Ryobi 3302 image perpetually crooked. Help?

[lantz_xvx]

Hey everyone,

I'm back with some basic Ryobi 3302 troubles. I've got a ten month old kid so I'm super part time at the shop right now, which means that I don't have a lot of solid blocks of time to really figure the press out the way I need to.

Right now I'm struggling with image crookedness. I'm running 130# uncoated cover stock cut to letter size. The paper is cut square, and I'm using poly plates.

I mount the plates according to the measurement guides on the cylinder, so if those two measurements match, the image should be pretty straight, right? But it's skewing toward the OPS on both heads (not just one), so it seems as if the problem is in the feed / registration.

I have to trim the plates a little bit to go through the HP5500, so it's possible that when I trimmed them, the blade was slightly out of adjustment and the plates were not totally square. Would that make the image EXTREMELY crooked, though?

Or is the side guide hitting incorrectly? Maybe it's pushing too far, and hitting too hard, so that it skews the sheet? Would there be any sort of mechanical issue that would cause this? Any help would be appreciated.

Thanks,
- Lantz

 

[Al Ferrari]

You can test if it is a sheet travel or feeding issue by printing a few sheets at normal speed, then walking one through on impression watching that it has gone in straight. Don't side guide it so as to remove that as the cause. This slow one may print light, but you are looking for straightness.

If the slow one prints crooked, then you should check out your plate cutting method.

Regards to the wife and kid.

Al

 

[RGPW17100]

You should be able to verify how straight you are cutting the plates using a tee square on a light table. Put one sheet on the feed table of the press and advance it till it just gets to the head stops adjust your side quide so that it is square.

 

[pdan]

I have to ask, have you verified/measured the image on the plate?
I have two imagesetters. One does not produce perfect rectangles. Measure the image on plate 8 times - twice from four all sides. Is it straight and square.

You indicate you're running down on x & y axis. (Tail to the ops side). Have you checked register? can you run 50 sheets, change nothing, put them back though. I've been known to double pass 500 sheets (when caught on a phone call with no ink in the well) and the double pass looks identical to the single pass sheets on a 3302.

 

[lantz_xvx]

Thanks for the replies, everyone. It actually turned out to be something really idiotic: upon re-inspection, I noticed that the spring guide on the operator side that gently presses against the stack was, in fact, nowhere near it. It must have jimmied loose when I lifted the loading mechanism to load more paper. Although the sheet didn't really look visibly skewed traveling down the table, it must have been erratic with no side guide. How I didn't catch it is beyond me. Probably just in a rush and not thinking about the easiest (and usually dumbest) explanation.

Lesson learned: check EVERYTHING before you hit the feed.

I ran some test sheets yesterday after realizing this and everything came out fine. I'll be reprinting the job today.

Thanks again,
- Lantz

 

[Reyn Hubbard]

Two things come to mind. Start out with the plate scewing studs backed out far enough for the pegs next to each one to bottom out. Then, only adjust scew if the plates do not trap correctly. Measure the image with a ruler on the lead edge of each plate to determine if it is square to the lead edge of the plate. That will tell you if imposition is off on platemaking. Our 3302 has a scew compensator on the first unit underneath the cylinder positioning adjuster. Is it set to center? (if your press has one). There is no other reason for plates to print crooked unless the lower feed roll is shot OR the hold down guides going into the cylinder gripper on the first unit from the feed rolls are set incorrectly. The rule in this business is Keep-It-Simple-Son until it no longer is. I have more suggestions if that does not help.
RonH

 

[RGPW17100]

He found the answer to his problem and stated it here. Pretty sure the thread is done