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How to install an external waste ink tank on a Canon MP780 (or MP760)

Discussion in 'Canon InkJet Printers' started by ghwellsjr, Jan 14, 2010.

  1. Jan 14, 2010
    ghwellsjr

    ghwellsjr Print Addict Platinum Printer Member

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    WARNING: Please do not attempt this procedure--read post #6 before continuing.

    It is very easy to cut a hole in just the right location to extend the two tubes coming out of the purge pump on the MP780 or MP760 printers. You can raise the printer up on blocks and place a shallow jar, bowl or other container to receive the waste ink. You can do this as an alternative to taking the printer apart and replacing the waste ink pads or you can do both. You don't have to wait until the printer tells you that the waste ink is full, you can do it at any time. When I did it, I had already cleaned the inside of the printer and so it was not a messy job but if you do it without taking your printer apart after it has been used for a long time, you will encounter some messy ink which you will need to clean up before you can finish.

    The trick to doing this job is knowing exactly where to make the hole. Fortunately, there is a clear indication of this on the bottom of the printer. You will need a couple short lengths (2.5 inches) of vinyl tubing 5/16"OD x 3/16"ID which you can get at most hardware stores.

    Here is a picture of the purge unit (out of a printer, in a ziplock bag to contain the mess):

    [​IMG]

    And here is a closeup of the tubes we want to connect to:

    [​IMG]

    Before starting this task, you should remove the cartridges, do a deep head cleaning followed by a nozzle check and repeat until nothing prints. Then remove the print head and unplug the printer with the print head still in the center of the printer. Now tape the scanner unit down to the front door of the printer and tape the sides of the scanner to the sides of the printer. You don't want the scanner to fall open while you are doing this work. Also remove the paper tray at the bottom of the printer.

    When you are ready to start, lay the printer on its back so that the bottom of the printer is upright before you. Look along the right side of the printer for this image:

    [​IMG]

    The flat dimple in the above image corresponds to a dome shaped dimple on the inside of the printer shown here (it's partially hidden by a rectangular wall):

    [​IMG]

    The faint outlined rectangular area above the dimple is where we want to cut a hole.

    Drill three starter holes of a convenient size just above the dimple but try not to go as far right as I did. Make sure your drill bit does not go through the plastic by more than a half inch or you may drill into the bottom of the purge unit. You will encounter black ink as soon as you break through. Clean as much of this up with cottom swabs as soon as you can.

    [​IMG]

    Use a box cutter or other sturdy sharp instrument to widen the hole into a rectangle. You are trying to match a rectangular hole in the waste ink pad that is raised about an eighth of an inch above the bottom of the printer as shown here:

    [​IMG]

    And here is what the enlarged hole looks like:

    [​IMG]

    Here is the same view with a light shining into the hole so that you can see the ends of the two tubes that need to be extended. You can also see some of the padding material:

    [​IMG]

    The 3/16"ID tubing is too small to fit on the purge tubes so you will need to expand it slightly by running hot water across one end and prying open the hole using long nosed pliers. It needs to be visibly enlarged. When it is the proper size, you can stick the tubes on to the existing tubes and they will stay with a snug fit. However, I used some Automotive GOOP adhesive to glue them to the bottom of the printer so they cannot fall out. Here's what it looks like after installing the tubes:

    [​IMG]

    I took the printer apart to see how the tubes fit on the purge unit's tubes:

    [​IMG]

    The final product after restoring the printer to its proper orientation and putting it on blocks:

    [​IMG]

