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MIMAKI JV33 PRINTS VINYL SHORTER THAN IT SHOULD

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Alex Espejo

New Member
Hey guys!
We’re going to change our printhead so I think it’s time to solve this problem.
When we print on vinyl, it prints shorter than it should. This wasn’t a problem since we didn’t need perfect length prints, so we reduced our cut path and it fitted correctly. Now that we print motorbikes, this is a very big problem, since it can print 1 cm shorter on a 2 meter print.
This doesn’t happen on paper. We printed some weeks ago a 160x310 square on paper, to see if it was problem of the printer or the cutting machine, and it was spotted on, no milimeter up, no milimeter down.
We tried with a brand new roll, rolled up, unrolled (to see if the tension caused this), a piece of vinyl without roll,… doesn’t matter what we do, it always prints shorter. We’ve also tried feed compensation and all the calibrations on the printer, but nothing solved this.
We’re using rasterlink, but I guess this isn’t a problem since paper is printed perfectly. The only solution I have found is to use this printer with onyx, so we can print the black lines and make the rip solve the error by itself.
Thanks, Alex
 
FrankW

FrankW

New Member
This is a design-related issue with roll printers, and depends on the thickness and nature of the media. Your printer prints unprecisely since been new, but you haven´t noticed it until now. A lot of RIP´s has functionality to compensate this. 1cm on a 2 meter print is nearby to the standard deviation of that printer.

In Rasterlink, you can do different scaling of width and length to compensate this.
 
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Alex Espejo

New Member
FrankW said:
This is a design-related issue with roll printers, and depends on the thickness and nature of the media. Your printer prints unprecisely since been new, but you haven´t noticed it until now. A lot of RIP´s has functionality to compensate this. 1cm on a 2 meter print is nearby to the standard deviation of that printer.

In Rasterlink, you can do different scaling of width and length to compensate this.
Click to expand...
Thanks for the answer, Frank.
My doubt is why vinyl is printed so short, if paper is printed perfectly.
Also, it’s not always the same deviation, some times it gets 0,6 cm, other time it can get 0,3,… (same length file and material)
 
FrankW

FrankW

New Member
Paper is much thinner as vinyl with liner, and have different characteristics. Is not so unusual.

On the other hand, a JV33 is a really old machine. Of course they can be some issues with pinch rollers or so. Not easy to estimate from distance.
 
N

netsol

Active Member
perhaps grit rollers don't grip vinyl the same way as paper? the did into roll paper more than the liner for vinyl?
did you clean pinch rollers with isopropyl?
there is no adjustment on my roland takeup reels, but, the mutoh has back tension adjustment that would account for this sort of thing
is the takeup on the mimaki free wheeling or does it have takeup tension adjustment?
 
Adam Vreeke

Adam Vreeke

Knows just enough to get in a lot of trouble..
Also depends if you are running heat, heat will expand the vinyl a little bit, but over a long print will make a difference.
 
A

Alex Espejo

New Member
I think there's some issue in any part of the printer, since I told you, it does a different error every time. I will check rollers and make all the calibrations to see if I can solve it. If not, I guess I will have to play with size compensation.
Thank you guys, will let you know how this finishes.
 
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netsol

Active Member
did you print 6 identical copies of a job & then verify that they are EXACTLY the same size?

if all the same size you can compensate

if there is variation it could be as simple as slippage, (but certainly a different sort of problem)
 
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netsol

Active Member
the reaason i said print 6, print 2 first thing in the morning,
2 at lunchtime & 2 at end of day after the printer has been through it's paces all day
 
N

netsol

Active Member
whatever length makes the difference easy to see.
i am wondering if
(1) you stretch the vinyl a little
(2) pinch rollers/grit rollers slip
(3) electronic failiure (capacitor or resistor changing critical value effecting those adjustments that effect the feed
(4) pinch rollers aren't dropping cleanly

lets start by deciding if this happens as you work the machine, is it a "thermal runaway" problem?
 
A

Alex Espejo

New Member
netsol said:
whatever length makes the difference easy to see.
i am wondering if
(1) you stretch the vinyl a little
(2) pinch rollers/grit rollers slip
(3) electronic failiure (capacitor or resistor changing critical value effecting those adjustments that effect the feed
(4) pinch rollers aren't dropping cleanly

lets start by deciding if this happens as you work the machine, is it a "thermal runaway" problem?
Click to expand...
as it doesn’t happen when printing on paper, I guess it’s not an electronic failure. tomorrow I will print the same job multiple times as you said me, to check if it changes the length. the thing will be to know what of the possibilities you said, it’s the one causing the problem
 
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