Stripes printing on Web Offset

[Alois Senefelder]

Hello jsnKiefer,


What you are seeing are - Cyiinder Gear Marks - these marks are related to the Cyl Gears Teeth Pitch Circles

To eliminate this problem - the Blanket/Plate Cylinders Pressures need to be Reset by a Qualified Press Engineer !


Regards, Alois

[jsnkiefer]

Well, now I would ask;

What is the undercut on the plate cylinder?
What is the undercut on the blanket cylinder?
Are you running .008 plates?
What is the total of the blanket thickness and packing?

Just because the book that came with the press says to do something a certain way does not mean you should do it. Goss has, over the years, dispensed some pretty bad packing requirements.

Thanks, Dan.

From our GM: Plate is .008” undercut. Blankets undercut .081”. Yes we are running .008” plates. Blankets are packed to .084” total blanket plus packing.

[Joe Duffy]

Well, now I would ask;

What is the undercut on the plate cylinder?
What is the undercut on the blanket cylinder?
Are you running .008 plates?
What is the total of the blanket thickness and packing?

Just because the book that came with the press says to do something a certain way does not mean you should do it. Goss has, over the years, dispensed some pretty bad packing requirements.

And if it has been moved or cylinders redone, newspapers typicall would run a .0065 plate plate to save money, could be your .008 plate is thicker than what it undersut for. Also, what is the true thickness of the plate, are you sure they are .008?

[EGWebguy]

Sorry, I think it is a pre-press issue, but not of your own doing. We had this exact issue a number of years ago on our Timson
T32 and we found out is was bad plates. From the manufacturer. We washed the plate and using a loupe found that the coating was coming off the plates either during processing or after our fountain solution was applied. Try ordering different plates or a different manufacturer of the plates.

[BeauchampT]

If it is all the units displaying this problem, it has to be a universal variable - you can pretty much rule out things such as roller settings, etc. (unlikely that they are all set equally poorly).

Ink also is a little less likely (usually cheap ink will vary in quality colour to colour). That said, have you changed ink recently? If you have, use a lithographic window test to see if it is a tight tolerance - it might be a poor ink/water window is allowing some other weaknesses of the press to show up....

I would lean towards fountain solution or plates - even if things are up to spec, doesn't mean something hasn't changed. Are you a multipress facility?? Has anyone on anther press seen same problem???