showing print head lines

[petepaz]

i am printing a large set of decals with vp540
and the art has a black halftone
the first couple where good now i am getting lines
it is not printing even(i think)
i tried doing a cleaning
i am printing on oracal 3164 vinyl

 

[KR3signguy]

lawnmower effect?
Flush & clean again!

 

[petepaz]

thanks

 

[Velocity]

Do you have the specific profile for that vinyl? if not you may need to do some trials to get the best profile for the material. Also... you dont shut down the main power on your printer do you?

 

[KR3signguy]

He said the first few were ok, so the profile should be fine. It seems one color is dropping out. Most likely a clogged line or air.

 

[Velocity]

Granted. So are the lines appearing during a run where the first few are good and it progressively gets worse or is it now when you print you always get the lines?

 

[petepaz]

no the lines stay the same
it just looks like it is printing in rows

 

[KR3signguy]

hows it going?
Does a prime remedy the issue?
Also make sure your printing bi directional.

 

[petepaz]

alright i did a med and a power cleaning and it is back on track
here's a thought why didn't i try looking in the manuel
it said when this happens try multiple cleanings and if it doesn't work you have to clean the heads
turns out my tech guy is doing an install so i couldn't get a hold of him

 

[ChiknNutz]

That's commonly called "banding" and can also be adjusted with your Media Feed Calibration, which typically needs to be adjusted with variations in material thickness. Have you done an Environmental Match today?

 

[ChiknNutz]

Hmmm, I've NEVER performed a medium or powerful cleaning on my machine in the 2+ years I've had it....only the normal ones. If that doesn't work, then I'll perform a manual cleaning.

 

[Velocity]

Do you shut down your main power at all? I used to do this thinking power surges could destroy my precious printer but Roland printers cycle every so often to keep the print head from clogging and it cost me dearly. Not trying to scare you but this caused my printer to band like that and it took a pair of new heads to fix. Panel power is ok to shut off but main power should be left on. Previous to that I had some broken pins that goin into the bladders that caused air to enter the bladders causing the same kind of problem.

 

[KR3signguy]

We keep our heads as clean as possible, the darn things are too expensive to replace $1200 per. Gotta keep the flow going!

 

[iSign]

Also make sure your printing bi directional.

why is that?
isn't it true that even in microscopic amounts, a drop of ink travels the direction of the head as it falls to the vinyl... so in bi-directional, half your drops are misaligned to the right & half to the left (in microscopically small amounts of course)...

...if in some prints, evidence of this phenomenon shows up as lines, then uni-directional may be better. Based on the first few printing well, I wouldn't suspect this inhis case, but I just wondered how bi-directional would be a preference?

 

[ChiknNutz]

True, unidirectional will produce the absolute best print quality, but at glacial speeds

 

[KR3signguy]

it depends on the picoliter, head hight, media stepping and positioning of the printheads. Some machines are straight forward, some are staggard, some move
C/M/Y/K/LC/LM and LM/LC/K/Y/M/C on the second pass with 24 heads.
most machines should print the same way to human eye it's just uni takes longer.

 

[iSign]

...and all that somehow explains why you would say "make sure your printing bi directional"?

 

[KR3signguy]

The laydown of ink seems to staggar on the droplets "depending on head hight" more on bi which slightly fills in the bands at least it seems to on ours.
Bi is the preference mainly because of speed but the stepping of the machine changes & that may be a factor in banding. I guess it depends on how the individual printer handles this.