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l26500 Prints don't line up for contour cut

Discussion in 'Hewlett Packard' started by Vital Designs, Aug 2, 2013.

  1. Vital Designs

    Vital Designs Vital Designs

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    Dalls, Texas
    I am going crazy over this issue.

    For example, I print 2" wide by 1" tall decals on 54" material and contour cut them. The decals on the outer edge of the material cut fine but the inner ones or offset along the y axis. It is a gradual transition along the x axis from good to offset back to good. It almost seams like the center of the material is bowed.

    I run the same job on a mimaki jv33 and it is spot on which rules out the cutter (FC8000). I have tried numerous materials from oracal, avery, briteline and 3M.

    Has anyone else run into this problem?

    Thanks
     
    Tags:
  2. P Wagner

    P Wagner Very Active Member

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    This is a known potential issue with HP Latex ink printers, when printing onto certain media products.

    The phenomenon is referred to as 'bowing' and is caused by media distortion when running through the curing zone of the printer. We have seen this on economy grade and some calendered vinyls more than higher grade medias. There are several approaches to resolving this:

    1. Lower the curing temperature for the media(s) in 7-10 degree increments to find the sweet spot for that media, where the ink is dry, and the bowing is not a problem.

    2. There is a printer firmware-based adjustment that can be turned on to correct for this effect called Straightness Optimization.

    3. Certain RIPs (Onyx Cut-Server for example) has a bowing adjustment that can be used to correct for the bowing effect.
     
  3. ProColorGraphics

    ProColorGraphics Very Active Member

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    Scene this many times! I am running a L26, but have a Summa S Class cutter. Along with Caldera, it will print a solid bar across the front of the print, which the cutter will read to help accommodate for the bowing. Cheap vinyl is definitely worse. The cheap paper makes the "bowing" worse. Normally, on the straightness optimization setting, you need to go negative with it.
     
  4. Vital Designs

    Vital Designs Vital Designs

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    Thanks guys, I assumed it had something to do with the heat. I normally just run most of these on the solvents but we are running small barcode decals and the latex does a slightly cleaner print between the small barcode lines.
     
  5. signdesigner1

    signdesigner1 Member

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    I've found that vinyl with at least a 90# paper liner will prevent bowing. Some of the more economical vinyls have a thinner 80-82# liner. Same vinyls different liner... Ask your supplier, it's usually listed somewhere.
     
  6. the graphics co

    the graphics co Active Member

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    The adjustment is called "straightness optimization" it is in the image quality menu. You have to adjust it for just about every different media you print, if you are doing contour cutting.

    The best way i have found to determine the adjustment is to print a 2" x 52" black bar across the media and lay a straight edge down across the edge. You can measure the gap or bow in the middle, it is usually tenth's of millimeters so it is difficult to get an accurate measurement. You need to make an incremental +/- adjustment maybe .5 at a time until you are perfectly straight with your test print. After that your contour cuts will be perfect for that media. Make a note or a list and keep it by the printer for future use and reference for your different media. It usually takes a good 20-30 minutes to get it dialed in for each media, but it is worth the time.
     
  7. HulkSmash

    HulkSmash Major Contributor

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    been printing on the latex machines for a long time.. never had an issue where they weren't lining up because of shrinkage.

    check your step size, and offset..
     
  8. eahicks

    eahicks Magna Cum Laude - School of Hard Knocks

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    Having this issue as well...I'll try dropping the cure heat a little. Just wasted a whole sheet of decals because the cuts don't line up. Normally, my contours are dead on (with Roland prints). Now it seems everything from the L260 is giving me trouble. And I used 4 point laser alignment.

    I thought something was off when I would cut a perfectly square graphic on the table and my straight edge looked like IT was bowed....now I know it was the print.
     
  9. Desert_Signs

    Desert_Signs Active Member

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    I don't think he's talking about panels lining up. The bow is too small for that to be an issue, and usually your panels line at what would be the outside edges of the material, if it was on a roll. Not the trailing/leading edge. On large jobs, you really don't notice it. It's millimeters.

    What he's talking about is contour cutting. It's especially noticeable on small decals with a thin border. You can have a perfect cut on the left and right edges of the media, and cut into the print in the middle. Sometimes even straightness optimization is a crapshoot. We finally gave up fighting with it and printed small stuff on 24" media. Worked fine that way.

