Please take a look at the attached picture

[mustafade]

lawnmore effect is a bit tricky to explain but I'll try. When the head travels from left to right, it fires the inks and the ink droplets land on the media. The ink does not land perfectly straight with the media though because of the momentum from the head traveling. Now, the same thing happens when the head travels from right to left only this time the momentum is in the opposite direction which means the droplets from the second pass are slightly different from the ones in the first pass. So the two pass are in essence opposite of each other. Kinda like the lines one get in your lawn after mowing it.

I hope that's a good enough description... I'm still on my first coffee.

I find that certain colours are always problematic no matter how well tuned my machine is. When faced with the issue, I just run the job in uni-mode and that usually takes care of the problem.

That was a good explanation. Makes perfect sense but I am not certain if explains my issue I am having.
Thanks Sticky Signs,

 

[Jemmings]

Feed Comp

It takes a large change in the feed comp to see any difference. Try moving in incremates of 30.

 

[h82loose]

How is the printer connected to the rip? Network. I had an issue lately where the switch was causing a data problem. It looked like ink starvation. Realy odd but it never paused. Tried everything (damps,head, feed adj, alignments) until I put a new network switch in.

 

[mustafade]

How is the printer connected to the rip? Network. I had an issue lately where the switch was causing a data problem. It looked like ink starvation. Realy odd but it never paused. Tried everything (damps,head, feed adj, alignments) until I put a new network switch in.

It is hard wired via USB 2.0 which really the only way to connect JV33's to the rip.
It is a good way of thinking thou if it was a network printer.

 

[Sticky Signs]

I agree, I don't think that's the cause of your problem but i would run a uni test just to rule it out. Plus if you get good results in uni, you can at least keep your printer running while trying to find the real issue.
Good luck

 

[HK Dude]

lawnmore effect is a bit tricky to explain but I'll try. When the head travels from left to right, it fires the inks and the ink droplets land on the media. The ink does not land perfectly straight with the media though because of the momentum from the head traveling. Now, the same thing happens when the head travels from right to left only this time the momentum is in the opposite direction which means the droplets from the second pass are slightly different from the ones in the first pass. So the two pass are in essence opposite of each other. Kinda like the lines one get in your lawn after mowing it.

I hope that's a good enough description... I'm still on my first coffee.

I find that certain colours are always problematic no matter how well tuned my machine is. When faced with the issue, I just run the job in uni-mode and that usually takes care of the problem.

Love Sticky Signs' "Lawnmore effect"... because the print does look like a freshly mow lawn. This is my 1st post on 101 and I am looking to solve the "same" problem. The photo is a bit small but it is similar to what I am getting when I am running the Mutoh 1604 in 2 pass (bi-direction). Again, the photo is a bit small, but it looks like chromatic banding (light band and then a dark band). Should that not be the case, please accept my apologies.

I have been doing some reading on this and I think it has to do with the way the ink is sprayed. When the head travels from say left to right, the ink that hits the media goes like this in order (on the 1604): KCMY... When it comes back going right to left, the firing goes like this: YMCK having Y landing first. This being so, it means that the passes will be finished in an alternated K and Y as the final run.

On my prints, we only get this effect when the colour darkens... deep blue and brown... all the way to black. Light colour does not seemed to be as obvious. When we run more passes to the print, this Chromatic Banding effect gets smaller and smaller until we eventually don't see it with the naked eyes.

As Sticky Signs pointed out, uni-direction does solve the problem we have with Chromatic Banding. So this somewhat confirms that Chromatic Banding does occur based on the order in which the ink is being lay. And as mentioned, if this helps with the uni, at least we can have a print ready for the client. (sorry, this message might be 3.5 year late)

To solve this problem, maybe you need to increase the passes.

To help with this problem, there are a few things that we have done that does ease the problem to a certain extend:
1) Try turning the preheat down (or even off) before the media gets printed. This will allow the ink to saturate more before it gets dried. Crank up the heater (dryer) when the media leaves the printing platform so that you don't ended up with a wet print going into the collecting roller.
2) Limitation to the above would be the material itself. We run North American, European and Chinese media and not all material are created equal. Some will take up ink better but cannot stand the heat, other will stand up to the head but hates the ink. So you will need to test the material.

The reason why I am very interested in this because I am looking for a way to modify the print head configuration so that we can print with 2 passes. Will start another thread about this.

There we go. My 1st post. Heart is pumping as there are so many expert here.

Cheers !!