METAL POT

The metal pot consists of the pot jacket and pot crucible. The jacket is the outside casting. The crucible fits into the jacket, allowing space between the crucible and jacket for asbestos packing. The crucible is held in place in the jacket by three lugs, which keep it stationary in the jacket. All the space between the crucible and jacket is packed tightly with powdered asbestos which has been mixed with a little water until a paste is formed. This insulation is for the purpose of holding the heat in the crucible.

It is very important that every pot should be well insulated or packed. If there is poor packing the crucible can not hold the heat. The result being poor slugs, and the consequent use of more gas than is necessary. If the machine takes an excessive gas flame to keep the metal in working condition, look for poor insulation.

The well of the pot, which contains the metal before it is forced through the mouthpiece by the plunger, must have sufficient metal under the plunger to form a perfect slug when a cast is made. For that reason two holes are drilled in the well, one on each side, which allows the metal to enter the well. If the holes become closed, which they sometimes do if the well is not cleaned regularly, the slug will be hollow. They should be kept open, using the end of the mouthpiece wiper, which is bent at a right angle and pointed. The metal pot has a capacity of 38 pounds of metal.

Metal Pot Plunger

The metal is forced by the plunger from the well, through the throat of the crucible, into the mold cell, and up against the line of matrices aligned in front of the mold.

When the machine is in normal position, the plunger should be high enough in the well to permit the metal to run into the well through the holes in the sides. If the plunger does not set above the holes, the metal can not flow into the well and throat, so when the line is cast the slug will appear porous or spongy and of light weight.

If a plunger is worn, it will permit the metal to escape around the sides of the plunger when the cast is made, giving a poor slug. To remedy this trouble it is sometimes necessary to put in a new plunger a trifle oversize (.005), and fit it to the well.

A dirty plunger may bind and cause a splash of metal to be ejected before the pot locks up tight and, chilling on the back of the mold, prevent a lockup, so the metal will flow out over the back of the disk when the plunger acts. A dirty plunger will often cause a slug to have the appearance of cold metal. Keep the plunger and the well of the pot clean.

Any kind of a wire brush may be used to clean a plunger, but the Ewald cleaning box is recommended, because it keeps all the dust confined in the box. There are several kinds of brushes and scrapers manufactured for use in cleaning the well. Use whatever method desired, but be sure it keeps the well clean.

If using a rotary well brush to clean the walls of the well, be sure to turn it always to the right, otherwise the bristles may break off and stay in the well.

If a plunger should stick in the well very tightly, raise the temperature a little, apply a wrench to the plunger rod and twist it carefully. Do not use too much force or the rod may be broken. If a plunger sticks so that it can not be removed by the above method, dip enough metal out of the crucible to expose the well; squirt some oil between the plunger and the inside wall of the well, or drop a piece of tallow in the well; let it stand for a few minutes, after which the plunger can usually be loosened with the wrench as described. Do not pry up on the plunger for there is danger of breaking the rod.

When the plunger forces the metal through the throat of the crucible, there will be nothing to retard the flow of metal against the face of the matrices if the throat of the crucible is clean. However, if the throat should be stopped up with dross or dirt, retarding the flow of metal, the face of the slug would be glassy, and have the appearance of cold metal.

Cleaning the Throat of Crucible

To eliminate a stoppage in the throat it is sometimes necessary to remove the mouthpiece and scrape out the throat, using a throat scraper to cut away the accumulation of dirt and dross.

The scraper sold by the Linotype Company is recommended for the purpose. Care must be used to get the throat clean. Hold a receptacle that does not leak up in front of the crucible mouth and force the plunger down by hand. This will flush the throat of any floating particles of dross.

Sometimes melted tallow, paraffin oil, or machine oil will open up the throat, by being used in the following manner: Dip the metal out of the pot to about an inch below the top of the well, remove the plunger, pour the melted tallow, paraffin oil, or machine oil into the well and replace the plunger. Cast a few blank slugs. After casting about six or seven slugs, fill the metal pot full of metal, recast blank slugs until you have filled the stick. The effect of the tallow or oil is to break up the dross and dirt into such fine particles, that whatever has accumulated in the throat will be forced out through the holes in the mouthpiece. This will cause considerable smoke in the room unless you have a ventilating system. Be sure to clean your vise jaws and mold after you have finished, for they will be covered with oil. It is not necessary to remove the mouthpiece for this operation so consequently considerable time can be saved. But if the throat is very dirty, this method will not work satisfactorily.

