I am having an uneven impression from side to side. It is packed evenly, I have put more packing in, taken some out… I am using a polymer plate. At first I thought it was something wrong with the plate, and I was about to remake it, but first I rotated it, and the same problem occurred.
The left side of the print is lighter than the right. When looking at the print, as you go up the left hand side, the impression gradually decreases. It is only on the left side, and I have no idea where to go from here. Any help is much appreciated.
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What kind of press are you printing with?
What are you using as a base? The base itself may be uneven….have you tried to adjust your ink keys? Does this happen with only this job?
there is a packing gauge on the delivery side of the press, you must have a certain thickness of packing or your impression won’t be even.
What is needed now is termed “make-ready”
You need to build up your base by applying layers of tissue increasing in size, starting at the lowest point, to the back of the forme.
Is this the first job you ran on this press? Is this job taking the entire chase or different from other jobs you’ve run before. Also, is this the first time you’ve used photopolymer or this base on this press?
If I understand the original post, the left side of your form prints light, regardless of plate orientation. While I too would look at the base, to make sure that nothing else is amiss, I put in all new packing and lockup either strips of new 6 pt rule across the chase (left to right or 4 or more pieces of known type high material (large cap M’s of metal type) and see how they perform If the problem is repeated, then you may have a problem with the press.
Not knowing the circumstances that this problem arose makes it difficult to know the source of the problem.
It is very possible that at some time in the past there was a major jam-up in the press. It may be that something interfered with the platen in the corner that is now low that actually twisted the platen. I have seen this one two other occasions. One was a home made frisket arm that interfered with the top left corner of the chase and bent the platen. The press was running wide open when it was put on impression. The crash was severe enough to shear the safety washer and bend the platen. There is no fix for this, you just have to attach a permanent make-ready to the platen to get successful prints.
If your base or furniture or even the chase is bowed it could be a problem. Make sure everything is 90 degrees.
Also try this:
remove the plate that is behind the left of the pump. With the power off remove any debris from inside, moving the press by hand a little at a time and feeling around with your hand pull out any paper residue. I’ve seen presses that have major paper build up inside.