs, such as presentation quality, economy, or efficiency. For 
example, possible additional film formats may require picture frames 
having perforation pitches of 5 perforations, 3 perforations, 21/2 or 2 
perforations. However, changing from one film format to another for a 
given piece of equipment such as a projector is a time consuming and 
tedious process. Moreover, once a given piece of equipment is converted, 
the previous 4 perforation frame pitch can no longer be used with the 
equipment unless the sprocket assemblies and other components are 
reconverted. Conversion back and forth between the standard 4 perforation 
frame pitch and any modification will be necessary if more than one film 
format is to be accommodated in a projector or other piece of equipment. 
According to one approach, sprockets and other components of a projector 
or other piece of equipment for a given film format can be maintained on 
hand so that the projector can be converted at will. However, the 
conversion is a time consuming process, to be accomplished by film 
projectionists who would have to be trained to accomplish the conversion. 
Additionally, maintaining a complete set of conversion components may 
prove difficult because of possible loss or damage during the conversion 
process or while the equipment is being stored. 
In an alternative approach, a sprocket conversion assembly may be used 
which has an outer cylindrical sleeve with teeth for engaging film 
perforations when the film is run according to one format and an inner 
cylindrical sleeve to fit within and anti-rotationally mate with the outer 
cylindrical sleeve. The inner sleeve has teeth for engaging film 
perforations according to an alternative format. Such an arrangement may 
permit less time consuming and costly conversions from one film format to 
another. However, separate parts are still required and the outer sleeve 
may be lost or damaged when not in use. Additionally, engagement of the 
tines on the inner sleeve with mating grooves on the inside of the outer 
sleeve may wear the tines of the inner sleeve, which may adversely effect 
film transport when using the inner sleeve. 
There is a need, therefore, for a convertible sprocket which can be used to 
convert a given piece of equipment from one film format to one or more 
other film formats. Preferably, such a convertible sprocket is a single 
component which can accommodate the two or more film formats without 
having to store or remove additional equipment. the convertible sprocket 
is preferably easy to use and easily retrofit onto current equipment. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, a convertible sprocket is 
provided which can convert a given piece of equipment back and forth from 
one film format to one or more other film formats conveniently and 
quickly. The convertible sprocket of the present invention is easy to 
install and use, and does not require special training for use on 
conventional equipment such as projectors and the like. In accordance 
therewith, a convertible sprocket includes a first sprocket wheel having a 
first dimension supported by a first sprocket wheel support and a second 
sprocket wheel having a second dimension different from the first 
dimension supported by a second sprocket wheel support wherein the second 
sprocket wheel is axially movable relative to the first sprocket wheel 
support. Preferably, the first sprocket wheel engages the film or other 
medium when the second sprocket wheel is in a first position relative to 
the first sprocket support and the second sprocket wheel engages the 
medium when the second sprocket wheel is in a second position relative to 
the first sprocket support. 
With the convertible sprocket of the present invention, a single assembly 
can accommodate two or more film formats without having to replace or 
exchange equipment. With the convertible sprocket of the preferred 
embodiment, up to three film formats can be accommodated. Portions of the 
convertible sprocket need not be exchanged, removed or otherwise stored 
apart from the rest of the assembly, and thereby subject to loss or 
damage. 
In a preferred embodiment, the convertible sprocket includes detents for 
releasably fixing the second sprocket wheel relative to the first sprocket 
wheel support. In one embodiment, one or more detents are provided for 
releasably holding the second sprocket wheel fixed relative to the first 
sprocket wheel support so that the first sprocket wheel engages a medium 
and so that the second sprocket wheel is held out of engagement with the 
medium. In a second configuration, the detent releasably holds the second 
sprocket wheel relative to the first sprocket wheel support, after 
movement relative to the first sprocket wheel support so that the second 
sprocket wheel can engage a medium of a format different from the first 
medium and so that the first sprocket wheel is held out of engagement with 
the medium of the second format. In one specific embodiment, the first 
sprocket wheel is provided with a matching sprocket wheel of the same 
dimensions, such as for 35 mm film, and includes ten teeth for engaging 
film having a film frame pitch of 2.5 perforations per frame. The second 
sprocket wheel may also include an additional matching sprocket wheel 
having dimensions the same as the corresponding second wheel with 16 teeth 
to accommodate 35 mm film having a standard film frame pitch of 4 
perforations per frame. In another preferred embodiment, a third pair of 
matched sprocket wheels having diameters greater than the diameters of the 
first and second sprocket wheel pairs are dimensioned and have 20 teeth 
for accommodating 70 mm film. 