Cracked Crucible

Crucibles are sometimes cracked from too much heat when the gas is first lighted. When the gas is turned on full at first, the metal in the bottom of the pot is melted before the metal in the upper part gets very hot. This metal in the bottom expands and powerful pressure is exerted on the walls of the well and lower part of the crucible. To eliminate this danger the gas should be turned on about half force for about twenty minutes, or until the metal becomes warm and expanded, after which the gas may be turned on full force.

Ordinarily it takes about one hour and a half to melt the metal and have it ready for use. The small cracks which are made in the bottom of the crucible when first heating the pot will usually be closed by the heat of the burner after the pressure is released.

To remove an old crucible: Dip out as much metal as possible, turn out the fire, remove the four pot jacket cover screws, take off the cover, dig out part of the old asbestos, release the screw that clamps the left-hand crucible lug to the jacket, lift out the crucible, clean all of the old asbestos out of the inside of the jacket.

To put in a new crucible: The pot jacket should be lined with the asbestos about an inch thick on the inside, except in the front part where the burners are located. Place the crucible in position. Care should be taken to see that it fits firmly in its proper position. Pack the asbestos around the crucible, tamping it down with a stick, and filling in all the spaces. Cover the well of the crucible with a rag while packing, so that none of the asbestos will get into the well. On completion of the packing, place the pot jacket cover in position, and fasten it down firmly with the four pot jacket screws, which extend down through the cover, into the pot jacket.

Mouthpieces

One of the most important parts of the pot crucible, is the mouthpiece. The mouthpiece on all standard machines contains thirty holes (size 51), one hole for each pica of the slug, through which the metal flows into the mold cell to form a slug.

At the present time there are two styles of mouthpieces in general use: The wedge mouthpiece which has a gib or wedge to fasten it in the slot of the crucible to make a tight fit; and the screw mouthpiece which fastens on to the crucible by means of screws.

On all mouthpieces small cross vents are cut downward between each of the holes. There is also a vent which is cut from the first hole on the right-hand end of the mouthpiece. The cross vents allow the air to escape from the mold cell as the metal is forced in. These vents play a very important part in the casting of good slugs. If the vents are stopped up with dross or cold metal, the air can not escape from the mold cell. This causes a slug with air bubbles, making a light-weight slug. These air bubbles, when near the face of the type, allow the letters to be crushed in when put under pressure on the press. Also, the entire slug may be forced down, causing much delay in printing.

Care must be taken in cutting the vents in a mouthpiece so they do not extend very far above the top of the holes in the mouthpiece and that they are not too deep. They should be deep in the center and come to a very fine edge at the ends. All that is needed is to get the air out of the mold quickly. Ordinarily this can be accomplished by cleaning the vents with a sharp pointed scraper but be careful not to mar the mouthpiece. When the vents are opened properly there should be a sprue of metal below the vents on the back of the mold about ½ to ¾ of an inch long after the slug is cast.

A vent that is cut too deep will have too much sprue, causing an unnecessary amount of shavings on the floor and about the machine, and sometimes causing machine troubles.

It should seldom be necessary to drill out the holes in a mouthpiece. If the metal is properly cared for in remelting, and the mouthpiece is kept at the proper temperature, the metal will usually flow freely through the holes. However, if it is found necessary to drill out the holes, never use larger than a ¹/₁₆ inch or No. 51 drill, which will not make the holes larger than their original size. When using the drill, it should be immersed in oil after each hole is drilled, to prevent the drill from becoming too hot and breaking off in the hole. Enlarging the mouthpiece holes will work satisfactorily on large faces 8-point or above; but when the smaller faces are used the product will not have a clear-cut face.

To Remove a Mouthpiece

When it is necessary to remove a mouthpiece for cleaning out the throat of the crucible, mark a line on the face of the crucible to align with the first hole on the right end of the mouthpiece. When replacing the mouthpiece the line will be your guide. By so adjusting there will be a full hole on each end of the slug when casting the different lengths, with the exception of half-pica measures. A hole on the adjustable or left end being partly covered by the liner in the mold would cause no trouble. If part of the first hole should be covered by the constant liner, the first letter on the right end of the slug would be blurred, or would not cast sharply, because the metal cools quickly on the ends of the mold, and a full, free flow is necessary.

The mouthpiece should always be removed when the metal is hot. If removed when cold there would be danger of breaking the pot crucible.

When removing the wedge style mouthpiece, place the vise in second position, lift out the mold slide, place a block of wood between the right side of the pot jacket and the slideway, drive the mouthpiece toward the keyboard, using a piece of brass as a drift. The above operation is necessary to loosen the wedge. The instant the mouthpiece moves, the wedge will become loose and can be lifted out.

