designjet problem

[Tom_Designjet]

Hi guys,

My HP z6100 has a serious problem. The prints, darker areas, have a "wave" pattern along the length of the print visible at certain angles. A guy from HP told it is caused by the media , as it doesn't have hard enough surface or hard enough coating. So far i noticed it is directly connected to pinch rollers When you look at them the pinch rollers have S-shape pattern on them. That pattern is exactly what appears on the prints. S-shape is exactly the place on pinchrollers that do not pinch/touch the media surface.

So far i tested two medias, both matte, from different manufactures. Both have identical problem. Unfortunately, i don't know of any other media that's suitable for my work, and one of them comes from renowned german manufacturer and the effect applies to their other products too.

When i removed the rollers, the problem disappeard, though of course it causes other problems so you can't print without them.

Here are the pictures - shape of pinchwheels:

and (look at the black area closely)

Any suggestions appreciated.

Bests,
Tom

 

[artbot]

what it sounds like is pinch roller tracks. get a cloth and some light solvent. not sure what HP makes it's wheels out of. but you can start with a glass cleaner and get tougher with other harsher fluids if that's not doing it but keep an eye out while experimenting.

put some solvent or cleaner on a rag. and force it into the pinch zone between the top and bottom roller (drop the rollers if they have a lifting mechanism). while forcing the rag into the nip, advance the wheels with a front cover function (feed media, etc.). this will force the wheels to spin against the rag. those little wheels are impregnated with coating and dirt. and they are pressing all that stuff into the surface of your media. do that first and get back.

this takes a while. do a single wheel and then do a test print observing that wheel position to make sure you are getting a good result. before moving all the way across the machine.

 

[Billct2]

Have you tried the HP forums?
http://forums11.itrc.hp.com/service/forums/home.do

 

[Tom_Designjet]

I cleaned the rollers with isopropyl. After 30min of isopropyl bath i cleaned them with microfibre cloth. Then waited a day so the residues evaporate.

Got the same effect exactly.

I'm running out of ideas guys

 

[artbot]

if they are clean, then your printing space might be too humid or too warm. keep in mind you are using aqueous media. that media is coated with a thin layer of synthetic gelatin.
if that coating is softened in any way it will allow the pinch rollers to emboss themselves into the media. also, pinch rollers can alter the charge at contact causing the ink to behave differently along those tracks.

i've got a lot of experience with pinch roller tracks because i print on veneer and aluminum, etc. NEVER do i use a stock substrate. so i've seen this in a lot of situations while trying to develop my coatings and such.

 

[Tom_Designjet]

I tried the humidity between 45-55 and different temperatures. Changes to these factors had no effect on the intensity of the pattern. So i guess it has more to do with the quality or specifics of the manufacturing process than the environment. At least in this case.

I bought a roll of cheapest coated paper and...it has no such problems. Cheapest of the cheapest, i assumed the coating can't be more awful Yet it worked. Interesting, isn't it ?

 

[Tom_Designjet]

I withdraw what i said about the cheapest paper The problem is still there, though less visible.