In an alternative embodiment, a convertible sprocket is provided for 
accommodating different media formats having a plurality of axially spaced 
apart sprocket wheels wherein at least two of the sprocket wheels have 
different diameters. In the preferred configuration, the sprocket wheels 
are axially movable relative to each other to position different ones of 
the sprocket wheels to separately engage respective media according to the 
particular format of the medium. 
In accordance with the foregoing, it is a principal object of the present 
invention to provide a convertible sprocket in a single assembly. 
It is a further object of the present invention to provide a convertible 
sprocket which is easy to use and requires no special skills to install, 
retrofit or operate. 
It is an other object of the present invention to provide a convertible 
sprocket assembly which does not require removal of disassembly of any 
parts to convert from one film format to another. 
It is another object of the present invention to provide a convertible 
sprocket which reduces any excessive film or equipment wear during use. 
It is a further object of the present invention to provide a convertible 
sprocket which can accommodate two or more film formats, such as for 
picture frames whose heights correspond to 5 perforations, 4 perforations, 
3 perforations, 21/2 perforations or 2 perforations. 
These and other objects of the present invention will become apparent by 
consideration of the drawings, a brief description of which is provided 
below, as well as the detailed description of the preferred embodiments to 
follow.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
A convertible sprocket for film and like media is disclosed for 
accommodating different media formats and which is self-contained, easy to 
use and requires no special skills for installation, retrofitting or use, 
which requires no disassembly or removal of separate pieces for use or 
storage and which reduces excessive film or equipment wear during use or 
storage. In accordance with one aspect of the present invention, a first 
convertible sprocket assembly 20 (FIGS. 1 and 2) is shown for use in 
conjunction with a projector or other equipment (not shown) for handling 
film media such as the film strip 22. The film strip 22 may have one of 
any number of film formats, such as film formats having picture frames 
whose heights are 5 perforations, 4 perforations, 3 perforations, 21/2 
perforations, 2 perforations or 1 set of perforations. For example, 16 mm 
film uses 1 pair of perforations on each side of the film strip for each 
film frame. Conventional 35 mm film has a film frame pitch of 4 
perforations per frame. Other purposed formats include 35 mm film having 
film frame pitches of 3 perforations per frame. Combinations of up to 
three of these film formats can be accommodated using the convertible 
sprocket assembly of the present invention. FIGS. 1 and 2 show the 
sprocket assembly 20 which can accommodate three different film formats. 
In the preferred embodiment, a conventional sprocket support shaft 24 is 
modified to accommodate the movable sprockets according to the present 
invention. The shaft is made sufficiently long to accommodate both 35 mm 
formats and 70 mm film formats. The shaft 24 slidingly accepts a first 
sprocket wheel support or sleeve 26 co-axial with and axially slidable 
relative to the shaft 24. The first sprocket wheel sleeve 26 is 
rotationally fixed relative to the shaft 24 by a key 28 engaging 
corresponding key ways in the shaft 24 and in the corresponding sprocket 
wheel sleeve 26. A second sprocket wheel sleeve 30 is similarly mounted to 
the shaft 24 so that the second sprocket wheel sleeve is supported by and 
can move axially relative to the shaft and also relative to the first 
sprocket wheel sleeve 26. The second sprocket wheel sleeve 30 is 
rotationally fixed relative to the shaft by the key 28 engaging the 
corresponding key way in the second sleeve 30 in the shaft 24. The 
sprocket wheel supports are prevented from removal by a flange screw (not 
shown in FIGS. 1 and 2) discussed more fully below with respect to the 
embodiments of FIGS. 3-8. 
