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.
GASOLINE BURNER
There are three methods commonly used to heat a metal pot: Gasoline burner, gas burner, and electric heater.
The gasoline burner in most cases is undesirable on account of cost, time, and fire hazard; but through the lack of electrical current or gas it must sometimes be used.
There is a burner designed for either gasoline or kerosene by the Linotype Company. This burner will give complete combustion in burning either gasoline or kerosene. It has no threaded joints and, therefore, no joints to leak. It is equipped with a positive mouthpiece burner and control. This burner can be taken apart for cleaning without removing any screws. The fuel is forced to the burner from a pressure tank. With this improved mouthpiece burner control, the burner may be adjusted for a slug of any size. The best results can be obtained from a gasoline or kerosene burner by keeping it clean.