1st unit bad register

Hi i work on 1994 4 color heidelberg speedmaster sm74. I have problem with the register on the first (Black)unit. At the botom of the papper the register is good but slowly stretches out at the top. I chenged the blanket and the underblanket, by the book 2.3mm together with blanket! Grippers are cleaned. Maybe presure between blanket and plate cilynder. Is it possible to adjust that?Any idea?

 

you May need to change the packing under the plate, you need to use packing with a lower gauge to shrink the image

 

Hopefully your not putting packing under the plate, if you are I would remove it. Also, pressure between plate and blanket can be adjusted, however it is very difficult to adjust it accurately without proper tools. This you may need to call a Heidelberg tech for. I would also check for the obvious first. Cam follwers, dirty grippers, clean bearers. You may need to have your infeed tuned.

 

No im not putting packing under the plate. Black color seems to be good the other 3 colors are inside 1mm. I mesure printed papper of the black color with the plate and that is good. Other 3 colors are inside. Here is a picture from the register left side up and right side up.

 

are you printing with long grain paper? It is not uncommon for this and other register issues to encountered when printing paper short grain. Does this happen on all stocks? If it is in fact happening when your printing long grain and all your grippers and pressures check out i too would be looking at the infeed as exheidmech mentioned. Not sure if your vintage press is equipped with a compensator on the infeed but if so and it isn't trashed from running with it on you could try to correct that way.
On a final note i need to ask if your press has a perfecter after the first unit? If so my guess would be your problem just might lie there.

 

Its grippers problem. How to adjust them?