wire, etc.
Resistance is an obstruction in the electric circuit retarding the
flow of current.
Series connection means that two or more units are connected in line
with each other. Current enters one terminal, passes through the
windings, out of the other terminal, and directly into the next unit,
through its windings, and out to the opposite side of the line.
Parallel or multiple connection means that two or more units are
wired in such a way that each makes a complete circuit of themselves.
Current enters a unit, passing through its windings, and directly
back to the line.
Shunt—A conductor joining two points in a circuit and designed to
divert part of the current.
An electrical circuit carrying current can best be simply explained
by considering an iron pipe through which water is flowing under
pressure. The pipe represents the circuit, and water passing through
it represents the current. The volume of water flowing represents the
amperes, and the pressure of the water represents the volts. A leak
which allows the water to escape represents a short circuit, and a
valve in the pipe partially closed represents resistance.
ELECTRIC POT
The electrical equipment consists of four heaters, a dynamic
thermometer, and a unit control panel. The passage of electric
current through the windings inside the heaters generates heat which
melts the metal in the crucible and raises it to the proper operating
temperature, while the dynamic thermometer and the magnetic switch
on the control panel operate to keep the metal at this predetermined
temperature. These equipments are either 110 to 120 volts or 210 to
220 volts, direct current or alternating current.
The crucible heaters are the same for all voltages; they are
connected in “series” for 200-volt to 250-volt circuits and in
“parallel” for 100-volt to 125-volt circuits. They are immersed
directly in the metal and partially surround the pump-well, heating
the metal by direct contact. The heating element or resistor of these
heaters is composed of resistant ribbon wound on strips of clear
mica. Strips of mica entirely surround the resistor, completely
insulating it from the metal parts of the pot. The resistors are
protected by strong metal casings which surround them. They are not
subject to wear and tear in normal service.
Heating the metal by direct contact from within the metal itself by
these heaters, makes a very efficient equipment, as all of the heat
generated is immediately transmitted to the metal exactly where it
is required, and there is no loss of heat due to faulty conduction.
The dynamic thermometer bulb being immersed in the metal adjacent to
the heaters and the pump-well, permits of a very close temperature
regulation.
As these heaters extend nearly the full height of the metal in the
crucible and pass down through the top of the metal, there is no
possibility of cracking a crucible. When the metal begins to heat,
it is that portion in direct contact with the heaters which first
becomes molten. Internal pressure is relieved by this melted pathway
and the molten metal will flow to the top of the pot.
It is important that the pot never be filled with metal above the
under side of the ring which is cast on the inside of the crucible.
If the crucible is filled above this ring, metal may splash over into
the heating insulating material and touch the electric terminals,
grounding them.
The crucible heater must be entirely covered with metal at all times.
If they are not, that portion that is exposed to the air will get
very hot and continued exposure will burn them out, destroying them.
They are not designed for operation in the air.
Do not pry around the units with a screwdriver or pound on them, if
the metal envelope is punctured, molten metal will immediately enter,
grounding the element and destroying the unit.
The temperature in the crucible is controlled by an adjustable
dynamic thermometer mounted on the side of the pot, and which
operates a switch in the control panel, turning the current on and
off as needed. The bulb and tube of this thermometer contain mercury
and the bulb is immersed in the metal in front of the well of the
crucible. The tube is connected to a flattened hollow coiled spring
tube. The mercury also passes through this air tight spring tube.
On the free end of this coiled spring tube is fastened an insulated
pin which operates the contact lever. The contact lever is suspended
downward between two metal contact disks. These contact disks and
the contact lever are connected to the main line through a magnetic
switch mounted in the control panel. The thermometer only carries
current long enough for the magnetic switch to connect and then the
current is carried directly through the switch.
As the temperature of the metal rises the mercury in the bulb
expands causing the coiled spring to uncoil slightly, driving the
contact lever against the disk that shuts off the current, allowing
the switch to fall open and disconnecting the circuit through the
crucible heaters.