Another method of removal is to grip the left-hand end of the gib with a pair of pliers, pulling the end of the gib forward and wrapping it around the pliers, prying against a piece of brass rule placed along the face of the mouthpiece. Care must be used in this method to hold the pliers at such an angle that the lip of the crucible will not be damaged while removing the gib.

Always have a new gib on hand before removing a mouthpiece, for it is difficult to use an old one in replacing a mouthpiece.

In replacing an old mouthpiece, extreme care must be taken to see that it is perfectly clean and straight. Clean the mouthpiece thoroughly and with a straight-edge test the mouthpiece to see that it is straight. If not, straighten it, being careful not to damage. This need not be done with a new mouthpiece.

Before placing the mouthpiece in the crucible, remove the left-hand vise locking stud nut and pull out the stud. Be careful not to lose the small brass washer which is on the stud. The removal of the stud permits the sliding in of the mouthpiece easily. The lips and the slot of the crucible, which are the seat for the mouthpiece, must be entirely free from all dirt and dross or the mouthpiece can not seat properly.

It is best to fit a mouthpiece to its seat by placing a very thin coating of fine emery and oil (fine valve grinding compound is good) on the back and top part of the mouthpiece. This method cleans the seat of all the accumulated dross and dirt. Place the mouthpiece in position in the pot so the top of mouthpiece is against the top seat and move back and forth, bearing lightly against the mouthpiece, until the high spots are ground down, so as to have the seat straight. When doing this, care must be taken not to get the paste on any other part of the machine, as it might cause trouble. The metal should be at casting temperature while fitting a mouthpiece. To hold the mouthpiece for this operation, procure a piece of wood furniture the same width and length of the mouthpiece, fasten this to the mouthpiece by driving a headless brad in each end of the wood directly in line with the last hole on each end of the mouthpiece. By placing the wood on the mouthpiece the brads pass through the two holes and make a very serviceable holder.

After fitting the mouthpiece, thoroughly clean all parts of the crucible lip, slot, and mouthpiece. The least particle of grit may cause trouble.

Fit the gib by dressing it, so that it will drive far enough to the right to make a tight fit. Cover the top and bottom with a thin coating of red lead and oil. Place the mouthpiece in position, the first hole in line with the mark on the crucible. Insert the wedge in the lower side and push it in as far as possible with a pair of pliers. Then drive in the gib so as to secure the mouthpiece firmly. Be careful that the mouthpiece does not move as the gib is being driven in. Lay a brass rule against the whole length of the gib and tap lightly with a hammer to firmly locate the gib on the seat, and at the same time, bring the outer edge of the gib slightly below the face of the mouthpiece.

After driving the mouthpiece to its proper position see that the ends are not burred; if so, file them off, as they might prevent the mouthpiece from locking up properly against the mold, and cause a back squirt.

The screw mouthpiece is held to the crucible by 13 screws. The screw holes in the mouthpiece are counter-sunk so the heads of these screws will not extend beyond the face of the mouthpiece.

To remove the screw style mouthpiece from the crucible, use the pot mouth screw loosener obtainable from the Linotype Company. Fit the loosener in the groove of the screw and tap the head with a hammer. As the screws will be tight, due to the heat and dross, this tapping will loosen them without damaging the screw heads. The screws can then be removed with a screw-driver.

Some features of the new mouthpiece are: There is no danger of breaking the lips of the crucible by driving the wedge in too far; it also eliminates the possibilities of battering the ends of the mouthpiece, as with the wedge style; leaking around the mouthpiece and improper setting when taken off and replaced is less likely to occur.

Due to the width of the face, one mouthpiece is sufficient for a slug of any size. This eliminates the necessity for a special mouthpiece for display, which was necessary with the older models.

Before replacing a screw mouthpiece be sure to thoroughly clean the surface of the crucible and the back of the mouthpiece of all dirt and dross. Place a thin coating of red lead and oil on the back of the mouthpiece and place it in position. Tighten the screws gradually, beginning at the ends and working toward the center.

Metal Pot Adjustments

There are two pot leg bushings which fit over the vise frame shaft and project up into the fork of the pot leg. These support the metal pot and hold it in position to lock up with the mold. The position of the pot in relation to the mouthpiece is determined by four adjusting screws in each pot leg and bearing against the bushings. These screws permit the proper alignment of the mold and mouthpiece.

