SX 74 Perf on press

Discussion in '1-Color and 2-Color Offset Presses' started by swilson513, Jul 20, 2015.

  1. swilson513

    swilson513 Member

    Joined:
    Oct 2009
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    Location:
    USA
    Could someone tell me the sequence of mounting a perf sheet on a 2013 2\c SX 74?

    TIA
    Jeff
     
  2. turbotom1052

    turbotom1052 Senior Member

    Joined:
    Oct 2008
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    1,044
    Location:
    Vermont
    I prefer to mount the litho perf on a sheet of mylar, as opposed to on the printed sheet. The mylar is more dimensionally stable, and if need be easier to re position if the perf begins to walk. Not familiar with an SX74, but on Heidelbergs I've run I place the mylar with the perf attached into the headstops by hand, right after engaging the feeder tapes while the headstops are on their way to the register position. After inching the press, and verifying that the side guide pulls to position, I allow the sheet to enter the infeed. I then inch the press until the sheet is in the appropriate position to do 2 things. The first thing is manually engage impression on the unit you will be perfing on. The second thing is to inch the press around until the gripper area of the impression cylinder is available to apply some spray adhesive. Timing of these operations are critical as you don't want the cylinders to be on impression before spraying adhesive, but you do want it to be on impression for the next revolution, when your mylar sheet is about to be handed off to the impression cylinder grippers. I then inch the press around with that unit on impression until impression cylinders grippers are in position to cut off the mylar flush with the impression cylinder body, so that the mylar does not transfer. I ALWAYS use a new razor blade and take my time cutting the mylar tight to the cylinder body. Then its just a matter of opening each individual gripper a bit with a screwdriver, and pulling off the cut mylar from under each gripper. Repeat for the next set of impression cylinder grippers on the same unit, if press is equipped with a double diameter impression cylinder. If you have a press with a single diameter impression cylinder in the shop, and don't mind perforating offline, then I suggest using that press as its half the work to set up as your only doing everything once. Will usually get better results this way too when it comes to multiple perfs and tight perf register.
     
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