In the preferred embodiment, the convertible sprocket assembly includes one 
or more detent mechanisms for releasably retaining each sprocket wheel 
sleeve on the shaft in a given position so that a selected sprocket wheel 
or sprocket wheels can engage the film strip, while at the same time 
permitting repositioning of one or both of the sprocket wheel sleeves 
relative to the other so that a different sprocket wheel or sprocket 
wheels can be positioned to engage a film strip having a different film 
format. In the embodiment shown in FIGS. 1 and 2, the first sprocket wheel 
sleeve 26 includes a first sprocket wheel 32 having a first dimension or 
diameter for engaging the film strip 22. In the embodiment shown in FIGS. 
1 and 2, the first sprocket wheel 32 is a 10 tooth sprocket wheel for 
engaging film having a film frame pitch of 2.5 perforations per frame. The 
sprocket wheel has the dimensions shown in Table I. Additionally, the 
second sprocket wheel sleeve 30 includes an additional first sprocket 
wheel to match the first sprocket wheel 32 on the first sprocket wheel 
sleeve 26 for engaging the same film strip. 
The first sprocket wheel sleeve 26 includes a detent mechanism 36 for 
releasably maintaining the first sprocket wheel sleeve 26 and therefore 
the first sprocket wheel fixed relative to the shaft 24 and also relative 
to the second sprocket wheel sleeve 30. The shaft 24 includes a pit or 
other surface (not shown) for engaging the detent mechanism 36 and thereby 
retaining the first sprocket wheel 32 and its sleeve 26 axially fixed 
relative to the shaft 24. 
The second sprocket wheel sleeve 30 also includes a corresponding detent 
mechanism 38 for releasably retaining the second sprocket wheel sleeve 30 
fixed relative to the shaft 24. The shaft 24 includes a further pit or 
other surface for engaging the corresponding detent mechanism 38 to 
releasably fix the second sprocket wheel sleeve 30 relative to the shaft 
24. 
The shaft also preferably includes a first closure pit 40 on the shaft 
between the first and second pits, for the detent mechanisms 36 and 38, 
respectively, and colinear therewith. The first detent mechanism 36 
engages the first closure pit 40 when the first sprocket wheel sleeve 26 
is moved axially toward the second sprocket wheel support. Engagement by 
the first detent mechanism 36 with the first closure pit 40 axially fixes 
the first sprocket wheel sleeve 26 relative to the shaft 24 and also 
relative to the second sprocket wheel sleeve 30. The shaft further 
includes a second closure pit 42, between the pits corresponding to the 
detent mechanisms 36 and 38, for engagement by the second detent mechanism 
38 when the second sprocket wheel sleeve has moved inwardly toward the 
first sprocket wheel sleeve 26. Engagement by the second detent mechanism 
38 with the second closure pit 42 axially fixed the second sprocket wheel 
sleeve 30 relative to the first sprocket wheel sleeve 26. When the first 
and second sprocket wheel sleeves 26 and 30, respectively, have been moved 
inwardly toward each other, the sprocket wheel supports have the 
configuration shown in FIG. 2. The first and second detent mechanisms 36 
and 38, respectively, then engage the first and second closure pits 40 and 
42, respectively. The first open pit 44 is then unoccupied and the second 
open pit 46 is also unoccupied, in the preferred embodiment. 
Axially spaced apart from the first sprocket wheel 32 is a second sprocket 
wheel 48 supported by the second sprocket wheel sleeve and having a second 
dimension, namely its diameter, different from the first diameter of the 
first sprocket wheel 32. In the preferred embodiment, the second sprocket 
wheel 48 has dimensions corresponding to a sprocket wheel for engaging 
conventional 35 mm film having a frame pitch of 4 perforations per frame. 
