Double sheet detector

Discussion in 'Heidelberg Printing Presses' started by Ricardo, Nov 21, 2019.

  1. Ricardo

    Ricardo Member

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    hi gentleman’s. I run a Heidelberg 102 zp 1993 color tronic. I’m having a problem with a electromechanical double sheet detector. I’m getting double sheets. I replaced the bearings from the two wheels. They were rusty. I’m still getting double sheets. Looks like it is too sensitive. Most of the time I run 50 lb offset paper. Any idea?
     
  2. junker1984

    junker1984 Senior Member

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    Hi Ricardo, This is usually caused by a "flat spot" worn into the running area of the top eccentric wheel. It's difficult to verify without removal of said wheel, maybe use a mirror to try to see the bottom of the wheel. Replacement of wheel should remedy the issue.
     
  3. NotAGooner

    NotAGooner Senior Member

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    The thinner the sheet, the more accurate the double sheet detector has to be, I always tore 3 strips of the stock being used and fed them through the double sheeter to trip the top wheel, then backed it off a touch, after that I ran the feeder slowly while holding the top wheel so it wouldn't trip and slowly backed it off until I could feel the top wheel move, then screw it back a touch. Hope this helps?
     
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  4. Ricardo

    Ricardo Member

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    This one?
     

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  5. junker1984

    junker1984 Senior Member

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    Yes, how does the running surface look?
     
  6. Ricardo

    Ricardo Member

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    This is a new one. I’m going to replace it tomorrow. I’ll let you know tomorrow. Thanks.
     
  7. Ricardo

    Ricardo Member

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    This is the one in the press.
     

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  8. junker1984

    junker1984 Senior Member

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    Most definitely time to replace it, hope it remedies your feeder issues.
     
  9. Ricardo

    Ricardo Member

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    Do I need to adjust that spring?
     

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  10. junker1984

    junker1984 Senior Member

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    I've not seen any reference to critical dimensioning when reassembling, but suggest you try returning load to original tension. And in the future, when taking something apart you've not messed with before, don't blindly turn nuts and bolts...mark, measure and take pictures.
     

  11. turbotom1052

    turbotom1052 Senior Member

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    This is very true. I don't even bother with the setting with strips of paper. I go right to running sheets down the feed board and closing the gap slowly while holding the upper wheel. As soon as I feel the upper wheel wanting to turn I then let it trip. Once it trips I back off a hair and its good to go. I then like to do a final test of my setting on run speed with a strip of paper. Im a believer in setting it up under running conditions with air blowing through the stream of sheets.
     
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