press having register problems

[ninjaPB_43]

so, I dont fully know how to explain the problem, but the press cannot register one unit(not always the same unit) on 70# book, but registers fine on 100# card..  pressman exchanged plate on Mag(cant register) with the cyan, and the cyan began not registering. makes it sound like the punch isnt punching the plates exactly right...   but our other press doesnt have the same problem, and it does register when running cover weight...   anyone got any suggestions of something to look for??

we have already had a tech out looking at the press, and he says he thinks its moisture in the airlines causing an inconsistency in the pressure, but our pressman disagrees continuing to state its the punch, because it followed the plate when he swapped it to another unit.. but the damn cover weight registers..   

HELP?!!   

[gnubler]

HELP?!!   

Go now and get a 12-pack of Coors for the pressman and plan on stopping at the bar after work tonight.

[jimking]

What size press? It could be a problem with his blanket, a packing issue maybe.

[LoganBlade]

what press? is it regitering consitantly in the same spot or is it bouncing . for example only

marks of each color are .125" apart and you can't get them to match and they are printing outside of marks that the marks want to come in  to the center on 1 plate to match the other.

What kind of Press?

[Santa]

Misregistration is usually a few points and there is a few points difference between cover and text depending where your at so that could explain why one registers and one does not.

The fact that the misregistered plate followed when it was switched between the press units leads one to think it would be a plate issue.

Check your punch and make sure it is all clear, sometimes a circle can get caught.  Also, take a little rubbing alcohol or whatever cleaner you use and clean the actual punch jackets (i.e the metal circle that make the hole) sometimes plate emulsion can build up over time and harden and it can throw it off.

Lastly, measure your plates.  Maybe a bad batch of plates got out there and they may be a centimeter or two off which could cause this as well.

After that I'd follow gnubblers advice.

[Goodgulf]

If the cover weight registers just fine then it is not a plate issue

My guess would be a packing problem

[LoganBlade]

depending on press it could be a gripper problem holding tight on the heavier stock and letting sheet go early on lighter

[ninjaPB_43]

first off, thank you very much for the quick replys.

It is a Heidelberg SM74. 

Secondly, the questionable punch(as explaned to me) is NOT the issue right this minute, because there are other problems they are trying to work out.

We know for sure it isnt the blankets and packing.

as of right now the key possibilities are:

1) moisture in the air lines, this has been dealt with because as of this morning, they FINALLY got the air hooked up to the house air instead of a pump(which is believed to be the cause of the moisture, but it will take some time to get the remaining moisture out.)  This is causing the units to stay on impression or to not fully go onto impression..

2) the guide. this press has no sheet compensator and Pressman believes the guide is "crimping" the paper, but once it transfers past the perfecter it fans back out, causing the first two units to "print inside" the last two..

we are all headed to the bar and have decided that the problem will be gone when we start up on monday.



thanks again.  will still be working on it next week, will respond more in this thread then..

[David]

I had a reply but then you posted more info so I deleted my reply.
the two scenarios you have listed could very well be the culprit.


So,
If you need a ride to the someone to take to the bar, I can help with that....


 

[ninjaPB_43]

I had a reply but then you posted more info so I deleted my reply.
the two scenarios you have listed could very well be the culprit.


So,
If you need a ride to the someone to take to the bar, I can help with that....


 

hahah..  sure, except we decided the golf course was more suitable..  headed to Twin Wells now, as soon as this last proof is run..  you are MORE than welcome to join us, and even if not today, join anytime, we play usually at least once a week..

HAVE A GOOD WEEKEND EVERYBODY!!!   and thanks again for such quick responses.

[Ear]

Yikes! So there's a perfecter in the mix eh? That could be a problem! Does sound like paper being squished or stretched tho. Also, the packing/blanket issue is something to check out. Different thickness on the plate or blanket cylinder will change the circumference and therefore make it print shorter or longer.

[G_Town]

but our pressman disagrees continuing to state its the punch, because it followed the plate when he swapped it to another unit.. but the damn cover weight registers..   

HELP?!!   

That's the first time I ever heard of a pressman blaming prepress for a press issue....weird.




 

[LoganBlade]

did you check how it followed?

sometimes they are so wrapped up in prepress' problem they miss that the fit is wrong but is now the second color printing inside the first color.

[ninjaPB_43]

not a prepress problem..    as time has moved along, with house air lines hooked in, moisture is going away and magically so has the problem..  ???