Modifying cartridges

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Before any print can be made, the cartridge needs to be modified. While ordinary ink does slightly bind the powder, alcohol or binder does a way better job. Simply using a syringe to drain the cartridge will get rid of a lot of most of the ink, but this step needs to be repeated dozens of time before the concentration of ink is low enough (you’d be surprised to see how strong the ink is). A better way is to crack open the cartridge, properly flush the cartridge and completely replace the content.

what will you need:

  • Small screwdrivers
  • A lot of paper to clean up any spillage
  • A sink with running water
  • An empty syringe to drain most of the ink.
  • A syringe with the binder you want to use
  • A cartridge with the sticker still on (modifying a used cartridge without damaging it is very hard)

The binder can be one of a few things. I use an official binder that is made in combination with the powder. Another popular binder is alcohol, such as vodka or sake. In these instructions the standard binder with a tiny amount of red ink from a cartridge is used.

During the entire process of modifying the cartridge, the sticker covering the nozzles should stay in place. This protects the nozzles and between the breaking, the flushing and the refilling, nozzles might fail. Keeping the sticker in place protects the nozzles as much as possible. Also do everything on a layer of newspaper or above a sink, with paper and a wet disposable towel present. Usually you will not really spill any ink, but when you do, you will permanently ruin the thing being hit.

First peel the sticker covering the labyrinth from the top of the cartridge. Two holes will become visible. Use a syringe to drain as much ink as possible from both of the holes. Try to get the needle everywhere in the cartridge, the sponge will practically stop the ink from migrating in the cartridge. All the ink you remove here is ink you don’t have to worry about later. If you have a long needle, be careful right above the cartridge’s contacts. This is where the filter is that connects the reservoir to the nozzles. Poking a hole here will probably ruin the cartridge.

Crack open the cartridge. The top of the cartridge has been merged with the base of the cartridge. This seal is not really meant to be broken, but in order to replace the cartridge’s content, it needs to go. Breaking it open without any damage is impossible, but try and damage the cartridge as little as possible, especially the back, where it connects with the carrier. The seal is facing down (towards the nozzles), so this is the direction you will need to break the cartridge open. Use a small flat headed screwdriver wedged in the seal. Angle it around 30° down to get the screwdriver under the seal. Carefully work your way around the cartridge, avoiding the back. Don’t go too deep in one pass and don’t try and lever the top off. Instead, slowly go around and when you feel that the seal is broken enough, go all the way through with the screwdriver (all around). Repeat this going from the front to the back. When the entire seal is gone, you should be able to simply peel of the to without using any force.

Take the cartridge to the sink because the next few steps will drain the remaining ink. Use something sharp to grip the sponge. Then, above the sink with a puddle of water to catch any ink, pull the sponge out. This does require some force, the sponge has a tight fit. When the sponge is completely out, drop it in the water and let water from a tap run over it. Also flush the cartridge’s reservoir under the tap until the water comes out clean. Squeeze the sponge until no more ink comes from it, squeeze any remaining water from the sponge. Then push the sponge back in the reservoir (look at the indents for the orientation).

Tape the lid back on the cartridge with a single piece of tape. Then use the filled syringe to fill the cartridge again. 10-15ml should be enough. With the cartridge full, tape of the rest of the edges of the cartridge. There should be one path to a hole which needs to stay clear. This path is the labyrinth and it prevents the cartridge from creating a vacuum when printing, while also preventing the cartridge from drying out.

Lastly, before using the cartridge, remove the sticker. Everything is now ready to use. The cartridge is flushed, but channels are still filled with the original ink. It will take some printing before this ink is gone.

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  1. Hello all!

    I have been working to build one of these over the past months; SLOWLY am I chugging forward. I made a video ( of the cartridge ink replacement that hopefully will fill people in.


    I had tried several different methods for removing the ink from the cartridges including a full tear down. I found the easiest was to get a beaker with mL measurement and draw the ink out with a needle.

    On average I was able to get 10mL out of the 20mL out of the cartridge per cartridge. I measured the removal because I noticed that if the cartridges were overfilled when putting the alcohol binder in it caused “strange” spray patterns to emerge when running tests.

    Also, I made sure to order a needle that was “too short” so that I didn’t have to worry about puncturing through the sponge into the spray nozzle.

  2. Hello,I had much trouble with C6602,it can not work,no ink was sprayed out.Do you have datasheet of C6602, and how to control it? If you have ,please help me.My you very much.

  3. Hello! Which kind of binder had you chosen to replace ink ? I found that some kinds of binder can’t be jetted from the nozzles.Maybe their viscosity is too high???May you introduce your binder?Thanks very much!

  4. Hello,
    If I use another cartridge with higher DPI and connect the same HP C6602 connection, it is possible?
    Thanks so much!

    • No, Most printheads use a different control system than the C6602 used. How a printhead is controlled really depends on the year it was made. Older heads have simpler control systems than newer heads.

    • With the C6602 it might be hard. The heads are quite big and really low res. In principle you could do it with a clear, black, cyan, magenta and yellow cartridge, but half of those you’ll need to make yourself. This would give a 15cm wide printhead. Bigger printheads are narrower and higher resolution, some with multiple colors. But a lot of work needs to be done before the average maker can use them.

      Short answer, yes, but with the 6602 it is difficult.

  5. The length of life really depends on just luck. I had cartridges last not even one print, and the cartridge I printed most has already printed over 100 hours, and is still working. It has even been sitting idle for months on end.

    The best way to clean clogged nozzles is to suck ink through them. You could get tools for this, but I didn’t ever have them. What I did was get a cup of water and get near a sink, get some water in my mouth, and suck some ink through the nozzles with my mouth. Then rinse my mouth and the cartridge. It is not the best tasting solution but it has worked miracles for me.

    If the nozzles are broken, you simply need to replace the cartridge.

    • @peter

      I found that it takes ~13 cartridges if you want to spray the entire build area; however, I have found that over time the alcohol does affect the spray pattern. I have found that about two days is the life expectancy of an idle cartridge.

      I have *NOT* experimented with the storage of the cartridge and I am just starting now. I just bought a ton of cartridges. I am assuming that the alcohol affects the sponge somehow or evaporates out the top holes (shrug).

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