Vutek flatbed wrinkling on long runs

[N.E.]

We had a Vutek QS3200 for 4 years and replaced it with a GS3250LX last year. In all that time I have not found a way to resolve a media wrinkling issue. No matter what rolled media it is I get a wave on the supply side that gets worse as it prints (see attached photo). Anything over 18' - 20' and the wrinkles start to move up to the print area and I get a head strike. I haven't been too concerned since most prints don't exceed that length. However now I have a job that consists of 17 50 foot tiles and I need to find a way to prevent the wrinkling. I've tried 100% vacuum, 80% 60% even 20%. Lower actually seems to make it worse. I've tried adjusting the tension on the supply roll as well to no effect.

Anyone have any suggestions?

TIA

 

[WYLDGFI]

EFI calls it the Smiley Face....and thats a crock of BS. We have had a QS for a number of years and like you have the same issues with long runs of vinyl. Thats why we have roll-to-roll printers for a majority of our jobs.
Even using the front takeups does not help with our experience. We've run from the table...from the input roll...no luck. It really does suck. EFI has not given us any help either for this situation. I attempted to put Blue Painters tape on the bar and make the left right and centers Thicker to avoid having total pressure across the material, but not sure that helped much as we still had that issue 18-20 ft into a 25 ft print. What material are you trying to print to?

 

[JoshLoring]

I don't know ANYTHING about these printers... But general logic would say the feed/takeup is bowing causing the smiley.
Any way to strengthen the feed and takeup by adding more center support? Cross brace?
Ideas ideas... Big wide roll = bow - arch = no smiley.

Had this problem with banners on a takeup at one point... We bungied the takeup to another machine to add tension to the center and all was well.

 

[jasonx]

Looks like the vacuum is leaking on the sides causing the material to slip a bit gradually.

Have you done a test with say 1370mm wide material to see if it gives you the same problem?

 

[WYLDGFI]

According to the field techs from EFI....getting rid of the smiley causes other problems. The feed bar is actually 2.875 OD Stainless with an air bladder in it...similar to most large format printers like HP and others. It can bend with heavy rolls especially 2.8-3.2 meter ones....102-126in....
We have seen this same problem though when just running lightweight 10oz banner off a 64in roll on our UV Press. Its not limited to just the wider rolls.
N.E. Give EFI tech support a call again....Bob or Alejandro are both really good on the phone....some of the other people are so/so.

 

[Jack Knight1979]

I thought these big boy printers were bullet proof. Looks like every printer made has it's quarks regardless of price. I'm sorry to see this happening to you guys.

 

[WYLDGFI]

A lot of it is the belt and how it interacts with the roll material.

 

[HaroldDesign]

It's been a while since I ran one, but I do recall maximizing the feed and take-up tension helping quite a bit.

 

[nashvillesigns]

even center taping it to a empty core doesn't help? ( my feeling is the actual core is "Warping" since its cardboard (total guess but if its 10-16 long..) and that creates slack in the middle, which, creates the tunnel big enough to wave a hot dog through...

 

[Jack Knight1979]

Can you get a piece of aluminum pipe to run down the center of the take up core to bulk it up?

 

[jasonx]

My HP has a support shaft that slides inside the core and onto the shaft. Would stop any bowing problems you'd have if its the core giving.

 

[N.E.]

Thanks for all the replies. The supply and take up are solid bars with an air bladder inside that inflates to put tension on the cores. I ended up running the job on my HP latex.

 

[WYLDGFI]

Good call...my QS sucks for running long jobs on banner media. Narrower rolls of pressure sensitive vinyl etc work much better.

 

[IAmTheMan]

There is one of two ways I have found to alleviate the smiley face. The multiroll tripod you got with your printer, jack it up in the middle of the full width roll, that should take some bow out of the roll. You may need to raise it as you print, make sure its not pushing up too far on the core, or you may damage your media.
Another way is to physically modify your media infeed, its not permanent unless you want it to be (so you can take it off before the service guys get there ). You have got to make it work in such a way that it is fed over the top of a smaller roll before going underneath the pinch roller. I have used a 3.4M 2" aluminum pipe held by two fixtures on either side of the rear operator control (looks like a U and the aluminum pipe goes inside the U on either side.

