horizontal gear lines

[PilotPrinting]

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

 

[PilotPrinting]

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.

 

[Dan Roll]

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.

 

[PilotPrinting]

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.

 

[RGPW17100]

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

 

[PilotPrinting]

Da! Sorry, its a Multi 1250W. thanks for the additional ideas!

 

[Dan Roll]

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.

 

[Bob Peterson]

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.

 

[PilotPrinting]

GREAT info, thanks so much everyone. Will report back after I try some off these.
Gordon

 

[printsha]

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.

 

[Alois Senefelder]

Gear Marks

Gear Marks

Hello Pilot Print,


The Cylinder pressures need Setting Correctly - NOT Light - BUT FIRM

Regards, Alois

 

[maas]

have you check your clearances, cylinder to blanket, undercut?, no rollers out of round?

regards
Maas

 

[PilotPrinting]

Seems like replacing the 2 form rollers did the trick, after trying just about everything else!
Thanks so much for all the GREAT suggestions, learned a lot!

 

[PilotPrinting]

the new ink form rollers helped, but the problem still persisted. replaced my Compac form roller too, that helped some more but still didn't cut the mustard. Switch back to plain blanket wash from a substitute that I had been using and that seems to help significantly. Just printed 11,000 impressions, 3 jobs and the work came out clean. If the good results continues for a bit, I'll try switching back to my blanket wash substitute and see what happens. I used to use EcoloClean CD, but had to change to an alternative when VARN discontinued producing it. I seem to have had increased problems since then but can't blame anything, yet. Thanks again for all the great suggestions!!!!!!

 

[RGPW17100]

The press wash you switched to a water misable? If so are you cutting it or running it full strength. That stuff full strength will really mess up rubber. I used to love the Ecolo clean. It was the only water misable that would not separate. Maybe try Varn V120 and mix 50/50 with water

 

[PilotPrinting]

RGP, thanks for the additional info on the blanket wash substitute. Yes I was using EcoloClean CD too, was great stuff!!! I was very bummed when they stopped making it a year or two ago, seems my troubles started shortly after. I was using the substitue straight, seemed to work pretty good that way. Kinda sucked mixing it with water, didn't seem to do a very good job. Will check on the exact brand I was using and post it here. I've gotten about 20,000 impressions now after switching back to straight blanket wash. I really think this was the culprit. Had some other issues too that didn't help, but am 70% sure it was the blanket wash substitute which I was using straight.
Best wishes, you guys are awesome!!!!
Gordon

 

[pressmanken]

gear marks...

gear marks...

I would suspect the plate/blanket cylinder pressure is too tight. The gears could be gummed up with paper dust/crud on an old press with a lot of impressions under it's belt. Packing your blanket may have helped by pulling the cylinders apart enough to keep the gears from bottoming out against each other. As for the water-miscible wash, it works pretty good, as long as you keep it mixed well. I have to shake mine up all the time to keep it from separating. Hope it helps. Good luck. By the way, I have an old 1250 with a T-head, if anyone's interested.