The dimensions and characteristics for the second sprocket wheel 48 are 
shown in Table I. A matching second sprocket wheel 50 is mounted to the 
first sprocket wheel sleeve 26 spaced apart from the matching first 
sprocket wheel 34 and also spaced apart from the second sprocket wheel 
sleeve 30. The matching second sprocket wheel 50 has the identical 
dimensions and characteristics as the second sprocket wheel 48. In the 
preferred embodiment shown in FIGS. 1 and 2, the second sprocket wheels 48 
and 50 are spaced from their respective adjacent first sprocket wheels 34 
and 32, by a distance corresponding to one-half the distance separating 
the opposing faces 52 and 54 on the sprocket wheel sleeves 30 and 26, 
respectively. In this configuration, movement of both the first and second 
sprocket wheel sleeves 26 and 30, respectively, axially toward each other 
so that the corresponding detent mechanisms 36 and 38 engage their 
corresponding closure pits 40 and 42, respectively, aligns the second 
sprocket wheels 48 and 50 with the perforations in 35 mm film so that the 
second sprocket wheels can engage and drive conventional 35 mm film having 
a film frame pitch of 4 perforations per frame. In this configuration, the 
convertible sprocket assembly can accomodate 35 mm film having two 
different film frame pitches, namely 2.5 perforations per frame with the 
first sprocket wheels 32 and 34 and 4 perforations per frame with the 
second sprocket wheels 48 and 50. Other film formats can be accommodated 
simply by using different sprocket wheel dimensions and configurations. 
Additional sprocket wheels for other 35 mm formats may be accommodated by 
suitable placement of detent mechanisms and retaining surfaces therefor. 
An additional pair of sprocket wheels 56 and 58 are mounted on respective 
sprocket wheel sleeves 26 and 30, respectively, and spaced relative to 
their adjacent sprocket wheels 50 and 48 such that when the first and 
second sprocket wheel sleeves 26 and 30 are moved toward each other to be 
adjacent. The distance between the sprocket wheels 56 and 58, when moved 
together, are such as to accommodate 70 mm film having 5 perforations per 
film frame. In this configuration, the convertible sprocket assembly can 
accommodate at least three different film formats. A 5 perforation pitch 
may be useful in anamorphic formats. 
In the configuration of the sprocket assembly 20 shown in FIG. 1, the 
second sprocket wheel 48 is axially movable relative to the first sprocket 
wheel sleeve 26 so that the first sprocket wheel 32 engages the film 22 
when the second sprocket wheel is in a first position, shown in FIG. 1, 
relative to the first sleeve 26. The second sprocket wheel 48 engages film 
having a different film format from that accommodated by the first 
sprocket wheel 32 when the second sprocket wheel 48 is in a second 
position, shown in FIG. 2, relative to the first sleeve 26. While the 
convertible sprocket 20 shown in FIGS. 1 and 2 includes matching sprocket 
wheels for the first sprocket wheel 32 and for the second sprocket wheel 
48, it should be understood that matching sprocket wheels may not be 
necessary. 
In a further embodiment of the convertible sprocket assembly of the present 
invention, a convertible sprocket assembly 60 (FIGS. 3-8) is configured to 
accommodate operation with two or more film formats. The convertible 
sprocket assembly 60 includes a sprocket drive shaft 64 for supporting a 
first sprocket wheel support or sprocket wheel sleeve 66 for supporting a 
sprocket wheel 68 having a first diameter for engaging the film 62 using a 
first film format. In the specific embodiment considered herein, the first 
sprocket wheel 68 is sized and configured to include ten teeth for 
engaging film having a film frame pitch of 2.5 perforations per frame. A 
key 70 assures rotational alignment of the sleeve 66 with the shaft 64. 