As the temperature of the metal falls, the mercury in the bulb
contracts allowing the coiled spring to force the contact lever
against the disk that turns the current on by connecting the switch
to the main line. The variation in the temperature is held within 15
degrees of the average working temperature.
The temperature control is normally set for a maximum of 550 degrees
and a minimum of 535 degrees, that is, with normal operation the
temperature of the metal will always be between these limits. This
is found to give the best all around casting results for average
metal. In case it is desired at any time to change the operating
temperature, this can be done by turning adjusting screw right-handed
for hotter metal, and left-handed for cooler metal. The head of this
adjusting screw projects through the right-hand side of the dynamic
thermometer cover.
Do not change the position of the control disks, unless badly pitted,
as their relative distance is determined at the factory, and very
seldom need to be changed.
A good thermometer should always be used when adjusting the screw for
proper heat. Guessing will not get the proper results.
With ordinary work, and after the metal is at operating temperature,
the current will be on and the crucible heaters generating heat about
three minutes, then off and not generating heat about twelve minutes,
and will repeat this cycle as long as snap switch is left in the “on”
position.
THROAT AND MOUTHPIECE HEATERS
The mouth and throat heaters are clamped in close contact with the
outside of the crucible throat to keep the metal at the operating
temperature while being pumped from the crucible to the mold. The
throat heater extends the full length of the pot throat and is held
in close contact with it. The mouth heater is clamped tightly to the
pot mouth. Both heaters are surrounded with heat insulating material
and are held in close contact with the pot throat and mouth by a
U-shaped clamp under the throat unit and a plate over the mouth unit,
drawn tight by two nuts.
The mouth and throat heaters are always connected in “series,” one
set being used for 100-volt to 125-volt and another set for 200-volt
to 250-volt.
The heat for the throat and mouth units are controlled by a manually
controlled rheostat moving from the left to the right, and fastened
to the front of the control panel under and at the rear of the
keyboard.
The rheostat is connected directly to the mouth and throat heater and
is not controlled by the dynamic thermometer.
The crucible heaters are intended for heating the metal to the proper
temperature, and the mouth and throat heaters are only intended to
keep the metal at the proper temperature while being forced from the
crucible to the mold.
If the voltage is irregular and remains too high for some time, or
a speedy operator casts large slugs at a rapid rate continuously,
the mouthpiece is apt to become heated and the slugs will have
hollow backs. In this case it will be necessary to turn rheostat
knob left-handed, but if the voltage remains low for some length of
time, or a slow operator casts small slugs slowly, the mouthpiece may
become cold and the slugs will have poor faces, in which case the
rheostat knob should be turned right-handed.
When casting large slugs in rapid succession the mold is apt to
become heated, but attempting to regulate the temperature of the
metal in the crucible to overcome the heating of the mold will fail,
because the electric pot is a heating unit only and will not cool the
mold.
The control panel consists of a magnet switch mounted on a slate
panel enclosed in a steel cabinet. The cabinet also has a suitable
fuse cut-out and the switches which control both the pot and the
electric motor (if used) and places all controls within easy reach of
the operator. Connection is made between the pot proper, the dynamic
thermometer, and the control panel by suitable wiring enclosed in a
flexible conduit.
CARE OF ELECTRIC METAL POT
The contact points on the thermometer and the magnetic switch should
be kept clean and free from corrosion. Use No. 00 sand-paper. (Never
use emery cloth or paper.) Dirt and corrosion are electrical
insulators, and if these contacts become dirty, electrical contact
may not be made when the temperature reaches 550 degrees F.; the
magnetic switch will not open and the crucible heaters will continue
to increase the temperature of the metal until the fuses are blown;
the dynamic thermometer permanently injured, or the heating units
burned out. When the temperature reaches above 550 degrees, the metal
is too hot, causing back squirts. When the metal has cooled, the
contacts, owing to the dirt, will not operate, and the metal will
continue to cool until it can not be used. The contact points should
be cleaned about once each two weeks.
