L28 scratching

Discussion in 'Komori Printing Presses' started by jetscreamer, Jan 15, 2016.

  1. jetscreamer

    jetscreamer Senior Member

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    hi I'm getting a scratch on the back of a sheet when I back up. Stock is 350gsm and thicker, It is in the middle of the sheet and is 2 scratches about 1cm apart, the only thing I can think of is the sheet guides under the transfer cylinders.
    Any ideas?
     
  2. Meny

    Meny Senior Member

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    check for dirt & dry ink , on the guides and the delivery.
    if you print the same on lighter stock no issue ?
    so it is due to the flex of the sheet making it hit something on the way...
     
  3. jetscreamer

    jetscreamer Senior Member

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    hi yes on lighter stock there is no issue, delivery is clean, turning off all delivery suction has no affect, stopping a sheet after swing grippers reveals no scratches and stock is long grain.
     
  4. Meny

    Meny Senior Member

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    how far from the gripper side will the scratch begin ? and how far to the tail edge ?
     
  5. jetscreamer

    jetscreamer Senior Member

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    Meny sheet size is 650x455 lg. The scratch starts about 300mm down and continues for about 125mm, I don't get any scratches through my colour bars on the back edge of the sheet.
     
  6. alibryan

    alibryan Senior Member

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    It's almost for certain that it's the sheet guides under the impression cylinders. Fortunately, you should be able to slide them out of the way and print fine without them.
     
  7. jetscreamer

    jetscreamer Senior Member

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    Alibryan how do you get to the sheet guides? I don't see how I can crawl through from the feeder end and there doesn't seem to be a way between the cylinders.
     

  8. alibryan

    alibryan Senior Member

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    If I remember correctly, you can open the side door from the feeder end and shine a light all the way through to the delivery. You should see the guides clearly and if you're agile enough, you can reach partly in there and reach the first guides (there are two rows of them). The second row should be reached from the delivery end after you remove the panels that cover one of the pumps.
     
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