Service Bulletin: SB 085.1
Subject: Printing Template — Pre-Printed Rolls
To provide a convenient means to check the accuracy of the printed art work on a pre-printed roll of sidewall stock, prepare a precise drawing of the blank development, including the photo register mark and web width on a dimensionally stable material such as mylar film.
Using a commercial step and repeat camera system available from most graphic arts suppliers have the blank drawing printed on a photo positive material in a repeated pattern equal to the specified feed up dimension. The number of repeats should be one more than the number of printed repeats on the printer plate cylinder. For example, if the art work is four around, have the image photographed in five repeats.
The positive template then can be put over a pre-printed web of stock positioning, the pattern to match the printed number around. The operator can then determine the amount of any error in the printed web as measured from one impression to the next. By adding and subtracting the variance from the specified feed up for five consecutive impressions, to use one example, an adjustment can be made to the sidewall feeder advance. This adjustment is done through the zero max unit on the side ‘of tbLe photo register system’s differential gear box.
This adjustment will either increase or decrease the blank length and may require further adjustment on the machine to allow for the blank difference in the top curl or bottom forming of the finished cup.
If the adjustment requires such an excessive change in the blank’s length that it effects forming quality, then it will be hecessary to reject the printed roll of stock.