Hi All, Great to see this place. Was researching a problem and stumbled in here and found some relevant info about "gear lines". I'm still stumped though. I don't see any side to side play in my form rollers, have checked all my pressures, correctly I hope. Tried a variety of solution strengths with two different fountain solutions. Seems to be happening on both metal and poly plates but I was able to print a 3000 run with blue ink and metal plate. A short run of 300 went fine with red ink and a poly plate but a similar job with black ink toned up with gear marks right away. Tried using a different brand of black ink, didn't work, attached is a picture of that where you can see the horizontal gear marks which show up on the blanket first and then on the paper.
My form rollers are fairly new. My Compac water system was recently rebuilt with new rollers, but I am noticing some swelling already.
Anyone have any ideas what the heck is going on??? Getting desparate! Thanks in advance.\
Gordon
I'm still stumped by this. Rechecked all of my pressures, everything is as light as I can make it. Switched back to using regular blanket wash, including the Kompac rollers. Was using "Suredot" on just the Kompac rollers, and a low vapor blanket wash substitute for the rest.
Your photograph is what I would consider strong evidence that you have too big a difference between the surface speed of your blanket and the surface speed of your plate. Unless you have a broken or seized bearing on a form roller, it is almost certain that this is your problem.
Subtract some packing from either your plate or blanket. If you are still able to print, see if the streaking gets better or worse. If it improves, you are done. If it gets worse, you need to increase the height of the surface you reduced. Having the plate and blanket moving at different speeds will lead directly to this exact problem. The amount of pressure between the plate and blanket is important, but not as important as having the two surfaces moving at the same rate.
Please let me know what your results are, as there are a few other threads on PrintPlanet that could benefit from a clear example of this problem.
Daniel, thanks for the helpful idea. I've used no packing at all so can't take any out. I tried adding a trimmed down 7 mil poly plate underneath the blanket, resetting pressures to the two neighboring cylinders and the problem seemed to get a little better, but not 'cleared up' by a long shot.
What press is this? If you have some printers pumice or Ajax will work try scrubbing the water rollers with pumice and a wet rag. Rinse this out real well then try printing again. If this shows no improvement I am guessing this is a duplicator like an AB Dick. Could be your clearance from plate to blanket is to close as previously mentioned. You will probably have to have a mechanic come in and measure the gap with feeler gauges with the blanket off. I have seen this though when my crestlines were getting shot. After the cleanser scrub maybe follow up with either a calcium rinse or vinegar and water mixed 50 50 then follow up with water
I had an old 1250 that printed great but I had it set up too close to the door and some prick stole it while I was in a meeting. I came out to investigate why we were behind on a particular order and the pressman was standing there astonished saying "it was there when I went to lunch!"
Presses like 1250's and larger presses where people forgo packing for the sake of convenience often find themselves in this circumstance. Perhaps your blanket is thinner than A&M suggested back in the day.
You should check to make sure all of the bushings that hold the rollers contacting the plate are in good shape and well lubricated. If a roller is having trouble turning freely you can get the same thing.
It's possible that the problem could be attributed to either a ducter setting or form to plate pressure. The attachment may not apply to the Multi1250, however it is a good reference.
I was facing the simillar type of problem on web offset bearer to bearer press, i have tried every thing from roller changing, impression setting to bearing replacement, finally we changed the bearer of the cylinder & but problem was solved after replacing the water purifier.
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