The key 70 extends in a corresponding key way, one in the surface of the 
shaft 64 and another in the interior surface of the sleeve 66. The sleeve 
66 is axially fixed on the shaft 64 by a set screw 72. 
The sprocket wheel assembly includes a second sprocket wheel support or 
sleeve 74 axially slidable along the shaft but rotationally aligned with 
the shaft by the key 70 engaging corresponding key ways in the interior 
surface of the sleeve 74 and the external surface of the shaft 64. A 
matching sprocket wheel 76 has dimensions and a configuration identical to 
the first sprocket wheel 68 for engaging the film corresponding to the 
configuration of the first sprocket wheel 68. The matching sprocket wheel 
76 is positioned on the second sleeve 74 so that the sprockets 68 and 76 
engage the perforations on 35 mm film when the second sleeve 74 is spaced 
apart from the first sleeve 66 in the position shown in FIG. 3. 
A detent mechanism 76 releasably fixes the second sleeve 74 at its outboard 
axial position on the shaft 64 as shown in FIGS. 3 and 5. A second 
sprocket wheel 78 having a second diameter different from that of the 
first sprocket wheel 68 is supported by the second sleeve 74 for rotation 
with the shaft 64. The second sprocket wheel 78 is axially movable 
relative to the first sprocket sleeve 66 and the first sprocket wheel 68 
to the configuration of the sprocket wheel assembly shown in FIG. 7 where 
the facing surfaces of the sleeve 66 and 74 are substantially abutting. 
With the second sprocket wheel moved closer to the first sleeve 66, the 
second sprocket wheel 78 is positioned inboard to engage the perforations 
of a film strip 80 having a film format conforming to the configuration of 
the second sprocket wheel 78. For example, in the embodiment of the 
convertible sprocket assembly shown in FIGS. 3-8, the second sprocket 
wheel 78 is configured and dimensioned to accommodate standard 35 mm film 
having a frame pitch of 4 perforations per film frame. 
In the outboard configuration, where the second sprocket wheel is in the 
first position (FIG. 3) relative to the first sprocket sleeve, the first 
sprocket wheel 78 and the matching sprocket wheel 76 engage the film strip 
62 wherein the film strip 62 has a frame pitch of 2.5 perforations per 
frame. When the second sprocket wheel is axially moved inboard to the 
second position (FIG. 7), relative to the first sprocket wheel 66, the 
second sprocket wheel engages the film 80 to operate with the film 80 in 
the conventional matter. In this configuration, the convertible sprocket 
assembly has a plurality of axially spaced-apart sprocket wheels 68, 76 
and 78, wherein at least two of the sprocket wheels, namely 68 and 78, 
have different diameters for accommodating film of different formats. 
Considering the adjustment mechanism in more detail, with respect to FIGS. 
3 and 5-7, the shaft includes a first pit 82 (FIG. 7) for accommodating 
the detent mechanism 76 when the second sleeve 74 is in the outboard 
position. A second pit 84 (FIGS. 3 and 5) is located a distance inboard 
from the first pit 82 a distance corresponding to the distance between the 
matching sprocket wheel 76 and the second sprocket wheel 78. Therefore, 
when the second sleeve 74 is moved inboard relative to the first sprocket 
wheel sleeve 66, and the detent mechanism 76 engages the second pit 84, 
the second sprocket wheel 78 engages the new film 80, as shown in FIG. 7. 
In the preferred form of the invention, the detent mechanism includes a 
ball detent assembly 86 including a ball 88 received in a chamber 90 and 
biased outwardly by a spring 92 (FIG. 5). The chamber 90 is formed in the 
interior surface of the second sleeve 74. In the preferred embodiment, the 
detent mechanism includes two ball detent assemblies, in opposite sides of 
the interior surface of the second sleeve. Therefore, two sets of first 
and second pits 82 and 84 are included on the shaft 64. Other releasable 
axial retaining mechanisms can be used as would be apparent to those 
skilled in the art. 