    There is a similar 2x4 under the left side of the printer but I found that I also needed a third 2x4 under the front to keep the paper tray from falling on the bowl when it was pulled out.
  2. Jan 14, 2010
    pharmacist

    pharmacist Print Addict Platinum Printer Member

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    Hi ghwellsjr,

    fantastic post. Sadly I already sold my good old MP780 (which still has a much better scanner compared to my latest MX850 printer). Is it possible to redirect the tubing with some extra tubes side-way ?
  3. Jan 15, 2010
    ghwellsjr

    ghwellsjr Print Addict Platinum Printer Member

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    I suppose you could but not without taking the printer apart. Websnail mentioned somewhere on his site that the purge pumps in the Canon printers are not very powerful so you really cannot expect it to pump the waste ink a long distance or up to a higher level to avoid raising the printer up on blocks. You can read this thread to see our discussion on this topic.
  4. Jan 15, 2010
    pharmacist

    pharmacist Print Addict Platinum Printer Member

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    Maybe it is possible to isolate the area where the purging tubes come out and to use a syringe to suck out the ink at regular intervals to clean that particular area, since the pump system is much weaker than that in Epson printers.
  5. Jan 15, 2010
    ghwellsjr

    ghwellsjr Print Addict Platinum Printer Member

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    Are you suggesting taking apart the printer and putting a tube in the well where the ink is deposited and the other end comes out somewhere so that you could periodically suck the ink out? I suppose you could do that but once you learn how to take the printer apart, I think you would simply replace the pads. It's not that hard. Here is how to do it.
  6. Jan 21, 2010
    ghwellsjr

    ghwellsjr Print Addict Platinum Printer Member

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    I've always said, My best ideas are the ones that haven't been tried out yet.

    Extending the purge tubes under the printer to deposit the waste ink in a container was one of my best ideas, until I tried it out. It worked great for a while but tonight when I decided to put some Windex on the purge pads, I discovered that the purge system was clogged, it would not suck out that Windex and I could clearly see underneath the printer that nothing was coming out. Real bummer!!

    I could see a deposit of dried ink at the bottom of the two extended purge tubes (see the last picture in the first post), so I tried to clean them out with a cotton swab and then a piece of wire shoved up the openings, but still no waste ink flow and no clean purge pads.

    Finally, I pushed a syringe onto the ends of the extended purge tubes and sucked on them. Eventually, I was able to restore flow.

    However, this is clearly no longer a good idea. I plan to eventually put the original bottom back on the printer and abandon this external waste ink disposal scheme.

    So what went wrong? I think maybe the exposure of the extended tubes to ambient air dried some ink inside the tubes, maybe not just on the bottom end but further up inside the printer.

    So is there a way to avoid this problem but still have the external waste ink tank? I thought about putting some Windex in the shallow bowl so that the bottoms of the tubes would be slightly submerged but this would require constant attention.

    I called my local Canon repair shop to get a price on the waste pads and they quoted less than $7. Even when I was taking apart my printers, I realized how easy it was and how easy it would be to replace the pads (as long as I didn't have to clean them). So that's my plan and I do not recommend anyone cutting a hole in the bottom of their Canon printer to install an external waste tank.
  7. Jan 21, 2010
    Nifty

    Nifty Printer Master Administrator

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    The beauty of invention at work! I still love this thread and hope the group can come together to find a resolution. ghwellsjr, maybe you might want to edit your first post and simply add a "Please see the update here before trying this" and link that text to your post above? I'd hate to see someone gung ho about this try it out and then get to this post and think "OH MAN!" :)
  8. Jan 21, 2010
    ghwellsjr

    ghwellsjr Print Addict Platinum Printer Member

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    I already posted a WARNING at the beginning of the first post. Are you saying I should tone it down?
  9. Jan 21, 2010
    Nifty

    Nifty Printer Master Administrator

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    Oh, sorry, I hadn't noticed you had already posted your note at the top. No worries.


    Your submersion idea is interesting and may be worth a try just long enough to determine if the issue is ambient air.

    If the problem is ambient air, I wonder if having the tubes enter into a sealed plastic bag (that could expand as ink entered) would work?

    Any chance there was an odd reaction between the tubing you used and the Windex or something like that?

    I would think the # of potential issues would be limited since the tubes are draining vertically vs. if you had tried to extend them vertically or something else.
  10. Jan 22, 2010
    ghwellsjr

    ghwellsjr Print Addict Platinum Printer Member

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    Websnail has a plastic bag as one of his options for an external waste tank. Now I can see the advantage of using one. I think I will try my idea of submerging the ends of the tubes in Windex and see if that eliminates the problem just to learn if it is really the ink drying out in the tubing.

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