GUM POT. The gum pot can be fitted with two different types of gum applicator rolls which are available to suit varying conditions found when operating the machine. The same gum pot is used for either form so that in a few moments time, one type can be switched to the other type and back again. Each user should determine which type best fits his requirements. When using hot gum the Form D rolls are usually used for wrap-around labels. They consist of a series of rubber discs mounted on metal cores which are fitted so that they adjust when the machine is adjusted for height of can. See special instruction sheet. The Form H applicator rolls are generally used when applying spot labels using either hot or cold gum. They consist of two hollow cup rolls made the full width of the label in order that the gum may be applied to the container approximately the same width as the label. Since the rolls are hollow, they will flex thereby helping the spotting of gum on paneled or dented cans. For this Form H gum roll, see special instruction sheet. It should be kept in mind that since the gum rolls are the same in width as the label, one is required for practically every width of label.

GUM ROLL ROCKER ARM. An adjustable rocker arm supports the gum rolls permitting a more positive application of the gum because it is movable. When the cans roll over the gum rolls, this arm should move down at least 1/32". This movement can be maintained by adjusting the set screw on the rocker arm and resting against the pot. After adjustment always be sure to lock the nut under the set screw so that adjustment is maintained. See special instruction sheet.

SCRAPERS. Scrapers are provided on the gum rolls to remove the excess gum from the rolls. It is important that they are set properly to maintain the proper feed of the gum. Incorrect setting will cause the gum to collect on the edges of the top outside rolls which will transfer the gum to the can tracks, thence to the cans and finally on the carrier belts which in time will cause the belts to tear off the labels on the cans which are already labeled. Set the top scraper close enough to the roll to allow a very thin smear of gum to be deposited on the cans. The operator should bear in mind that too much gum is just as troublesome as not enough and he must determine the proper amount from actual operating experience. See special instruction sheet.

THERMOSTAT. Located in the gum pot is a direct reading thermometer to give the actual temperature of the gum in the pot. The temperature of the pot, however, is automatically controlled by a thermoswitch mounted in the gum pot base. This thermoswitch is set at the factory for a variation in temperature from 200 to 300 degrees. However, it is possible to increase or decrease the range as follows. If it is desired to change the range, say from 140 to 240 instead of from 200 to 300, the pot should first be heated up and the knob turned to its extreme limit to give the lowest temperature possible. Located in the brass collar behind the black adjusting knob are four threaded holes with a stop screw in one of them. By removing the screw and placing it in the next hole, it can be seen that the temperature can be decreased still further. If it is kept in mind that moving the screw to the next hole to it increases or decreases the temperature range approximately 20 degrees, it can be noted that moving it 2 spaces would increase it 40 degrees, and 3 spaces 60 degrees. Therefore, if the range of the thermoswitch was between 200 and 300 degrees and it was desired to change it to 140 to 240, the set screw would be moved 3 spaces allowing the knob to turn lower by approximately 3/4 of a revolution. It is very important to be sure that the heat has been on in the pot long enough so that the temperature is correct before any changes are made. The top temperature of the thermoswitch is approximately 400 degrees and therefore the screw should never be moved if the thermometer is already reading that temperature. Likewise, the bottom temperature is 100 degrees and no attempt should be made to adjust the temperature below it. Always keep in mind that there is a time lag between the resetting of the thermoswitch and the indication of it on the thermometer. Therefore, when one change is made, at least 20 minutes should be waited until a further change is made thereby getting true readings of the first change before another is made.

OPERATING INSTRUCTIONS. When operating the machine, be sure that gum rolls are free to rotate on their shafts since on the Form D rolls, the outside ones have flanges which run in grooves on the underside of the can tracks, and therefore move with the tracks. It is a good idea,

if the adjustment is seldom made to pull out the shaft and rolls before adjusting and then replace after adjustments since this will eliminate the possibility of springing the tracks or breaking the guide pins. It is very important to always disconnect the gum pot shaft on the rear side of the machine at the end of a run, since the hot gum solidifies when it cools down to room temperature and freezes the whole turning mechanism. Likewise, when starting up the machine, do not reconnect the shaft before the gum has heated up long enough to become liquid and the shafts turn freely by hand.

A thorough inspection and test is made of the machine before it is shipped from the factory. However, the users warehouse and container conditions may vary considerably from the conditions under which the tests were made, therefore the operator must determine by his own experimentation which type of pick-up gum , what speeds and what temperature will give him most efficient operation of the machine under his own conditions.

Many of the difficulties which arise in packing plants are due to temperature variation of the containers or conditions of the surface of the containers such as wetness or oiliness. Sometimes when moving containers from a cold storage room into a warmer labeling room, the can surface will pick up moisture making them very difficult to label. However, gum can be purchased to overcome any of the difficulties although it is almost impossible to label containers when one is hot and the one immediately following is ice cold or one dry and the one following wet or greasy. Therefore, it is important that the packer maintain uniformity of conditions in so far as it is possible. It can readily be seen that it is impossible for the manufacturer to know the user’s warehouse and container conditions.

When using cold gum, the gum pot switch ordinarily will be turned off. However, if a little heat is required the operator should snap the switch on and off manually watching his thermometer readings carefully.

When using hot gum, always run the gum hot enough that it won’t string. The strings, of course, get all over the machine and in time, make it impossible to apply labels neatly. Some gums, however, will string a little bit without causing much damage, hot gum permits greater flexibility because its stickiness can be changed by the thermostatic controls to meet varying conditions in the warehouse. Furthermore, grease or scum which may collect on the cans has no effect on hot gums. If the gum is too hot, the cans will pass over the label partly picked up, but again drop it and pass through the machine unlabeled. The reason that the label is dropped is because the gum is not sticky enough to hold the label after it picks it up. A lowering of the temperature of the gum will help. If the gum is not hot enough, it will not be sticky enough and the labels will again not be picked up. It must be emphasized that the temperature of the gum is dependent on the temperature of the can since hot cans would require a colder gum than cold cans. A further trouble will result when gum is run too cold because of the fact that the top gum wheels will carry an over supply of gum to their sides. The gum, in turn, will flow out of the can tracks and from thence onto the can. The gum will also leave a large blotch on the body of the can causing a rough lap of the label.

CARE OF POTS. When using cold gum, it is not necessary to wash out the pot every night providing that the machine is going to be used the following day. However, it is necessary to remove the top gum rolls and put them in water. The operator should, of course, see ahead a little bit so that when he finishes up at the end of the day, he does not have much gum remaining in the pot so that a good quantity of fresh gum can be added before starting the next day thus freshing the gum that remains in the pot and causing it to probably work satisfactory.

Likewise, when using the hot gum, it is not necessary to remove it since the gum will solidify as it cools and will not spoil at room temperature for a long period of time. How-

ever, it is important that the gum pot drive be disconnected so that if somebody should start the machine unwittingly, the drive which is frozen with the gum will not break.

The complete pot can be removed for general cleaning by removing the six screws located at the edges of the base and screwed up into the pot. To slide out the pot, push down the rocker arm bracket until the gum rolls clear the underside of the can tracks. Then remove the top gum rolls and all the scrapers including the thermometer and if cold gum was being used, put everything except the thermometer into a container large enough to cover all the parts with water. If it is allowed to remain several hours in the water, it will then wash up very easily. If however, hot gum has been used, the only way to clean it is to preheat it to pour off as much of the gum as possible and then use a high pressure steam hose to blow out the remainder.

When putting the pot back together, be sure that all holes are free from dirt and water and fill the bearings with oil. Make sure that when placing the pot back, the driving gears at the back of the pot are properly meshed before inserting the cap screws and tightening them.