Ryobi 3302 color contamination.

[lantz_xvx]

Hey all,

This is a problem I haven't had to deal with since my days of fumbling with a T-head: color contamination.

I ran a two color job today, just promo stuff for myself so not too big of a deal - black on the first head and PMS186 red on the second. The first pass was pretty much fine (they're double-sided postcards) but on the second pass, where there was more coverage, my Crestline water form seemed to get contaminated with the black from the first unit and transfer it to the rest of the ink train on the second unit. This caused color inconsistencies that isn't a huge problem for what it is, but I definitely can't have that happen on a client's job.

Anyone know what could be wrong? I did notice that since the weather changed, a couple of the form rollers are out of adjustment, causing build-up on the sides of the plate. Maybe that build-up on the blanket was too much and got picked up back into the ink train? Or maybe the impression is set too heavy?

Any help would be appreciated. Thanks.

- Lantz

 

[ziggy33]

could be a number of those things you mentioned but i am wondering why you put your black on the first head instead of the second head?? I always run my lighter color on head 1 and darker color on head 2. In my years of printing on the 3302 I have never had to deal with color contamination running them like this. what are you running as your fountain solution?? your impression should be as light as you can go while still producing a good image.


Jake Z
Ziggys press repair

 

[lantz_xvx]

Yeah, you're right. I guess it's because I've been doing things as test runs and trying to troubleshoot all the issues I've been having one at a time. I was having trouble with my first unit so I started off on that. When the problem I was having was resolved, I figured, what the hell, dump some ink into the second unit and see how that goes. I actually didn't think it mattered which color was on which head, since there was no overlap. Although, now that I think about it, there IS overlap; the crop marks. So that makes a lot of sense now.

As far as impression goes, I haven't really paid any attention to the metric measurements on it. All I need to know is: to increase impression, do you turn the knob clockwise or counter-clockwise? I suppose I could figure this out by starting one way and changing it, while paying attention the image on the blanket. But I was having a lot of blanket build-up and scumming issues (because my plate was not fully snug - I finally got the hang of the quick tension bolt today) so I haven't done this yet.

I'll adjust the rollers to spec tomorrow and switch the colors, and see if that works. Let me know if you have any other ideas though.

- Lantz

 

[ziggy33]

Turn you impression knob counter clockwise to increase pressure to much is just gonna smash up your blankets and then nothing will look good. Yea those quick tension bolts take some gettin use to but easy once you figure it out. Remember you set everything to spec but if they are worn too much it won't make a difference so just make sure nothing's coned to bad
I always say preventative maintance is the best maintance!

Jake Z
Ziggys Press Repair

 

[lantz_xvx]

True, preventative maintenance is key. However, it's an Itek 3985, already old, and then you consider I bought it from the printing equipment dealer equivalent of a slumlord. So, there are a lot of things wrong with the press, large and small, and it's hard for me to where "normal" is at on my gauge of "passable" and "extremely screwed up."

The other thing I just remembered that would certainly cause color contamination is that the image on the first unit blanket somehow transfers to the blanket of the second unit. I'm thinking it's probably related to the fact that the press is always transferring the image on the blanket to the impression cylinder. Yesterday I had to trick it by turning on the feed and then putting it into the print position. It seems that once the first sheet triggers the impression, it works fine. Of course, if you miss a sheet or get a jam, you're screwed again.

I have the repair guy coming on Friday so hopefully he'll be able to get these things fixed. The press is almost there....

- Lantz

 

[ziggy33]

haha yea i bought a 3200 that was like that had to buy a bunch of new parts and reset everything to spec. before it started printing good where i could sell the printed piece. Have fun with that tech being there make sure you watch closely so some adjustments you can do yourself thats how i started learning to fix press'.
Good Luck
Jake Z
Ziggys Press Repair