The holes in the mouthpiece, through which the metal passes to the mold cell, should align with the smooth or constant side of the slug, as this side of the mold always remains in the same position. When using the mold liners for the different points of thickness of slugs, the position of the mold cap changes. If the holes should align with the rib side of a slug of large size, when changing to 6-point slug the mold cap would cover the holes, thus shutting off the flow of metal and causing an imperfect lockup or imperfect slugs.

The two screws at the top and bottom of each pot leg are for the purpose of aligning the holes in the mouthpiece with the constant side of the mold.

To make this adjustment, remove the mold and take it apart. Clean thoroughly the mold and mold pocket. Leave the cap off and place the constant part of the mold back in the pocket with a 30-em left-hand liner and a constant right-hand liner in the mold. Remove the plunger pin for safety. Turn the machine until the first elevator rests on the vise cap. The mold should now be in front of the mouthpiece. Raise the first elevator, holding it up with a piece of wood, one end under the head of the slide and the other on the upper end of the vise automatic stop rod. Close the vise. Unlock the mold cam lever, move the mold disk forward by hand so the locking studs can enter the bushings. Turn the machine by hand until the mouthpiece advances against the mold. Release the two front adjusting screws a trifle so the pot legs can move freely while making the adjustment. Release the lock nuts and move the top and bottom screws until the bottom of the holes in the mouthpiece are in line with the constant part of the mold, and the two end holes are showing within the liners. Tighten the lock nuts and the front adjusting screws after finishing the adjustment.

A great amount of lockup trouble is caused by the mouthpiece on the metal pot not locking up squarely against the mold, due to the front and back pot leg screws being out of adjustment or the mouthpiece being warped.

To adjust the pot legs so the mouthpiece will lock up squarely with the mold, place the machine and the mold (without the cap) and the 30-em liners in the same position as when adjusting the height, but have the mold cam lever connected to the mold slide. Leave a little space between the mold and the mouthpiece. Place a piece of tissue paper at each end of the mold between the mold and the mouthpiece. Have the paper just inside the ends of the liners. Turn the machine forward until the pump lever is ready to go down for the cast. Be sure the plunger pin has been removed, to prevent accidentally forcing the metal out of the pot.

If the left-hand paper should be tight and the right-hand paper loose, loosen the front pot screw at the left and turn in on the back screw. This will move the left end of the mouthpiece farther back. Adjust with the front and back screws in this manner until both papers are held tightly.

After completing the adjustment, replace the cap on the mold and turn the machine to normal position.

Another method of testing the pot lockup is to let the machine make the quarter revolution which brings the mold in front of the mouthpiece. Disconnect the mold lever and pull the mold slide forward. Apply a thin even coating of a mixture of red lead and oil, or printers’ ink, to the back of the mold. Be sure to have the mold clean. Hold out the mold disk driving pinion, so the disk will not revolve, and let the machine run around without casting. The mixture will transfer from the mold to the mouthpiece. If the mouthpiece is touching only on one end of the mold it can be adjusted by the screws in the sides of the pot legs. Adjust them to swing the crucible to bring about a tight fit, repeating the above test until the transfer is registering evenly the full length of the mouthpiece. After each test wipe off the mouthpiece and mold, for any oil or too much red lead or ink would give a false impression.

If the mouthpiece touches at both ends and not in the center or in the center and not on the ends, it indicates that the mouthpiece is warped and the above adjustments would not be satisfactory.

When the mouthpiece is warped or high, it is necessary to take out the high spots with a fine file or an oil stone. Take off a very little of the surface at a time and repeat the tests with the red lead until a proper lockup is secured all the way across the mouthpiece.

After fitting up a mouthpiece in this manner, the vents should be cut to their original depth.

After making the pot adjustments, test the mold slide adjustment to make sure that it brings the face of the mold to within .010 of an inch from the face of the matrices. See that the pot lever has the ¹/₁₆ of an inch play needed during lockup.

Be sure the washers on the pot lever shaft are so placed that the sides of the lever do not bear on the cams.

Pot Lever

The pot lever is located directly back of the metal pot and, through cam No. 8 and the pot cam roller, gives the pot its forward and backward action. There is a cushion spring on the pot lever eyebolt that connects the lower end of the pot lever to the pot jacket. This spring gives the lockup of the pot and mold and takes up all excess motion of the lever during the lockup.

There is a short piece of pipe pinned to the eyebolt inside of the spring, which prevents having too much tension on the spring. The nut on the front is the adjusting nut. This nut has a washer next to the spring, to keep the spring from being forced over the head of the nut. This nut should be tight against the pipe. With the end of the rear nut against the pipe on the bolt, there should be ¹/₁₆ of an inch from the back of the pot lever to the head of the nut when the machine is in casting position. This ¹/₁₆ of an inch adjustment gives the correct lockup to the pot and also prevents breaking the lever by too much pressure.

