Boxoffice_May.09.1960

BASIC REQUIREMENTS FOR
BETTER PROJECTION
A Review of Maintenance Procedures
I
To Keep Equipment in
Top Condition
This photo was selected from many because it
shows many important features that should be in
every first-class projection room. The equipment
is Constellation projection lamps and Philips Norelco
projectors, recently installed in the Shoppingtown
Theatre, Dewitt, N. Y., by National Theatre
Supply. The work light (I) has a long extension
cord on a reel so that it can be used any place in
the projection room. A large exhaust system (2) is
used to give adequate ventilation for these powerful
arcs. In the ceiling (3) is an adjustable light
so that it shines down on the mechanism. The
wiring (4) is concealed in the base and floor except
the asbestos wires to the arc. The projection
room floor (5) is covered with heavy battleship
linoleum. On the floor, near the front of the projector
base (6) is the foot switch for operating the
electric changeover. The large lens used in this
projector (7) is set on the ledge. The sound
changeover (8) is mounted on the front wall with
the other units. The lens and observation ports (9)
have glass in them to keep noise from the projectors
getting into the auditorium, and are set at
an angle to avoid glare. A very neat projection
room layout.
By
WESLEY TROUT
w.E HAVE WRITTEN REAMS Of papCl"
on new developments in sound and projection
equipment, plus instructions on
maintenance the past ten years. However,
we think it is a good idea, at this time, to
review again some of the basic requirements
necessary to keep your equipment in
good operating condition.
In many past articles, we have called to
your attention the importance of keeping
your equipment clean, and the importance
of using the correct type of lubricant. By
observing these rules, the life of your equipment—sound
and projection— will be prolonged
many years, and you will obtain
practically troublefree operation. This
.should be the goal of every theatre manager
and projectionist. Don't let your
equipment get into bad running condition
by not installing parts when they have
become badly worn. No equipment will
function 100 per cent if it is not properly
maintained and kept correctly adjusted.
The modern projector is a rather expensive
mechanism. It will give long serv-
ice if properly taken care of: in other
words, it must be kept clean, parts replaced
when they show appreciable wear,
and most important is using the right
type of lubricant for the geartrain, bearings
and intermittent movement. We
strongly recommend that you use only the
lubricant recommended by the manufacturer:
some types of oils and greases are
absolutely unfit for projectors. Their use.
we are firmly convinced, shorten the life
of a projector very greatly. A high quality
oil or grease, whichever the case may be,
is not expensive and will assure better
service and longer life of your projector.
Keep this in mind: The purpose of oil
or grease is to separate moving parts, and
thus reduce friction and wear to the least
possible minimum. Therefore, you can
readily understand the importance of using
high quality lubricant for moving parts
in a modern projector.
OILING THE
BEARINGS
Very important is the careful filling of
the oil reservoir or bearings. Never, under
any circumstances, use more oil than necessary
as excessive oiling runs all over
the mechanisms, down into the sound head
and on the floor, making a very nasty mess.
The "heart" of your projector mechanism
is the intermittent movement. It requires
special attention because the parts
run at a very high speed and if not carefully
adjusted, the movement will be noisy
and sometimes cause picture jump. Always
insist, if you have your movement
repaired at a shop, on installation of both
a new cam and starwheel. Never attempt
to install a new star and try to make it
run with an old cam, or visa versa. We
also recommend that new bearings be installed
at the same time, thereby assuring
a first-class job.
ADJUSTMENT OF
INTERMITTENT
While we are on the subject of intermittent
movements, when the intermittent
movement is on "lock" its adjustment
should be such that there will be very little
circumferential movement in the intermitten
sprocket, but care must be exercised
that the adjustment is not too close which
may cause the movement to lock up. Too
tight fit between the cam and starwheel
causes unnecessary friction and wear.
There should be just a little so that when
the parts heat up the slight expansion will
not cause friction. Remember, in the heat
of the spot, all parts expand more or less,
and that fact must be taken into consideration
when making final adjustments of
parts.
Close adjustment of parts can not be
made if the bearings are appreciably worn.
During our many inspection trips over
the territory, we have found projector
mechanisms with excessive gate tension.
Heavy tension is absolutely unnecessary
and wears down tension shoes and film
track shoes. The most simple instruction
we can give you on adjusting the tension
is this one: Use only enough tension to
hold the film steady on the screen when
projector is running 90 feet of film a minute.
This tension can be adjusted easily
on most projectors: on some of the old
models, bending of the tension springs may
have to be resorted to, and on modern
mechanisms, there is a screw for increasing
and decreasing tension.
VARIABLE SHOE TENSION
Some of the modern mechanisms have a
variable shoe tension setup and this can be
adjusted for old and new films. Set the
variable shoe tension indicator to the desired
point, "Low," "Std.," or "High." The
low position provides a film tension of
about 225 grams, suitable for new, green
film. The tension in the "Std." position is
approximately 373 grams, which is the
correct tension for film in average condition.
The "High" position increases the
tension to around 675 grams to aid in
flattening badly buckled or real old films.
Again, we want to remind you that excessive
tension should never be used, only
when necessary in order to avoid film
damage and unnecessary wear of parts.
Moreover, excessive tension will cause
rapid wearing of the intermittent sprocket
teeth and heavy pull on the cam and starwheel.
This should always be avoided.
LATERAL GUIDE ROLLER ASSEMBLY
Another unit sadly neglected, we have
found on our trips, is the lateral guide
roller assembly. Often these are not kept
rolling and this has caused grooves to
wear in the sides of the rollers, thereby
causing some side-weave of picture. These
rollers should turn freely on the shaft so
that grooves will not form and be kept
adjusted so that the film will travel in a
straight line down to the intermittent
sprocket.
The takeup should be carefully adjusted
so that there is no more tension on it than
necessary. Here again, excessive tension is
bad and will cause rapid wearing of the
takeup sprocket teeth: and excessive tension
can cause film damage— tearing out
of sprocket holes and noise. Moreover, always
replace the takeup sprocket when
teeth show appreciable wear. Keep sprocket
teeth free of dirt, and oil cleaned off of
takeup belt and takeup assembly. Use only
good house reels in the magazines.
In drive-in theatres, projector mechanisms
should be kept covered when not
in operation, even though there may be
glass in the ports. If no glass in ports.
Continued on page 24
22
The
MODERN THEATRE SECTION