The hole in the hollow tube connecting the bulb and the flattened
coil spring of the dynamic thermometer is very small and care must
be taken that the tube is not injured when feeding metal to the pot,
or that no sharp bends are made in it, as it will close the hole and
interfere with the proper working of the thermometer.
Occasionally some of the parts such as the heaters, thermometer, or
the wiring inside the pot may become damaged and will have to be
replaced. In ordering the new parts for replacements, be sure to
specify the voltage being used and the serial number of the pot. This
number plate can be found on top of the pot cover.
It is seldom that both crucible heaters will be burned out at the
same time, so if your pot is a 100 to 125-volt equipment, and one of
the crucible heaters tests open or grounded, and must be removed and
replaced, the metal in the crucible may be heated by the crucible
heater that is in good condition; but if your pot is 200 to 250-volt
equipment, and one of the crucible heaters must be replaced, it will
be necessary to melt the metal in the crucible with a blow torch
before either crucible heater can be removed. It is not necessary to
remove the metal from the pot. Merely keep the metal agitated while
melting it with the blow torch.
Frequently a heating unit is burned out by a little metal splashing
on the terminals, causing a gradual short circuit. This trouble can
be eliminated by wrapping the heater terminals with asbestos tape.
When cleaning the contact points on the dynamic thermometer, it is
necessary to remove the cover by taking out the two long flat head
screws. This cover should be examined for small particles of metal
before replacing.
To remove and replace a damaged wire in the pot, fasten another wire
securely to one end of it, grasp the other end with a pair of pliers
and pull. The new wire will be pulled in as the old one is removed.
Rubber covered wire or slow burning wire is not satisfactory. A
special wire with a special grade of insulation should be used.
If it becomes necessary to remove the dynamic thermometer, heat the
metal in the crucible to operating temperature and then turn the
main switch off. Disconnect the thermometer wiring and dip out the
metal to below the level of the thermometer bulb. Take off the pot
cover and remove the two screws fastening the thermometer case to
the bracket. Grasp the case with the hand and the bulb with a pair
of pliers and raise up and out. Be very careful at all times not to
damage or break the bulb or hollow wire which contain the mercury; to
do so will cause trouble in regulating the heat.
Replace the thermometer while the crucible is hot. See that the
bulb does not project out from the casting so as to interfere with
the insertion of ingots of cold metal. Press the tube firmly but
carefully into place over the edge of the crucible, being careful not
to injure it. Fasten the case to the bracket and reconnect the wiring
and put on the cover.
All the pot adjustments on the electric pot are the same as on a gas
pot.
CURRENT CONSUMPTION
The maximum current consumption is 1,500 watts and the minimum
325 watts, the average consumption throughout a day’s work is
approximately 600 watts or .6 kilo-watts. The cost of current
varies widely in different localities, but you may find the cost of
operating your pot by multiplying the number of hours by the cost
of current per kilowatt hour and then by .6. The result will be
the cost in cents. For instance, operating a pot nine hours with
current costing six cents per kilowatt hour would cost thirty-two and
four-tenths cents—9 x 6 x .6 equals 32.4 cents.
FUSES
The main line fuses, which protect the entire system from overloads,
when blown, should be replaced by other fuses of the same rating.
The fuse for the mouth and throat heater circuit is for the purpose
of protecting this circuit from accidents, and should always be
replaced by another fuse of the same rating. This replacing of the
fuses by others of the same rating is very important. On a 200 to
250-volt circuit, the main line fuses should be 10 amperes. The
mouth and throat fuse, which is located in the control box above the
magnetic switch, should be 3 amperes. On a 100 to 125-volt circuit
the main line fuses should be 20 amperes. The throat and mouth fuse
should be 5 amperes. Fuses of a greater amperage than those mentioned
may cause the units to burn out or cause a fire hazard.
MOLDS
The various models of machines placed on the market today have a
flexibility that requires a variety of molds to take care of the
varying lengths and thicknesses of slugs. The molds are adjustable
and are all removable from the mold disk should the occasion require.
