Mimaki stretching imges?

[Ninjaman65]

Hello. Here at my shop we do a lot of illuminated signs. When it comes to digitally printing for an illuminated sign I print the graphic on a translucent 3M material. I then print the same graphic on an optically clear 3M material. Once they are both dry I apply the optically clear on top of the translucent. This is to help with color consistency when the sign illuminates (although it turns out to be a bit darker when not lit).

Anyway, recently I have noticed that the two images do not line up when I try to apply them one on top of the other. Almost as if one of the graphics got "stretched" or "shrunk". On my most recent project (a rectangle graphic with words inside it), if I line up one side of the graphic, the other side is completely off. The height is fine, but the width is off.

The Mimaki JV3 160SP we have uses solvent ink and the optically clear material is pretty thin. I think maybe the solvent ink is causing the optically clear material to shrink a bit?

Also, I am running Flexi 8 Pro with Production Manager.

Any help or insight would be greatly appreciated. Thanks!

 

[Graphics2u]

I can't imagine trying to print the same image on two different materials and having them be identical! Your printers feed calibrations would have to be adjusted perfectly for each material. Why not do a double print on the translucent vinyl? I don't print on this but i've seen others say that is what they do.

 

[marcsitkin]

If the difference is 90 degrees to the direction of travel of the print head, it's due to either to slippage of one of the materials or a compensation in the feed calibration needed for one material. Check the manual for how to do this

 

[J Hill Designs]

welcome from cali

ya, what they said.

Plus, if you lay the print on clear down first, then the print on translucent, your prints will look less dark when unlit, but add the needed oversaturation when backlit...

 

[SightLine]

Only thing I can think is pretty much all materials "stretch" a little and and feed a little different and the 2 different materials stretch at slightly different rates and due to slightly different liner thicknesses feed at slightly different rates. I also run backlits but I just set Flexi on the Driver Options button to Ink Layers to 2 times and set a dry time between passes of 1 second. That gives me the much deeper ink saturation needed for it to look halfway decent when lit and of course does have the same less effect of making the image much darker when not lit.

 

[MikePro]

+1 to double white trans. printing... eliminate the headache and just align two identical images.

 

[Letterbox Mike]

I know you didn't solicit this response but I'm going to offer it up anyway... You're doing your backlit prints backwards and causing a lot more work for yourself for no apparent reason. If you're doing a clear layer and a trans. layer, the clear layer goes under the trans. layer, not on top. This preserves color appearance during the daytime hours but greatly enhances the saturation of the color at night. Actually, you may consider printing two layers on ink on the clear layer so you've got even more ink density. Printing a clear layer on top of a trans. layer is accomplishing exactly the same thing as just double-printing the translucent layer, but it's costing you twice as much media and headache getting the two lined up. Plus, putting the clear on the bottom is a little bit more forgiving, if your registration is off a tiny bit it's not nearly as noticeable.

Regarding the stretched prints, how far off are they? 1/8"? 1/16"? 1/2"? How are you applying them? By hand, wet application, dry through a laminator?

 

[Morph1]

you all waste your time and money on printing on 2 medias for backlit signs...., the trick is to print on single clear media x 2 ink layers callibrated with linearization mode, it only works in flexi 7.6, we run flexi 7.6 for all back lit media and 8.6 for opaque prints, for some dumb reason in flexi 8.6 they took that crucial component away !!!!!

and in regards to your media stretch be sure you either print both on cast or both on calendered media, and as other say it also could be the media compensation , we recently had a similar problem where a print would not fit on to a routered to shape substrate, the print was longer by 3/8" we did recallibrate media comp and it fit perfect.

Hope this helps,

CHeers !!!

 

[Rooster]

Heat and take up roller tension will stretch the material as it travel over the printer platen. The heat and tension stretch the material as it prints and then when it cools it winds up shorter.

Reducing heat and/or take up roller tension will help to reduce this issue of varying print length. I'll eliminate the take up roller entirely with some jobs that require a high degree of accuracy in panel fit.

The suggestion above assumes that you're running the correct feed calibration for each material of course.