    This was even an issue on the L25500. I argued with HP for a solid month years ago that it was a problem. They tried to convince me that the rail was bent, so they shipped another machine (we were beta testing the L25500). The new one did the same thing. They said it was out of their control and I didn't know what I was talking about or I was causing the error. I finally gave up. Lo and Behold a while later, a tech called me and said "Soo.... You should check out the firmware upgrade that was just released and look for straightness optimization...."
     
  10. GAC05

    GAC05 Major Contributor

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    For the updated poster;
    What software app are you using to set the registration marks and cut with?
    There is an option in the Cutting Master software that comes with Graphtec to add intermediate registration marks between the 4 corners to allow the cutter to compensate for bowing on long prints.
    Seems like it should work on the bowing the HP is causing even on smaller ganged contour cuts.


    wayne k
    guam usa
     
  11. Typestries

    Typestries Very Active Member

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    This is how we do it here. Adding intermediate marks helped a lot, esp since we have multiple printers and cutters running

    Still, there are some of the low cost vinyls with very light liners that move a lot under latex heat, and there will be sections of a print that don't line up well where the media moved excessively. We just avoid those medias.
     
  12. Bill Modzel

    Bill Modzel Active Member

    I normally run 30 - 36 inch material for smaller decals and have no problems. I just had a job that I printed on 27" General Formulations white static cling. I had to run 250 pcs on 8' long panels and had issues until I went to the intermediate registration marks the the guys above mentioned. It instantly solved the problem.

    A few weeks ago I was running a 12' long panel truck logo, all beveled and tuned up on Photoshop and placed in illustrator for printing and cutting. It was a major pain getting the stock to even track well enough to find the 4 corner reg marks. It was the first time I ever had contour cut issues when for some reason I remembered something about the multiple marks and used them for the first time. Bingo, problem solved. A bit more time consuming on the cutting but it saved my hours of frustration and wasted material.
     
  13. Split76

    Split76 Member

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    i have l260 + summa s2 140t, and i found that aslan dpf 09 vinyl works best for me. i can print 4000x1300mm and contour cutting is still very accurate. No need for any straightness optimization.
     
  14. eahicks

    eahicks Magna Cum Laude - School of Hard Knocks

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    I have had to switch vinyls. Now getting 3M with 90# liner and have so issues. Heat causes the thinner cheaper vinyls to warp and distort more due to the thinner liners.
     
  15. Timothy Mitchell

    Timothy Mitchell New Member

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    All Latex printers work by adjusting speed (pass mode), temperature (curing, specifically), and inkload (how much ink is set in both the restrictions and the global ink limits).

    What is happening is from too much heat, mainly curing, but possibly some drying temps as well (generally, drying isn't the culprit for deformations, curing is). You want to bring down the curing temperatures to bring the media under the media deformation point. The less expensive the SAV, the more likely to warp as a general rule of thumb. Cheap monomeric calendared is worse than polymeric is worse than a good cast, generally, and some SAV has better liners than others from a latex point of view.

    You can drop those curing temps while you print in the front panel. If the ink begins to get greasy, then you have to either increase temp or change to a slower pass mode. For temp sensitive SAV, I run 12pass, 200F (or less, I have gone as low as 185F) curing and 125F drying. Then I build a color preset around those two fixed settings: slower speed and low heat. Use the onboard spectro to build the transitions (lower the light inks to 15 and cut them off at around 55, you do not want too much light ink, Onyx will over-ink by default) and restrict the dark inks to around 75, look at the curve and find the sweet spot--remember, lower temps means lower inks). Then run a linearization and a global ink limit (advanced tab in Onyx for global). Link to an existing ICC, like the HP Permanent SAV. Now you have a low temp, slower speed, and a inkload that corresponds to the speed and temps. You'll find the SAV will be much easier to deal with this way, nice and flat and no warping and minimal deformation, and if you do run the straightness optimization, it will only need a small adjustment.

    Best,

    Timothy
     
  16. AF

    AF Active Member

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    The first 24 inches of a Latex print will have the most issues with deformation (bowing and lateral expansion). With cheap substrates pre feed a few feet of material before the print run so the first job will only have issues with straightness and not the funnel effect from the leading edge flaring. You should absolutely adjust your rip for dimensional changes in the media by printing a dimensional square and measuring the printed size. The size compensation will help your plotter quite a bit since some materials can move over a 1/4" in 3 feet while under the print head.
     
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