CRAZY banding out of nowhere...

[Circleville Signs]

Anyone have any idea what would cause this type of banding? Started about 3 print jobs ago, gets worse as the job progresses. This was an 8 foot banner, and this is the last 12-14" of it.

I've cleaned the encoder strip, and I'm getting a near 100% nozzle check.

Mutoh 1304.

 

[genericname]

Worse as the print progresses? Maybe a messed up damper or weak seal? Could be that once it refreshes, there's enough ink to drop a good test pattern, but little else.

I'd run solid bands of all your ink colours for a few inches each, and see where the drop-off starts.

 

[rjssigns]

Ummm...does banding run the same direction of the scrim? We had that twice. Once from an odd banner material with huge "peaks and valleys". The second time the designer actually put pinstripes in the background that lined up perfectly with the scrim. Thought the job was ruined. He just laughed and said: "Perfect, just what I wanted".

 

[Circleville Signs]

No - its on several different materials. Adjusting heat upwards helps SOME but doesn't eliminate it. I will try solid colors and see what happens.

 

[rjssigns]

Feed Calibration or servo motor giving up the ghost? If that isn't it I'm out of ideas.

 

[ellsmako]

When it starts doing it, do a nozzle check. if its good then you dampers etc are fine. Look like a cyan or yellow head. I do not see it in the pink.

 

[Gino]

Does it do it with any color or just certain ones ??

We've had a few colors over the years.... no matter what we did or material, the color wouldn't print well. Had to change the color slightly to fool the software into printing properly.

 

[Circleville Signs]

Doing a test print right now, 4"x10" blocks of CMYK, spread across the length of the print area.

I'll post results shortly. This printer is REALLY starting to **** me off

 

[Circleville Signs]

OK - here is what I just printed. As you can see, in the first picture the banding is not very prevalent at all. The 2nd picture is a closeup of the blue/magenta of the block of 4 colors that would be coming out of the printer closest to the capping station. As you can see, about 4 inches in, there is the start of some light vertical banding - but it is NOTHING like what I was getting in the OP. That was horizontal banding, and BAD horizontal banding.

Any thoughts?

 

[Circleville Signs]

Here's one more photo from the original job that I posted. You can see that the banding didn't appear gradually - it just "BLAM", was there....

 

[Gino]

Your ink is not coming out evenly. Somewhere, either in the lines, capping or nozzles something is blocking or hampering an even flow. Possible a suction of the C and/or M would be the place to start.

 

[Circleville Signs]

Wouldn't that affect my nozzle checks, and start from the very beginning of a job?

 

[MikePro]

air bubble in the cyan ink supply? might be worth flushing the ink line, but i would double-check that your dampers are seated properly and the connections are snug before doing so.

 

[Gino]

Wouldn't that affect my nozzle checks, and start from the very beginning of a job?

Not if something is minutely rolling around in there, so to speak. It could happen randomly. If you have definite patterns, then I'd be a little more concerned.

 

[sfr table hockey]

Right when the banding starts, if you stop the print and do a nozzle test print what do you get?

 

[rjssigns]

Sounds like starvation since it prints fine then F's up. And I tend to agree with Gino after my experience with cheap inks. You could have a pigment chunk rattling around.

 

[Circleville Signs]

Sp, pull and re-seat the dampers - or just switch out the yellow and cyan dampers and see what happens?

 

[vagrant]

had that happen before, it would randomly start banding in the middle of a print- we were using some 3rd party inks and we think it was just a bad batch. for a quick fix though- we printed on high quality and slowed the head speed down to about 800 instead of 1000. if we happened to notice it start banding, we would pause the machine which makes the head go back to the capping station and suck more ink, it gives the ink flow a chance to catch back up. then un-pause and let it roll... it eventually stopped doing it which makes me think it was just a bad batch of ink. hasn't really happened since we started shaking up the ink cartridges before putting them in.
hope this helps!

 

[Perks]

What about the dither setting. This is suppose to eliminate certain kinds of banding in the original file.

 

[Gino]

It seems to be a random happening.