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Discussion Starter · #1 ·
Hello everyone, the problem is the white color stops printing, at first everything is fine, then it starts printing with tiny lines. I changed the bumpers, cleaned the head already.
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As already explained in your other thread...this is ink starvation.
It happens when the printhead is consuming ink faster than it can be replenished.

If the obstruction is inside the printhead, recovery is difficult and may not last.
This is because there is no way to know if the ink buildup has been cleared completely or not.

For gravity fed systems (ie refillable carts), blocked breather holes can cause this issue too.
For pressurized ink systems, blocked pressure tubes/passages can also be the problem.
 

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Discussion Starter · #5 ·
As already explained in your other thread...this is ink starvation.
It happens when the printhead is consuming ink faster than it can be replenished.

If the obstruction is inside the printhead, recovery is difficult and may not last.
This is because there is no way to know if the ink buildup has been cleared completely or not.

For gravity fed systems (ie refillable carts), blocked breather holes can cause this issue too.
For pressurized ink systems, blocked pressure tubes/passages can also be the problem.
If the tubes are clogged, the inks would not be sucked into the cartridge using a syringe, as I understand it? I replaced the cartridges, cleaned the head, the cleaning solution passes through the nozzle without problems, the inks also passes through the cartridge without problems. But all the same, the white one does not print normally, I have no idea what it could be
 

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If the tubes are clogged, the inks would not be sucked into the cartridge using a syringe, as I understand it?
What do you think stops ink from coming out of the dampers when you unplug them?
There is a valve in there stopping the ink.
Clogs can act as valves too. Apply pressure and all looks good...but it is not.

cleaned the head, the cleaning solution passes through the nozzle without problems
The same here... you are applying pressure at the manifold. The printer does not do this.
Ink droplets are generated by tiny piezo actuators, just under the nozzle plate.
If there is no ink in the chamber, nothing will come out.
 

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Discussion Starter · #7 ·
What do you think stops ink from coming out of the dampers when you unplug them?
There is a valve in there stopping the ink.
Clogs can act as valves too. Apply pressure and all looks good...but it is not.


The same here... you are applying pressure at the manifold. The printer does not do this.
Ink droplets are generated by tiny piezo actuators, just under the nozzle plate.
If there is no ink in the chamber, nothing will come out.
So where did the pressure go? How to restore it?
 

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what type of printer is it? is the white ink actually gravity feed or is it cycling and refreshing constantly? On my printer its a loop in which the ink is being moved all the time and i can actually adjust the "print pressure" and the speed of the cycling.
 

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sorry, no idea if that is a gravity feed or cycling system printer. In my case all the colours are gravity feed and above the printer and the white is pump cycled and below the printhead. One thing which would increase feeding pressure is to raise the height of the white ink tank if that is possible at all.
 

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On my printer its a loop in which the ink is being moved all the time and i can actually adjust the "print pressure" and the speed of the cycling.
Your printer has a gravity fed printhead too.
Recirculating printheads used in high end industrial printers have two tubes per ink channel.
Here is an example of a two channel Epson S3200 recirculating printhead.
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The loop you mention happens before the dampers an it is for preventing ink separation in the supply tubes.
This is good to have, as well mixed ink will reduce clogging, but it is not the solution when the clog does happen.
Even purpose build DTG printers like the Epson F2100 or the Brother GTX can have the same issue.
The F2100 in the example has a pressurized ink system and white ink recirculation, but still a gravity fed printhead.
 

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uhm, i tend to disagree. Whilst you are probably correct in saying that the printhead itself (epson XP600 i think) is planned to operate as a gravity feed unit and can do so, I am able to CREATE and adjust enough pressure inside the feed system to make the printhead drip or not. According to the manufacturer, just before dripping is the correct setting. In my case (it is a purpose build dtg printer) gravity alone would not work and pull the ink out of the printhead back to the tank as the tank is below the level of the printhead. There is a whole bunch of settings i can adjust on the cycling system alone. Like cycle speed, cycle pressure and print pressure.
 

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I am able to CREATE and adjust enough pressure inside the feed system to make the printhead drip or not.
That's irrelevant.
The terminology is a bit confusing, but gravity fed printheads are non-circulating.
What is circulating in your printer is the ink inside the tubes. The ink inside the dampers and the printhead itself is not circulating.
The printhead pressure threshold of gravity fed printheads is too low, so what you are suggesting will make no difference.
 

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again, i would disagree but it really depends on the definition of things. The printhead itself is not circulating (the dampers are actually circulated) but i am still able to turn the printhead upside down and still get inc coming out of the nozzles as the whole circulation system is pressurized and the printhead itself is one of two outlets so will clearly respond to pressure from out of the circulation system. on the in-side you got the pump, on the out-side you got the printhead and the backflow into the tank. If the pressure/volume from the pump is smaller than the volume of the backflow, no pressure will be built up and the printhead would starv. But if the backflow volume is smaller than the pump volume, pressure will be built up in the system which has to go somewhere. As the only other exit is thru the printhead, this is where it will go. So in this case, not gravity reliant at all. That is why I can adjust the "print pressure" and also the "cycling pressure". When printing, the pressure needs to be higher as the printhead needs and uses ink. When in idle, you don't want any ink being pressed thru the printhead and the pressure setting has to be lower. The dampers seem not to be dampers in the conventional case. They are bigger and don't have a valve. They are only a big chamber divided by a screen and have an inflow on one side of the screen and two outflows on the other side/ bottom. One goes back to the tank and the bottom obviously goes to the printhead. Just to be clear, this is a dedicated DTF printer with two printheads. One is for white only on all 6 channels and the other is conventional gravity feed for colour.
 

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ok, so I will rephrase my initial question to caponeS. Is your system a pressurised system on which you can adjust the pressure? If you can, try increasing it in small increments. I did not realize that epson coined the word gravity feed but hey ones learn something every day. :)
 
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