The molds are all constructed along the same general line, with a
base and movable cap. The caps in all molds are held in place by two
guides, pinned on each end of the base of the mold, and projecting
into grooves in the cap.
The base of the mold is screwed firmly to the disk, and the two
liners are held in place by the cap and the pressure from three
screws which project through the rim of the mold disk. The cap and
base being held parallel by the guides.
To change the mold from one size of body or length of slug it is only
necessary to loosen the three screws, remove the liners and insert
the ones desired. Do not pry the cap upward with a screwdriver
inserted in the casting range of the mold cell. When tightening the
screws in the rim of the disk, bring them just to a firm bearing.
There is danger of cracking the rim if the screws are too tight.
THE UNIVERSAL ADJUSTABLE
The universal adjustable mold is the one most generally used. By
removing the liners and substituting others, slugs of any length
from 5 to 30 picas and from 5 to 14 points in body may be cast. All
standard molds will cast 30-pica slugs.
The right-hand, or constant liner, is marked for thickness only. It
is not necessary to change this liner unless the slug thickness is
changed.
The left-hand liner is marked for thickness and length. The number
stamped for the length, subtracted from 30, gives the length of
slug which will be cast. For example, if a 13-em slug is wanted,
use liner number 17, which allows the opening in the mold to be the
required length. When ordering liners for these molds, always specify
thickness and length of slug to be cast; also specify U. A. mold.
THE RECESSED
In order to cast light-weight slugs and for quick cooling, the
recessed mold is made. This mold will cast slugs with cavities,
or recesses. The base of this mold is the same as the universal
adjustable. The lower surface of the cap has rectangular projections
and grooves. The molten metal is forced into these grooves and forms
the supporting ribs beneath the type face. The rectangles form the
recesses. The weight of the slug is reduced about one-third. A more
solid slug is formed because there is less air to be displaced from
the mold. There is less metal in the mold cell, therefore it cools
more rapidly than the regular universal adjustable. These molds
require special left-hand liners and are adjustable for body size
from 10- to 14-point and all measures from 8 to 30 picas, except the
half-em measures. For these restricted measures a special mold is
required and will only be made on special order. In ordering liners
for a recessed mold you must be careful to specify “recessed mold”
and the length in ems required. These molds can be applied to any
model of machine, but must never be used for any size below 10-point.
DISPLAY AND HEADLETTER
The special display and headletter mold is similar to a recessed
mold, but to accommodate the increased size of faces, the recesses
are deeper. This mold has practically the same restrictions as to
length of slug as the recessed mold. One-letter matrices with the
character for raised position must be used on this mold. The filling
piece under the first elevator jaws must be used when using the mold.
Matrices can not be sent in on the duplex rails of the assembling
elevator.
Each display mold has a body range of 5 points only, so the entire
range of bodies from 15 to 36 points would require four of these
molds as follows: The range of one is 15 to 19 points, that is, any
width of liner from 15 to 19 points can be used on this mold; the
range of the second would be 20 to 24 points, the third would be 26
to 30 points, the fourth, 32 to 36 points. The range of the molds are
always marked on the cap so no mistake can be made.
In ordering liners for the display and headletter molds, care must be
taken to specify the range marked on the cap.
These molds are limited as to length of measure the same as the
recessed molds.
ADVERTISING
The advertising figure mold differs from the universal adjustable
only in the mold cap. The cap is constructed with an extra thick lip
against which the overhang in the matrices are cast. This permits of
casting large characters, which will lap over one or more adjacent
slugs. The grooves in the cap are ground parallel. With this mold
slugs from 5- to 12-point can be cast, but not above 12-point at any
time. This mold can also be used for casting headletter type, by
letting the letter overhang the slug. Place a blank slug underneath
the overhanging letters to support them.
When using the advertising figure equipment, display figures or
characters can be cast at any desired point in the line of text
matter, the characters or figures casting on the first slug against
the lip of the mold, thus overhanging one or more other slugs when
assembled.
