Tri-loc issue

[kingscreen]

We have run into an interesting issue with Tri-loc that we can't seem to wrap our heads around.
On a 3 color print, 2 colors were dead on but the 3rd color was off by nearly a 1/2"!  It appeared to be off in an exact horizontal 1/2".

What would cause this?  How do we correct it? 

edit: We tried reburning the screen and using a different print head.  Same issue remains.  Lines up perfectly on the light table/carrier sheet.

[Printficient]

I would ensure a level and plumb press first.  Next check for a consistent off contact.  Next check for a firm grip machine arm to tri lock platen,  Next check for over aggressive screen clamps.  Last check for screen warp.

[Dottonedan]

I don't remember if you've got an I-Image but if you do, when this happens, it's almost always human error where someone believes it's been pushed all the way back under and it hasn't. I've heard people say they loaded 6 screens for one job and one would be off. They swear and truly believed all were locked in place correctly but it can be deceiving at times.

When it's off at an angle, if on the I-Image,  The error is almost surely a lock in error where it's not been touching all three points.

A 3rd area is the ability to move a screen down on an individual case (in the printer control Y axis). People do this sometimes when something was provided too high from the art dept. If it's been moved, they need to remember to set it back to 0.000

It can also be on press when locking it in. (be sure to hold all screens down on the screen and pull into the locking points at the time of locking down with air. Otherwise, it can jump out by contact with non flat screens.

Film alignment of course is the other human error factor.

Some people swear the machine printed it lower or higher, but it can't print 6 usable, registered images and move one of them out of place. It can happen, but it would have had to of been moved by mistake in the art. Again, accidental human error.

[jvanick]

a few questions to help troubleshoot:

- if you stack the films on the light table, are all lining up?

- if you measure from the edge of the frame to the reg marks, are they at the exact same distance?

- are you trying to do some kind of ganged images on a single sheet of film?

- at the press, are you sure that you're hitting the same areas on the trilock platen?  When we first started using the trilock every once in a while we'd raise the press and the screen would be on TOP of the stops... it would seem like it was in the right position, but it wasn't.

[whitewater]

when you lock the screen down does it shift a hair?

[Squeegie]

We had an issue with one head a few years ago.  I found that the frame was contacting the clamp head before the stop blocks.  I used the micros to pull the head away from the triloc stops further and it reggies correctly now.

[kingscreen]

Dan - No I-Image here.  I'm beginning to think it's a warped screen but we tried 2 so that's what's left me scratching my head.  I checked the screen that lined up almost perfect on each print head and it landed in the same place.  When I did the same for the screen that was out of wack, it was out of wack the same on all the other print heads.  That makes me think it was the screen itself.  I'm just not sure how it would have gotten so out of wack.

Films line up perfectly on the light table.   No ganged sheet.  One film per screen.  Clamps have plenty of breathing room from the stop blocks.
It didn't shift a hair, it was a full 1/2" to one side.  That's the confusing part.  If it were a hard pull from a clamp, it would be up/down.  And I can't see it moving that much.

[dirkdiggler]

Scott, check the spring loaded pins on the frame that's mounted to the exposure unit.  We have had them get stuck and your screens will not be in the correct position when you expose.

[dirkdiggler]

one more thing, this happened to me too, glue from the tape that holds down the frame on exposure unit leaked out and stopped screen from being spring loaded into place.

[JBLUE]

Scott, check the spring loaded pins on the frame that's mounted to the exposure unit.  We have had them get stuck and your screens will not be in the correct position when you expose.

Had this happen before. Somehow one of the guys got tape wedged in there and caused it to stick every once and a while.

[kingscreen]

So....no issues now.  Strange but seems to have been a fluke.