Mimaki JV33 bidirectional printing - DROP.POScorrect

[OLE]

I'm struggling these days to set bidirectional printing on Mimaki JV33.
There is an option DROP. POScorrection in Maintenance menu,
but every time test is printed values get changed. This adjustment
consists of eight patterns and every pattern controls different print mode.
My idea is to make fine tuning with specific pattern until I reach top quality.

Can anybody tell me which pattern is responsible for which resolution?

 

[OLE]

Any ideas?

 

[SightLine]

Where did you read or get the idea that each of the 8 rows or patterns on the Drop Position Correction test draw is each for a different print mode?

I've never read that on anything. I could be wrong but I have been under the impressions that each of the 8 rows are for each of the 8 rows of nozzles on the printhead and the values are essentially just altering the firing rate for each row to adjust for different thicknesses of media (or a different viscosity of ink) that all feed at slightly different rates.

The manual states that the Drop Position Correction adjustment is all for Bi-directional printing. It states "When the thickness of the media, the height of the head, or the type of ink used is changed, follow the steps below and adjust the ink drop position for Bi-directional (Bi) printing to print properly". Then it walks you through running the Drop Position Correction.

You also have not given anyone any idea of what the problem is that you are experiencing so no one can really give you any help. You could also download the service manual and go through some of the more in depth adjustments in the service menus.

 

[OLE]

Must be that those eight patterns are somehow related to different print modes, the question is how,
or which pattern is responsible for which resolution(i.e., pattern No.(?) for 540x1080dpi(fast), pattern No.(?) for720x1440 dpi...)
Do you have JV33 or CJV30? Please try to print this test and pay attention to the carriage speed, every pattern
would be printed in different mode. Also, if your claim is true that eight patterns are related to eight nozzle rows,
then there have to be different colored patterns not only black.
Even if you perfectly finish all adjustments in service mode, you would still not have adjusted bi-directional printing,
these eight patterns are kind of "fine-tuning".
I'm just trying to get maximum from the machine, it's not about any problem. Sometimes is very hard to do this
setting, because of just a little change in media height(on the print heater) can give you wrong readings.

 

[Solventinkjet]

The drop pos. correct patterns are related to the nozzles and not the resolutions. When an ink drop leaves the head while printing bi-directional, it is going to be moving in the direction that the head is. This means that when the print head is moving to the right, the firing timing will be different when it comes back to the left. All drop position correct does is adjust the timing of the nozzle firing so that the head knows when to fire so that it can hit the same spot on the material after it changes direction. This is why when the adjustment is off, it looks like you are seeing double because the your head is essentially printing cross eyed.

The reason there aren't any other colors on the test patterns is because the spacing of the nozzles is so precise that they can just use the black set of nozzles as a base point and then add the amount of space between the nozzles mathematically. It's just easier to see black than yellow.

 

[OLE]

Ok, but I don't understand why there must be eight patterns,
why is not enough to print and read just one pattern and all other values
can be calculated by machine?

 

[StopSignGraphics]

It's been a while since I had to adjust mine but if I remember correctly the patterns are variations with slight adjustments.

In other words, I think, it was you picked the best of the 8 test patterns. Plugged in the corresponding value and repeated until it was aligned properly.


~Chris

 

[Solventinkjet]

Ok, but I don't understand why there must be eight patterns,
why is not enough to print and read just one pattern and all other values
can be calculated by machine?

You are correct. For the most part when you run this alignment you will notice that every other pattern has the same, or close to the same, value. If they are extremely different, something is either wrong or the distance between the head and media is inconsistent(buckling). They just do eight to make sure there are no subtle differences. The main factors that affect the pattern are, media thickness (which can also throw your alignment off if there is buckling in the media), how old your motor is, environmental factors like humidity and temperature, ink type and the state of your encoder strip. Basically anything that can change how the ink falls out of the print head and when it actually hits the media.

 

[97GTB]

You need to do all 8 patterns not just the best. There re 8 patterns as they are for different head speeds, i.e.. STD and FAST print and also they are for the
different dot sizes. Whatever the value of the patterns is this is the number you change the value on the display. i.e.. pattern 1 = -5.4 you change the display
to -5.4, do not add or subtract from the existing value.

If once all these adjustments have been done and print quality is still poor, you may need to do the service alignments, as the DropPOS Correct is a customer
adjustment. Hope this helps, if not check out the JV33 bible by Artbot.

 

[OLE]

@97GTB:
Thank you for your answer, I think you are completely right! Every pattern represents different print mode,
it is not the same pattern just repeated eight times.

THERE IS ONLY ONE QUESTION LEFT UNANSWERED:
Which pattern controls which print mode(i.e., which one is responsible for 720x1080dpi, VD, Fast)?

 

[Solventinkjet]

The drop position correct alignment in the service mode allows you to select the motor speed and resolution to align. You can go through and align each mode and that will set a base line for the user mode drop position correct. Once the service mode alignments are done, run the user alignment and you should be good to go.