Inking heavy on the edges - Proof Press

ok larger image here:
http://www.clovestpress.com/wp-content/uploads/2013/04/helmuth1.jpg

If you’re running your copy perpendicular to the rollers (i.e. hitting the left edge of the card first), then you might have your rollers set too low. I’d try raising them little by little and see if that evens it out.

You might also check your packing and make sure there’s nothing uneven there, like a stray piece of tape or something. Looks more like roller slur, though.

Maybe this one is a good case for putting a couple of lines of lead rule top and bottom of image in the waste area to help bear the rollers to even out the roller pressure during the inking of the forme .

Peter, I’m printing with polymer and usually have at least a 4pt line rule on running the full length of the image area. If I had this rule and this was still happening does that mean the problem was indeed rollers set too low?

Thats likely so long as you know there are no areas of the polymers edges that are not stuck down and could be lifting at the time the inkers pass over it ,
If you feel the rollers are too low the bearers can be quickly taped temporarily just to verify that ?

Daniel says he is running this on a Challenge proof press, so the only way to deal with low rollers is to adjust the roller height by adjusting the bearing blocks at either end.

It is difficult to tell from the photo, but is impression uniform across the whole image or is there greater impression on the ends of the lines?

John Henry

It looks to me that the right or left side is hitting first and for such a small amount of type this is the weakness of cylinder presses in general. If I encountered this problem on a plate I would back off the packing slightly, and build-up a layer or two of make-ready tissue under the tympan between the beginning and ends of the lines. I think it is a mistake to try to alter the bearing pressure on a proofing press. This looks like a detailed make-ready situation.

Paul

I’ve been watching this thread, as I see this often on my Heidelberg 10x15. Although it doesn’t look like typical slur, I’ve managed it as you would slur, by cleaning and powdering the rails, and occasionally slowing the press down. There has been times when that didn’t do the trick, and the make-ready as Paul described fixed it, so its possible this issue has multiple causes.
But I’m going to try the addition of rules above and below the plate next time as well.
Bill

Paul:

I was just saying that the ink rollers cannot be adjusted by taping the rails — the adjustment must be made by raising the roller support structure which supports the ink rollers. I was not suggesting that the cylinder bearings be adjusted.

The setting of the rollers is accomplished very much like it is on a Vandercook Universal press, and the rollers should have a gear on the rear roller (one closest to the impression cylinder) which drives the rollers as the head moves over the form. It would be good to make certain that the gear is properly attached to the roller shaft, as if the rollers are not turning until they hit the type form, that could cause slur in both directions.

John Henry

I think what Peter is suggesting, is that in order to perform a quick and dirty test to see if roller height is the issue - place tape on the roller “bearers”, which in the case is exposed photopolymer along each side of the image area. Then if that cures the issue the rollers settings could be adjusted as jhenry suggests.

Here is a link to Gerald’s site with a good explanation of what Peter suggested in his first post.

http://bielerpressvii.blogspot.com/2007/07/ink-roller-supports-bearers.h...

I have to admit i did not realise this was a proof press ,however i would still do a physical test with a make shift bodge before adjusting the machine as it can mean you have two problems to deal with one of which you will have created in the hunt for the other .make ready is of course an option too if you need to but that should have been done in the building up of your packing in the first place or does no one go back to standard for a new job?
I know there are some people take the chance on getting away with the first pull but then bashed impression seems to be todays objective so i guess its not as we were taught metal doesnt let you off from a batter like polymer seems to .

Sorry John,

Since I looked at the above problem as an impression problem rather than an inking problem I probably projected that onto your reply.

Paul

rontxhou, you can’t tape up the roller supports on a proof press unless you have added roller bearers into the form itself; no indication that has been done here. Normally, the rollers are supported by the entire cylinder carriage, and if you try to tape the bed bearers you are just raising impression as well—and stressing all the bearings involved.

parallel_imp,

That makes complete sense. Thank you for the clarification.

I may be misreading the post, but I thought in danielheff’s third post he meant that he had 4pt of rule added to the side of the form acting as roller bearers. This is what I thought Peter was suggesting to tape.

I certainly would not be a proponent of taping the bed bearers, and agree with your assessment of the mechanics and consequences.

danielheff, a rule of thumb for cylinder press’, type
runs parallel to the form rollers. Your photos are so bad
I dont see how any one here could make a reasonable guess as to your ink issues. best james