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  1. #1
    3D Printer God(dess)
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    Exclamation Cube 3 - Leveling your print head

    Today was a real wake-up call on this little printer.
    A little history: We're talking about my little white printer that has been my workhorse for the last year-plus.
    This printer was a warranted replacement (#2!) and has run 10's or pounds of filament (high usage would be in the neighborhood of cartridge/week).
    Most of my printing has been from the left side and single filament.

    This printer has always lain over the left side little red wiper. Annoying, but something I hadn't wanted to deal with.
    I have printed dual colors on this printer in the past with mixed results.
    The worst part of printing dual colors is the fact that it is so hard to find two nozzles that are exactly the same elevation.
    If you get lucky enough to get to this point, which I once did, the biggest problem is color bleed when the wipers don't clean the nozzle enough.
    This was quite some time ago. However, I knew it worked.

    In the recent development efforts in making printable nozzle housings, apparently I broke something.
    When testing the twist-on caps for nozzles, for some reason the black heat-shield was popping off.
    The only thing I could attribute this too was thermal expansion of the plastic.
    This cap-popping issue was tested several times before I abandoned this way of making nozzle housings.

    Yesterday I was converting the Infinity Rinse cartridge to the B2B solution. I was able to maintain all the seals in this cartridge.
    So today I went looking for a pair of matching nozzles. No dice! They were off by nearly a millimeter consistently.
    Of course, this required investigation. Minutes later, the printer was in pieces looking to level the print head.

    I found a means to reliably pop off the heat shield, the black cover that the nozzles stick through.
    There are two small square holes in the housing that can fit a small screw driver and pry against the housing.
    This is from the back of the system. The image is trying to show the hole I am referring to:

    x1.PNG

    Lay the printer on its left side with the front facing you. Put the build plate in place.

    #1 The heat-shield cover must be removed to get to the leveling screws, WHICH ARE NOT THE TWO SET SCREWS!
    These two larger screws require a short version of a 2mm or 5/64" hex wrench. I had to trim a hex wrench shorter to fit.
    The small set screws require a .050" or 1.25mm hex drive.

    #2 Insert a couple of the B2B nozzle assemblies that you plan to keep paired up. Or stock, if you are still running stock.
    These should fully seat with a little spring tension behind the. Meaning, they shouldn't wiggle.

    #3 Loosen the two small set screws located at the brass plastic inserts. These should be proud when beginning the adjustment operations.

    #4 Loosen the two silver screws where the blue goo is. Once loose, the print head should be able to twist a little. You will find very little vertical play but quite a bit of rotational play.

    #5 Push the build plate up to the pair of nozzles. You are trying to set them level with the build plate. Back off the build plate and snug up the two larger screws. Pull up on (to the left) the white plastic housing while snugging the 2 screws. Recheck level.

    #6 Now that the print head is somewhat stable, and you know which nozzle is closer to the build plate, adjust the smaller set screw only on the side that is closest to the build plate. Just until it touches the rail carriage. Meaning, at the moment you feel resistance, stop.

    #7 Loosen again the two larger screws (1/8-1/4 turn should suffice). Tip the print head a little on the nozzle displaying a gap. Snug up the screws again. recheck level... repeat from #5 until you think you can't get it any better.

    ... loop breakout;
    #8 Tighten the larger screws. This is what is holding the print head level. Do not over-tighten, obviously, but they need some reasonable level of tightness.

    #9 Clean any filament that may have built up in the heat shield where the nozzles stick through. Replace the heat shield carefully making sure it snaps into place. If all is well, the nozzles should still be at the appropriate level. If not, the heat shield is deflecting one of the nozzles. You can try flipping the heat shield 180 degrees to see if this resolves the issue. Check for plastic buildup on the outside of the nozzle... whatever may be causing the variation. if nothing obvious, it is the heat shield pushing the nozzle against the spring in the nozzle housing. If this persists, you need to compensate for successful 2-color printing. Go back to #1 and note the variation you want to make to account for the heat shield deflection/offset.