 

[Letterbox Mike]

There is one of two ways I have found to alleviate the smiley face. The multiroll tripod you got with your printer, jack it up in the middle of the full width roll, that should take some bow out of the roll. You may need to raise it as you print, make sure its not pushing up too far on the core, or you may damage your media.
Another way is to physically modify your media infeed, its not permanent unless you want it to be (so you can take it off before the service guys get there ). You have got to make it work in such a way that it is fed over the top of a smaller roll before going underneath the pinch roller. I have used a 3.4M 2" aluminum pipe held by two fixtures on either side of the rear operator control (looks like a U and the aluminum pipe goes inside the U on either side.

Could you post a picture of this setup and how the media is webbed through it? We have the same problem on our CET and I'm wondering if this would be an option for us as well.

 

[Signarama Jockey]

I have an EFI Pro 16h 64" UV Flatbed printer that runs media off of a reel in the back, and I have the same problem - it gives me anxiety running anything longer than 8 feet. We had to run a 20 foot banner today, I I found myself staring off into space, hearing Helicopters with the Doors playing in the background.

I've put a lot of thought into this problem. These are the sources of the problem that could be plausible:

Media. Either it’s too humid or too dry, or too stiff or too loose. Something about the media, or the rolls the media is on is causing it to deform as it goes into the machine.

Dancer bar or feed roller. One of the bars might be putting pressure on one side or the other, or on both sides too much. It may be warped or not level or might distribute tension unevenly when it triggers the feed roller to spool more media out.

Pinch Roller. The roll that flattens the media to the conveyor belt might be irregular somehow.

Belt. The belt may have some quality to it that pulls or stretches the media

Vacuum. The vacuum holes might be aligned in such a way that the media is being pulled into the center of the belt? Or perhaps the center is being pulled before the edges, causing the ripple?

A combination of the above factors.

There is a distinct possibility that I am missing something, but these are the obvious components that could go wrong.

 

[Signarama Jockey]

Could it be the media? I’m inclined to say no. It doesn’t matter if I run poster paper, vinyl, banner material or canvas, the same issue pops up with the same pattern. It happens on 63”, 54” and even 24” media. I can switch the roll between printers and have problems on the flatbed, but not the other printer. No, I’m pretty confident we can rule the media out.

Could it be the dancer bar? I doubt it. When this issue first popped up, my instinct was to say that it was due to me mis-loading the media. I thought that the dancer bar and the feed roller were trying to enforce the right way to feed the material - essentially a fight between the bar and my mistake. But, then I spooled out media onto the floor, so that if I was feeding the media incorrectly, it would still go in flat, just trend off at an angle (but still be flat). Even with zero tension on the media feeding into the machine, the wrinkle still happened. So, again, I'm leaning towards no on the dancer bar being the problem.

Could it be the pinch roller? The old strip of leather we have as a subcontractor and installer took an interest in my investigation, and he was sure that the problem was the pinch roller being the problem. He pointed out (correctly) that the metal roller is not a perfect cylinder; it has a warble to it. His proposal was that we take the pinch roller to a machine shop and lathe it down to be a perfect roller, but I don't think that would help. Considering that I have media in with the pinch roller up, and gotten the same distortion in the media. The pinch roller just flattens the wrinkles down so that the excess material bulges in the familiar smiley face pattern (until it ultimately builds up too much and it passes under the roller altogether). If the bulges aren’t flattened, the heads are more likely to strike or catch and fault out the print - so if anything the pinch roller helps keep the problem at bay as long as it can.

Could it be the belt? Okay, so this is interesting. Let me ask you - have you got buildup on your belt? I know I usually do. I print a lot of full bleed boards, and a strip of ink will buildup along the edge of there these boards normally seat. This buildup leaves a noticeable ridge in my roll media. It's not high enough to cause a head strike, but it is noticeably taller, and it just so coincides with where one corner of my smiley face is. Could just be a correlation, but it gets me thinking. After my media comes off the roll, under the dancer bar and up, it meets the belt, and takes a 90 degree turn into the machine. The way I see it, the media that is going over the ridge is traveling farther than the media that doesn't. That makes sense, right? I mean, if this wasn't a 63" roll and instead it was a bunch of individual strips, and they were all running paralell into the machine at the same rate, wouldn't the strip that has to go up an additional fraction of an inch be traveling farther than the one next to it that just goes immediately onto the flat part of the table? So, if this is the case, if the media that is going up the ridge is traveling farther, then it is pulling the media that isn't. It would be a very small distortion, that would increasingly become more pronounced, and it would look exactly like what I see. The middle moving slower than the sides.

Earlier today, I ran an 8 foot banner through the machine and it had terrible wrinkles. I cleaned off the belt and re-ran the banner while I was typing this last bit. The banner survived this time. Not sure how definitive that is, but it's something.