A flange screw 94 is threaded into a correspondingly threaded outboard 
opening in the shaft 64 to axially retain the second sleeve 74 on the 
shaft during normal operation. Upon assembly of the convertible sprocket 
assembly, the flange screw 94 is removed and the second sleeve 74 along 
with the corresponding sprocket wheels and the detent mechanisms 86 are 
passed axially over the end of the shaft 64. The flange screw 94 is then 
threaded to the end of the shaft until the flange screw 94 is fully 
seated. The flange screw thereafter prevents removal of the second sleeve 
74. In the preferred embodiment, the base of a counterbore 96 is formed 
deep enough so that no rubbing or contact occurs between the head of the 
flange screw 94 and the surface of the second sleeve 74. 
It has been determined that the tooth-perforation film wrap of the 10-tooth 
sprocket mode is 3 perforations times two sprocket wheels, yielding an 
accumulated film wrap of 6 perforations for the embodiment shown in FIG. 
3. The 16-tooth single sprocket wheel mode shown in FIG. 7 yields a film 
wrap of 5 perforations. The 16-tooth sprocket wheel mode shown in FIG. 2 
would yield a film wrap of 10 perforations. Reliable film transport is 
achieved in either mode of operation. Additionally, use of polyester-base 
film is becoming more common and minimizes damage to film perforations. 
The accompanying Table I shows dimensions and characteristics for operation 
with convertible sprocket assemblies and their corresponding film formats. 
Column 1 headed Perforation Pitch identifies the perforation pitch for the 
given film transported and determines the particular sprocket arrangement 
used with the film. The columns headed Sprocket Diameter and Film Speed 
provide the dimensions and characteristics for film transport for the 
given perforation pitch, with the equipment operating to record, produce 
or otherwise accommodate a film rate of 24 frames per second. The column 
headed Sprocket Ratio To 4 Perforations indicates the ratio of sprocket 
teeth for a sprocket wheel accommodating the conventional 4 perforation 
frame pitch relative to a sprocket for accommodating film having a 
perforation pitch identified in the first column. The data in Table 1 
indicate the benefit being achieved through use of different film formats. 
Table II identifies preferred dimensions for the convertible sprocket 
assembly components as shown in FIG. 9. These dimensions are provided to 
correspond to the convertible sprocket assembly shown in FIGS. 3-8. Other 
dimensions for other configurations would be apparent to those skilled in 
the art. 
The described embodiments are not limited to specific frame pitches or to 
specific equipment such as motion picture cameras, editing machines, 
projectors or other film equipment. The described embodiments are also not 
limited to 35 mm or other configurations of motion picture film. Other 
media and equipment are possible. 
TABLE I 
______________________________________ 
Sprocket 
Perf. 
Frame Sprocket Film Ratio To 
Print Length/ 
Pitch 
Pitch Diameter Speed 4 Perf. 
111 minutes 
______________________________________ 
5 .935" 1.190" 112.5'/min. 
8:10 12,500' 
4 .748" .952" 90'/min. 8:8 10,000' 
3 .561" .714" 67.5'/min. 
8:6 7,500' 
2.5 .468" .595" 56.25'/min. 
8:5 6,250' 
2 .372" .476" 45'/min. 8:4 5,000' 
______________________________________ 
TABLE II 
______________________________________ 
DIMENSION 
DESCRIPTION IN INCHES 
______________________________________ 
a. film width 1.377 
b. shaft diameter .375 
c. sleeve diameter .455 
d. outboard width large sprocket wheel 
.106 
e. space between sprocket wheels 
.053 
f. inboard width small sprocket wheel 
.106 
g. outboard sleeve width .503 
h. inboard sleeve width .503 
i. inboard width large sprocket wheel 
.106 
j. large sprocket diameter 
.952 
k. small sprocket diameter 
.595 
l. film perforation .110 .times. .078 
m. sprocket tooth .065 .times. .055 .times. .050 
n. lateral shift part A .265 
______________________________________