Suspicious Scumming

[turbotom1052]

does the ring repeat itself from the gripper to the tail? if so just measure the distance between repeats and see if this distance corresponds with the circumfrence of any of the rollers in your water system.

 

[Aljenn]

One possible problem, if you have an automated clean up system, your system may be dripping blanket wash. Does the press occassionally blind out the inks, and then after 10 or so sheets clean back up.

 

[jtdoonz]

If it's a dead spot in roller it wouldn't hit in the same area on every impression. If it's moving then yes it might be a roller. If it is repeating itself like railroad tracks then yes it has something to do with rollers. Either the rubber or your bearings. You should see a dead spot by inking up and checking nip stripes around the roller. If it's in the same exact spot you must have something under blanket or low spot under plate cylinder or something coming in contact with cylinder or sheet. It would help to see a pic. Well Good Luck!

 

[jtdoonz]

Also check nip between cylinders to check that they are set properly. You can ink up plate and throw it on impression to check hit between plate and blanket and back cylinder. It's good to know this is all set and that you are packed correctly. You said you are new so it's nice to go through your press to know that you're are within specs

 

[FSA]

Deadspread4
Welcome to printing. Since you said your new to the game let go back to the basics. When setting roller alway set them in the print position, when the rollers are down on the plate, if you don't you will get a false nip reading. Is there a second shift on the press? I had a ring show years ago, it was the night shift and he put a peice of paper under the blanket to fix a low spot, why he didn't just change the blanket is be-on me? The packing could be creeping forward under the blanket and that also will cause issues fast. jd34tab made a good point to desensitize the chrome roller in the water system(should be done monthy anyways). And you could try droping the etch in the tank, turn off the cooling and fill it up will hot water and let it circulate and see if it stay clean, maybe a slime growth in the line. That happens when you run an etch that has phosphates in it(I run phosphate free Prisco 2451 plus 2). Finally I would suggest you start a journal and write down your problems and solutions, maintaince and log parts, rollers and blanket changes, it will help in the long run. Good Luck
FSA

 

[ziggy33]

I have a AB Dick 9985 same as ryobi 3302 and my press tech also said new rubber in the crestlines when my press was running way to wet for no particular reason but it did not fix my problem so you really gotta check everything over before you go footing a big bill that might not even resolve your current problem.

 

[Deadspread4]

Thanks guys for all the advice. Turns out the press needed new rollers all around, the crestline water train was especially needed. Been 5-6 year since the rollers have been replaced. It is thoroughly washed at the end of everv day, as well many color changes, so im thinkin thats a pretty standard lifetime. Been a little over a year since the replacement and everything have been running great, no adjustments at all. Thanks again

 

[FSA]

That's why a journal is good, you can look up what parts went in and when.

 

[timc]

maybe you should have swapped the rollers from a known good unit onto the problem unit This would have nailed the issue quicker
Like whats been said its all about elimination