2 unit prints longer on non-op side of 2 color press

I have a 2 color press and unit #2 prints longer than unit #1 but only on the non-operator side...the marks on the operator side are dead on...there is an adjustment on each tower to move the master cylinder & inking unit forward towards the delivery or backwards towards the feeder (on the non-op side only), which would also require re-paralleling the plate to blanket strip. I can also change the blanket to impression pressure parallel adjustment on the non-op side for either tower....

So my question is, which adjustment is more likely to make unit 2 print shorter on the non-op side, and if so which direction should I make the move???

And I am certain it is not plate stretch and almost 99% sure it is not fan out as it is consistently the same regardless of plates or paper...

 

what kind of press? blanket thickness....,underpack...,plates....... etc??

 

Any press mechanics out there that want to input?

Toko R2SL (very similar to a Ryobi 3302), blankets are Fuji 0.067", mylar packing .040 (0.020 x2) for total thickness of 0.107 per manufacturer specs, running Mitsubishi Silver Digiplates 8 mil imaged on a DPX 5080 CTP (internal drum)...

First, the plates are not stretching I have confirmed this, Secondly, it is not a packing or blanket issue as the image is not longer or shorter over the entire width of the sheet but only on the non-operator side. The adjustment I am referring to is a factory adjustment that is seldom done again, usually only after moving/reinstalling a press or when doing a complete press rebuild, and "targets" or zeros in both units so all 4 corners of the sheet are perfectly in register...

On the Toko (if I recall the 3302 is the same) there are 4 bolts on each unit (2 on non-op 2 on op side) that keep the units (master cylinder & ink train) locked in position to the blanket cylinder...if you loosen 2 on the non-op side and 1 on the op-side there is an adjustment on the non-op side that will allow the non-op side of each unit to move independently of the blanket cylinder either towards the feeder or the delivery...I have made the move several times and re-adjusted pressures (parallel changes with each move) but I still can't get all 4 corners to line up...to be specific all the marks on the operator side I can get dead on perfect, and can get the marks on the non-op side close but the non-op side gripper corner in about 0.5mm too high for unit 2 (closet to the delivery) indicating to me that the non-op side is printing longer than the operator side...I have noticed that changing the blanket to impressions parallel adjustment does affect this, but the factory adjustment doesn't seem to affect it regardless of the direction I move it. I tried small moves first, then more extreme moves and couldn't tell any change but it should have changed and drastically, but it does affect plate to blanket pressure on non op side...I can probably get it to fit using the blanket to impression parallel adjustment, but it was parallel to start with so to make it fit that way is throwing off my parallel which is not the correct way and I don't like doing it that way...any press mechanics out there what to chime in???

Also for you T-head users out there, there is a similar adjustment on a T-head used to target the T-head to the parent press, very similar to what I am talking about here, I even re-read the old T-51 install instructions on target to make sure I remembered the moves correctly and applied that to the Toko but still no success...

There is no information about this in my Toko service manuals, I don't even remember it being in the Ryobi service manuals now that I think about it...

 

Have you tried a set of metal plates with targets? To be honest poly plates can be all over the place. They are pretty good but not 100% IMO. So before you drive yourself crazy on press I'd be sure to rule out poly plates first. BTW stretch them suckers to fit if you can. I do!

 

I would not trust laser printer printed poly plates with your situation, before you touch any factory adjustments- have 2 real plates made and try them first.

 

It is not the plates, I have tried metal plates with same results, I run 8 mil polyester of a DPX 5080 CTP with internal drum...It is a press issue of the two printing units not lining up correctly, if it was plates the results would vary from press run to press run...

And no we don't use laser printer plates, but thanks for the input guys...

 

This is not something you can explain in text. This is something that has to be done first hand. You need to re parallel your blanket cylinder to your impression cylinder