In determining how large a figure may be cast on any size of slug
from 5- to 12-point, bear in mind that not over eleven points of the
figure may be cast against the lip of the mold cap.
CARBOLITE
There is an adjustable mold used on some machines which is made of
carbolite steel. This mold is harder than the regular U. A. mold and
will not warp easily. However, it heats up quicker, retains the heat
longer and will not work very satisfactorily for large slugs or where
a large amount of metal is used. The regular U. A. liners are used on
this mold.
36-EM ADJUSTABLE
The universal adjustable molds for 36-em machines will cast any
measure from 30- to 36-ems inclusive, from 5- to 14-point body. If a
measure shorter than 30 ems is desired a regular 30-em mold must be
used.
In order to change liners on a 36-em mold it is necessary to take the
mold from the mold disk, as the liners fit around three sides of the
post, and can not be changed in the regular way.
It is possible to remove the 36-em mold from the disk and substitute
a 30-em mold. A filling piece is required to take up the difference
between the 30-em and the 36-em mold.
MOLD WIPERS
There are two felt wipers which are designed to keep the face and
back of the mold clean. A small amount of a mixture of cup grease and
graphite rubbed into the back wiper will keep the base of the mold
clean. For the front mold wiper, keep the felt well saturated with
graphite. Do not use oil or grease on the front wiper, or it will be
transferred onto the matrices and into the magazine. A good plan is
to soak the felt with gasoline and rub the graphite in. When the felt
becomes worn, new ones should be applied. When applying new felt,
put graphite between the layers. Be careful that the felt does not
become worn to the extent that the steel part of the wipers will be
allowed to rub against the mold.
MOLD HINTS
If the mold cap guides become bent they will throw the mold cap
out of alignment with the constant side of the mold. The guides
can be straightened by removing the mold from the disk. Place a
straight-edge across the mold and cap to determine how the guides are
bent. They may be tapped with a hammer and a piece of brass rule to
spring them back in position. Care should be used in this operation
and if bent very much, the mold should be shipped to the nearest
agency for repairs. A mold with bent guides or a warped cap will
cause back squirts and to remedy these, the mold must be repaired.
Mold cap guides can be renewed by driving out the small pin that
holds them in place in the base of the mold and fitting in new ones.
If a mold has become warped by overheating, it can be shipped to
the nearest agency to be ground. If the mold is ground on the back,
the slug will be less than type high, according to the amount taken
off in the grinding. The liners must be ground as well as the mold.
Always be very careful of the mold so this will not be necessary.
The bottom of the mold sometimes becomes tinned. This will not
permit the mold and mouthpiece to lock up properly. The trouble can
be remedied by removing the mold from the disk and placing it on
the bench. Put a small amount of metal polish on a block of hard
wood. Rub the wood back and forth the entire length of the bottom
of the mold, with an even pressure. As the metal polish contains an
abrasive, the mold, cap, and liners should be kept together, so that
the casting edge of the mold will not be rounded. Be careful of the
molds as they are one of the most important parts of the machine and
will run indefinitely if handled intelligently.
Take the mold apart and clean the base and the cap with the polish.
Place each part in a vise so it will be held solid while cleaning.
After using the polish, clean with gasoline.
When metal gets into a mold cap screw in the disk after a squirt, do
not hammer the metal with a screwdriver. To do so merely drives the
metal tighter in the threads of the hole. Gouge the metal out with a
knife a little at a time.
Do not remove the mold keeper from the mold. The mold keeper is for
the purpose of holding the lugs of the matrices in alignment. If it
is removed and not replaced properly, it will interfere with the
proper alignment of every line set.
Keep the face of the mold clean and free from metal which has a
tendency to accumulate during the day while the mold is being used. A
clean face of the mold will greatly facilitate the press make-ready.
Metal on the mold causes high and low letters on the slug.
REMOVING AND REPLACING MOLD
To remove a mold from the disk, loosen the three screws in the rim of
the disk, take out the four screws which hold the mold to the disk
and lift the mold out of the pocket, being very careful not to drop
it.