Thick Paper on HP Latex not staying flat on Print Bed?

[Krittah]

I'm printing Magic PhotoArt230 paper (230gsm) on a HP Latex 115 and starting to have some print trouble which wasn't there at first. Been printing this paper for a few months now with no problems and using the HP Heavy Matte Paper print profile. Now I'm starting to get drag marks from the print head hitting the paper in the middle of the print zone as well as some grain in this spot. The paper is definitely bubbling up a little in this spot, so I know this is what I need to fix.

Things I've tried:
1. Cloned the Preset.
2. Reduced heat to lowest setting 140º (it was at 158º).
3. Ran test and reduced ink to 80%
4. Calibrated, but had 2 head crashes in a row while doing this, so gave up on that!
5. Added take up reel.
6. Printed with a result of about 98-99% perfect quality. Which I was happy enough with at the time, but still want to get it 100% perfect moving forward.

After all that, I still have a 1 inch spot in the middle that just won't lay flat. For that finally print, 53x36" there were only two spots with a very light 1/8th" long head strike mark and light grain running the length of the print.

Also, the suction holes seem to be clear, but what is the correct way to check and clear them?

I should note... I've also had some new trouble printing HP Premium Poster Paper with profile that comes with it. Once again, it use to print great, but now some prints are off. Mostly grainy solid colors, as well as line edges and text printing blurry. Not sure if this is related, so I'm mentioning it.

I'm hoping someone here has some tips on how to get this fixed. I'm about 9 months into HP Latex printing, so plenty left to learn.

 

[balstestrat]

You didn't list it so add more vacuum.

 

[Gino]

What's the tension like on the feed side ??

 

[P Wagner]

If the contact is occurring in the print zone (with the carriage), then increasing the vacuum would be correct.

The other possibility is that the media is touching the roof of the curing unit causing ink smears. Look into the cure unit while the ink is curing to see if the paper is 'tenting' and causing contact with the top of the cure unit. Increasing front tension through the use of the take-up reel can help with this.

 

[rjssigns]

What is the humidity in the shop? In high humidity media will go out of spec for moisture. This can lead to buckling when heated.

 

[Krittah]

Thanks y'all. I did add some vacuum (forgot to say that), from 15 to 20 I believe, but sounds like I need to revisit that and increase it more. The contact is definitely happening with the carriage, I can see it through the view window.
I also thought humidity might be a contributing factor since I'm in New Orleans and our current weather has the AC not running all the time. Humidity was about 67% in house yesterday when problem was at its worse. I did turn the AC on to get the humidity back into the mid 50% range, which is when I got my better print.

 

[balstestrat]

20 is nothing. Try 50 next time.

 

[netsol]

are you clogging the fan/impeller that provides the vacuum?
the rolands look like a "dust bunny" when you open the fan enclosure,

 

[Ronderick]

Following. I have a HP 115 and just purchased some photo paper to print for the first time. Krittah what take up reel did you add? Did you install it yourself? Thanks

 

[Krittah]

Following. I have a HP 115 and just purchased some photo paper to print for the first time. Krittah what take up reel did you add? Did you install it yourself? Thanks

I purchased the take up reel along with the 115 at the same time, it's an optional addition. I plan on printing a lot of wallpaper, so the take up reel seemed necessary.

 

[Krittah]

Thanks for all the suggestions. I'm currently thinking it's the humidity in my house, since the problems really started with the weather change.

Things I'm doing:
• I've changed the HVAC thermostat settings to keep it running more constantly.
• Getting a humidity detector for the print room that syncs to my phone so I'll get alerts.
• Took plastic wrap off paper rolls and waiting a day or so in hopes paper dries out and is still useable.
• Considering a dehumidifier just for the print room if HVAC doesn't do the job.
• May add more vacuum if this doesn't work, or maybe just add some anyway!

I'll follow up when I have more info on what's working or not.

 

[Shakerit]

Did you fixed it? I have been struggling with this same issue with my latex 115, have tried 3 different SAV and keeps buckling in the middle of the printing area, i have tried adding vacuum, less tension and of course less temperature, nothing seems to work, my printer is in a closed room at 26celsius and about 50% humidity

 

[george paris]

Have the same issue with my HP335. I was told by a HP tech rep to use the take up reel. It uses too much paper when doing one or two prints at a time. He also recommended getting a couple of spring clamps, and add 8 oz weights to them, to put in the middle of the roll where the problems seem to be. (talk about hi tech!). I print mostly on hp Prime Matte GP and it runs fine. It has a satin like finish, which works for the type of jobs I do.
Otherwise, when I have to do the odd print only small job, I use Lexjet's cheapo paper and sit like a mook in front of the machine and hold the middle of the paper to keep it flat! Decidedly low tech solution! Good luck!

 

[RMarshall]

I've always had issues running 54in rolls of paper on our 560.
After countless times trying to get it to work I now just use a 42in roll of Sihl 3686 and outsource anything larger (which isn't very often).

 

[JamesLam]

Regardless of roll width we have found that we have only had issues in the first foot of printing. And it was due to either carriage scuffs or rubbing on the curing unit. Our solution was to feed more stock through or to unload at the end of each day so the roll doesn't take on a tighter curl on the leading edge.