Registration probs

Discussion in 'Heidelberg Printing Presses' started by mantman, Apr 10, 2019.

  1. mantman

    mantman Senior Member

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    Hello, i have registration issues on a GTO52 single color that baffle me and could use a second opinion.

    My misregistration happens at OS than DS, sadly i use the only working side guide which is OS, so there is no way to check the other side.

    Studying the movement of sheet while turning the machine by hand, i noticed that when swing bar grapples sheet, OS front lay nicks -no tearing but a small buckle- just a tiny bit as if the front lay bar is a bit late to open. The impression cylinder grippers grab the sheet with close to 1 mm difference.
    I tried the inner front lays but paper is 35x50 and cant hold steady register at all.

    When turning the guides to mid grip i did not notice any nicking but the dancing cross still remains, while going max grip i see the nick/buckle effect at middle of sheet!

    I cannot say for sure that swing grippers are stuck since i tried with narrow strips of tissue paper and pulled away and there was a firm drag at all grips and there is no jog at spring rods -not one i can see or feel from my experience-

    Also front guides are not bend, since i measured from tail of sheet to edge of feed table and was square.

    Height adjustment of side guide is correct -2 sheets sliding between feed table and side guide-

    Could it be that the feed table is higher or lower?

    Any ideas fellas?
     
  2. alibryan

    alibryan Senior Member

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    If you're referring to one or more of the swing grippers being sticky, maybe try flushing with a little solvent, run press for a few minutes and then after that evaporates, spray some lubricant on the shaft. That may help.

    Probably not that simple though.
     
    Last edited: Apr 11, 2019
  3. junker1984

    junker1984 Senior Member

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    Hey Mantman, There are so many possible causes that may lead to the issues you're describing, it would be difficult to give guidance on a forum such as this. Because you say when manually bringing the sheet to transfer from feedboard to swing bar, and the OS is clearly nicking the sheet first, that is because it's farthest away from the cam follower. Given no one has changed the jack jack bolts for feedboard height, it's not likely changing that will resolve your issue. (There should be .46mm gap between feedboard and front lay with lays drawn to minimum grip, while lays bar is at guiding position.) Most obvious cause of your issue, to me, is that your cam follower is blown. Follower is difficult to check, unless there is a visual giveaway, like rust, scoring or flat spot seen. I check the follower with a small telescoping magnet, bringing the follower to a position where you can access it before it arrives at the closing cam assembly near the feedboard. Once there, latch onto the follower with the magnet and check for "play" in the bearing. If that appears OK, the next item will be the closing cam itself. There's an eccentric bolt directly under the feedboard, again, difficult to access without removing at least one of the GS front pile standards. The eccentric bolt has a 17mm hex, so if you can get to it, see if the set screw has broken free by getting a 17mm wrench on the hex and check to see if the eccentric bolt turns freely. There's other causes to this problem, but these would be the most common. Good luck, but I do suggest you call in an experienced tech.
     
  4. mantman

    mantman Senior Member

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    I did change the height of feed table in the past OS side but changed it back awhile ago, i suspect though that its the rod that pulls open the front lay bar since there is a small amount of play and the movement of the rod -along with the erm small hole to oil occasionaly- is a bit wobbly, not firm at all. Also there is a small thump i feel on the front lay bar when swing gripper comes to grab paper -that could be cam follower but only at high speed 5.5 to 6 iph- but i cant see it at all. As for rust there was plenty all around but did manage to clean as much as i could though at that point i could not reach even from delivery side
     
  5. junker1984

    junker1984 Senior Member

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    1555007231188-1412280335.jpg You won't be able to check the follower with your fingers, has to be a small telescoping magnet or long shanked, small screwdriver to manipulate the follower bearing. Its clear to me you dont choose to dismantle anything to make these checks, so the above is really the only way to do so. As for the operating rod of the closing cam assembly, a small bit of play may be ok. I misstated earlier regarding the eccentric, that's for opening to impression cylinder. Hope I didn't confuse you too much. You will also want to check the closing cam flange (item#3) to see if the bearing in the frame has failed. To do so, just be sure the follower is back, away from cam. Rock flange up/down while also moving side to side. You'll know it if it's too loose.
     
  6. mantman

    mantman Senior Member

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    Many thanks for your precious input junker
     
  7. junker1984

    junker1984 Senior Member

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    Hope it helps!
     
  8. mantman

    mantman Senior Member

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    Tech came today and noticed that there is a jog between flange and rod starting from number 7 although he did notice table to be uneven with front lays -unless as he stated that marks are worn out- and swing gripper might need to come off and timing might need checking, now we wait cost of all these so my boss can decide
     

  9. junker1984

    junker1984 Senior Member

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    Ok, Mantman, be sure to pay attention to the possibility that the taper pin at #6 may be worn, allowing the swiveling lever to be causing swing gripper timing issues, and the pounding at higher speeds. IMG_20190412_184931.jpg
     
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