Registration on part of the sheet off??

[Cameron]

Hey everyone, Ive got a really odd problem I was hoping someone could try and help out with.. we are running some business cards on our 4 color GTO.. the sheet size is 12.5 x 19.. press handles up to 14x20, and the stock is just a regular 12 gloss tango.
There are 21 up I think, 3 rows of cards.. the lead edge row of cards are registered perfect... the trail edge row of cards are registered perfect.. but the center row of cards jsut wont register.. the magenta is off.. how is this happening?? We've tried running the grain the opposite way..weve tried flipping the file upside down.. we tried lowering the tack of the ink... my press operator has been running a press for 20 years on this same press for at least 10... we're at a losss....

Wondering if anyone has any suggestions or has run into something like this before...

I should specify that with the registration off in the center row it makes those cards look aweful.. like 3d without the glasses..

 

[Al Ferrari]

Assuming you normally do not have this problem:

Is it possible that there if a packing issue on the magenta unit (plate or blanket) on this job?

Also, if you are film based, does the problem show up on your film based proof?

I you are CTP, have you tried a new Magenta plate?

Have you tried a different stock?

Al

 

[Kaoticor]

Which direction is the register off?

 

[HPC]

Sure sounds like a packing problem, a quick way to check is to put a finger print on lead an back edges of the blanket, have the press print that sheet, then measure the gap to make sure its not under or over packed. Max image for us is 16 5/8 so my gap should be 3/8 (its a web with a 17 inch sheet)

 

[Cameron]

Thanks for the replys everyone, first thing this morning the operator had a look and repacked the magenta head.. everything stayed as it was.. then tried the cyan head and that was the issue. The magenta stood out but because of the cyan coverage it was hard to tell.. it was actually an imperfection in the cyan blanket. We had run a few sets of 4 color envelopes a few jobs prior on that press.

very odd the way it appeared.. first time seeing it do something like that but in the end all solved and pointing me in the direction of the packing was what got us on the right track.. thanks everyone!!!!!

 

[Al Ferrari]

On a 4 color press, packing should be one the early things to investigate when troubleshooting image fit problems. Hang a sign with that message near the press.

Al

 

[Cameron]

Thanks Al, youre right.. we've got our eye out for now and forever about that one! Just dumb luck i guess that its never appeared quite like that before. Thanks again!!