Timing keeps retarding back.

Discussion in 'Heidelberg Printing Presses' started by Lester Allen, Jan 17, 2020.

  1. Lester Allen

    Lester Allen Member

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    Someone please help me. I run a 29 inch SM 74 heidelberg press. The timing chain was stretched, so I changed it and put press back in timing. Paper meeting head stops at 300 degree. The press will start up and run with a straight up and down line. Then starts to come in late and stops press. So I do the process again and the timing keeps retarding. Ive gone forward on timing about 3 revolutions. There is no way this paper should be coming in late. Is there something I'm missing on the timing. Could it be the encoder? Like I said, it starts in time and then comes in way late no matter how far forward I go on timing. I always set paper to meet head stops at 300 degrees but for some reason doesnt stay.
     
  2. junker1984

    junker1984 Senior Member

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    Remove the small sheet metal cover on the gear side, infeed. This will be the one in between the first unit cover and feeder. You'll find a spring loaded chain tensioner, which is made up of mostly platic parts. I've replaced a number of these over the years. You don't state what model year your machine is, and I can't say from experience if this tensioner is used on newer (post 2000?) machines.
     
  3. Mathew

    Mathew Senior Member

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    Hi,
    In addition to Junker's instructions, there are two pins which can cause this issue too, one is on the wheel connected to steel roller and the other is one the wheel connected to Gordon shaft of Suction head. These two wheels are turning by the chain.

    Good luck,
     
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  4. Lester Allen

    Lester Allen Member

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  5. Lester Allen

    Lester Allen Member

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    I know exactly where your talking about. I'll take a look and thank you.
     
  6. Lester Allen

    Lester Allen Member

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    I'll take a look. Thank you very much.
     
  7. asem alsafady

    asem alsafady Senior Member

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    Dear Lesrer,
    Did you solve the issue.
    Please send us feedback.
    Many thanks.
     
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  8. turbotom1052

    turbotom1052 Senior Member

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    if memory serves me correct i believe you can turn off that feature in Cptronic or cp2000
     
    Last edited: Jan 27, 2020
  9. junker1984

    junker1984 Senior Member

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    Damn. I hadn't even considered the possibility that the issue is in automation, not mechanical deficiency. Good catch, Tom. If this is the case, a thorough inspection of the servo drive mounting and lead screw condition should be done. Reflex sensors come into play also, check for stability in mounting.
     
  10. asem alsafady

    asem alsafady Senior Member

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    Dear laster,
    In addition to all what gentlemen said.
    First, I saw some cases they have a problem in the chain itself, if the chain is wear it can cause your problem, check it.
    Second, check if the clutch stops in the same position every time.
    Third, check the sprocket wheel (where you adjust the timing) for any jamming.
    Finally, check the sitting of the forwarding rollers before you start making the timing.
    Good luck.
     

  11. turbotom1052

    turbotom1052 Senior Member

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    AWWWW shucks
     
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