The pot lever spring should be examined frequently, as back squirts will be caused by a spring which is broken or worn. This trouble is caused by not giving pressure enough to the mouthpiece when it is being locked against the mold for the cast.

A lever spring weak, worn, or out of adjustment will also cause an uneven height of the matrices, due to the lack of pressure during the cast.

When it is necessary to remove a pot lever spring, pull the pot forward by hand, place a support beneath the pot jacket to hold the pot lever roll off the cam. Remove the pot balancing spring, take off the rear nut on the eyebolt and push back on the lever. The spring can then be removed.

The roller in the pot lever has nine anti-friction roller bearings. These rollers should frequently be examined for wear, and if found worn should be renewed, because a set of worn anti-friction rollers will also cause an imperfect lockup. When renewing these rollers, put in all nine new ones. If a roller is worn or broken, or the bearing pin or pot lever roller worn, there will be play between the lever and cam, which will prevent a tight lockup.

To take out the pot lever: Pull the pot forward by hand, place a support beneath the pot jacket, remove the balancing spring, loosen the screw in the upper shaft bearing, and pull the shaft out. On the upper shaft bearing on each side of the pot lever, are washers of varying thickness. These washers are for the purpose of adjusting the pot lever sidewise so it will not bind on the main cams. When taking out this shaft be careful that the washers are not lost or mixed.

Take out the wing pin that holds the eyebolt to the pot jacket. Place the lever on the bench and take out roller bearings by releasing the set screw and pulling out the roller pin. Before replacing the bearings, in the lower roller, coat them with vaseline or hard grease. By placing a small piece of an old keyboard rubber roll in the hole, so the bearings fit around it, they will be held in place until the pin is slipped through. The pin will force the rubber out.

Fastened to the back of the pot lever, at the right-hand side, is the pot return cam shoe. As the main cams revolve, the pot return cam, fastened to cam No. 9, comes in contact with the shoe, pulling the pot away from the mold after the slug has been cast.

Removing a Pot

To remove a pot from a machine: Remove the plunger, dip as much metal out of the pot as possible. Lower the first elevator to the vise cap, and let vise down to second position. Remove the mold slide. Take off the pot leg caps. Loosen the front adjusting screws in the pot legs. Loosen the nut on the pot lever eyebolt, to release the spring tension. Take out the pot lever shaft, and remove the pot lever. Take off the mold disk shield and pump stop bracket. The pot can then be lifted out by placing a rope through the supports on the jacket for the pot lever shaft, so that the pot can be raised up while it is being guided out of the machine by taking hold of the bottom of the pot legs.

Slug Troubles

An imperfect face on slugs could be caused by any of the following: Holes in the mouthpiece not inside the slug line, holes in the mouthpiece closed, or partly so; vents in the mouthpiece filled up, or insufficient ventage; dross in the throat of the pot back of the mouthpiece, mold cell rough inside, due to being damaged; mold cell dirty or oily, inferior metal, holes from the pot to the well stopped up, plunger not clearing the well holes, plunger or pot well dirty, governor not working properly, temperature of the metal not adapted to the size of slug being cast, cold metal. Too large a hole in the mouthpiece will give a small slug an imperfect face.

When the slug is cold, the body of the slug may be solid and have a stringy or flaky appearance, and the face may be imperfect, some of the letters being poorly cast or blurred. The base of the slug usually will be good.

When the slug is too hot the face is good, but the body is hollow and spongy and the slug is light. It is imperfectly formed, due to the heat of the metal.

A bright bottom on a slug shows that the mold knife has trimmed a thin layer of metal from the bottom of the slug, due to an imperfect lockup, the excess metal running over the bottom of the mold. If the mouthpiece makes a perfect contact with the mold at the moment of casting, there will be no excess metal and the slug will show a clean bottom.

An imperfect lockup can be caused by any of the following: Cold metal due to low gas pressure, dirty burners, gas burning in mixer, improper packing around the mouthpiece, or improperly packed metal pot; hot metal, too much metal in the pot, dirty plunger or well, air vents cut too deep, air vents cut too high above holes, dull mold knife, pot cam lever roller or bearing pin worn, pot lever not working freely on the lever shaft, due to gum or lack of oil; metal on the bottom of the mold, mold knife out of adjustment, mold disk guide out of adjustment, leaky mouthpiece, warped mold, pot lever spring weak or broken, accumulation of metal back of the mold disk, mold cap guides bent, loose stay bolt, loose adjusting screws on pot legs.