    #10 If you got everything level, confirm by gapping the nozzles. if the nozzles are not perfectly level, make your prominent side the one closer to the build plate. Having two nozzles tends to add a new "snag" for your print to fail on. That is what makes this process so touchy.





    It was at #9 for the 3rd time that I was noticing I had a problem. For some reason, the black sleeve that holds the small side fans would move on one side only. Allowing this to change also changed my levelness significantly! Something was definitely amiss. A quick test of whether the problem described below is your issue or not, make sure the black cap and the white housing are solidly attached. Pull apart and push together either side to confirm they are indeed solid.

    Turns out there are two small screws that hold the sleeve in place. The "sleeve" I am referring to is what the heat shield snaps onto. On either side, there is a small flange under the screws that should hold everything solidly attached. Turns out, one of my flanges had cracked and this is what let that side to flop around. Of course, this sent me to a scramble to find a small washer to at least grab the remaining tab I could catch to hold things in place. Luck would have it (I salvage hardware form everything going to trash) I found a perfect large flange screw that was the right thread and pitch. That solved my issue.

    X2.png


    I did a quick test print with the Infinity Rinse and all seemed to hold up well. There is an ever-so-slight difference between the two nozzles. The right side is just a hair, if that much, higher than the left. The print head is now fixed and the heat shield is in place. I am now ready to test out the Infinity Rinse on larger projects. Maybe I'll do some dual color prints first.

    If you were even on the fence about correcting your nozzle level from left to right, I hope this gives you a little more confidence that it can be done.

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  3. #2
    Administrator bolsoncerrado's Avatar
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    Man what a bible are you builing

  4. #3
    3D Printer God(dess)
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    We're going through the test of time ...and thermal stress with these gadgets.

    Okay, maybe a little abuse as well.

    - - - - - - - - - -

    I really need to convince myself that running 2 extruders full time is doable.
    I'm thinking adhesion issues will be more prominent.
    Plate placement may come into play here.

    - - - - - - - - - -

    That wasn't hard to confirm... 2 nozzles present really is another level of failed print potential.

    This print came out "okay" but it had some serious bed shifts.

    x4.PNG

    What you are looking at is a support for my Thingiverse Qubit.

    Although the print itself was going along as perfect as usual, once the support pieces started getting a little wigglier, and the infill has a few "snags" sticking up, the whole plate would be shoved laterally by centimeters only to settle back where is though it wanted to be. When the snag happens, it would catch a support on the second nozzle and lever the support under the print head creating a significant disturbance. This caused a few misalignments in the main print. Not as drastic as shows in the supports, but certainly enough to fail a print to a customer.

    The reason I like the idea of keeping 2 extruders present is that they often get stuck in the print head when cold. Removing the B2B nozzle hot is something I am trying to avoid out of principle (not failed one yet, but I know the potential is there).

    Right now I have the Infinity Rinse in the right bay. I'll keep it this way for a while and see what else fails due to the potential snags.

  5. #4
    Administrator bolsoncerrado's Avatar
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    Yikes! Perhaps with some supports, indeed...

  6. #5
    3D Printer God(dess)
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    I ran a puzzle piece with 2 extruders in place. It never snagged. Came out beautiful.

    I suspect it is something you want to decide on a case by case basis.
    Level of risk and all that.

    - - - - - - - - - -

    Turns out this little support works well for spheres...

    x8.PNG

    - - - - - - - - - -

    Oh, and the adjustments seem to be holding up.

    I need to print something dual color to see if this working as I expect.

    One thing I did finally figure out in all this effort is how this little heater block is made.
    Quite clever if I do say so myself.

    They use simple power resistors for the heaters.
    Wattage should be easy to figure out based on size, which is perfectly visible.
    No one has done a good resistance measurement on it in the OpenBuilds forum.
    So a resistance value would be nice.
    The one part that makes this hole part fragile is the hole in the center.
    Turns out there is a "Hail Mary" thermal switch in the cavity.
    Nice to know that in the case of fire, it will cut off the power to the heaters :| !

    Here is a clean shot of the hot-end that should help understand the components in the circuit...

    x9.PNG

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