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  1. #1
    3D Printer Noob
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    Finally Getting Around to Trying to Get My Cube3 Working

    After almost immediately having filament snap and break through the guide tubes when I first got it, I've been putting off dealing with my Cube3. Now that I found this forum, though, it looks like there are some good solutions to make it actually print.

    At first I started printing up the Extruder Hub, but after a couple failed prints it became clear I need to do something about the bend radius in the line between the cartridge and nozzle. I've read through a bunch of threads and I think I know what I need to do. I have some 3/2 PTFE tubing and 4/M5 quick-connect fittings; now to figure out how to go about drilling the head with my limited tool set (living in an apartment will do that).

    Also, I realized the fact the cartridges have been sitting around for a couple years at this point isn't helping the issue with filament breaking. I'm in sort of a catch-22 where I can't print modifications because I need the modifications to print.

    Maybe what I should be asking before I start getting in too deep is: is it even worth it or should I just get a printer that doesn't rely on discontinued proprietary filament cartridges?

  2. #2
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    It is indeed worth it! Okay, for us die-hards, definitely. Then again, I will say that the production of ReCube cartridge fill wands depends on Cube3 working since it is a Cube3 that prints all the cases. So reliability and consistency is a must and I personally feel we've hit that stage with the mods discovered through the help of many great people on this forum.

    I replied to your PM before reading this so I now have a little more information. Let's solve your breaking filament first.
    Let it be known that some of the crappiest 3D Systems PLA filament I've owned still went through the printer perfectly and made some very fine parts.
    Secret; don't leave old PLA filament in the bowden tube overnight. We go to "Brittle Spool Protocol" where the filament is fed into the cart from the outside and removed when the print is done.
    Why you may ask? Brittle filament is prone to micro-cracking. It is just happy as a clam being wound on the spool. But that 'straightening' as it goes into the bowden tube causes tiny cracks in the filament on the inside of the bend. During normal printing, this crack cannot propagate into a complete break in the time that the filament takes from being unwound to the time it is melted. Problem avoided! But leave that in the bowden tube overnight and those little micro-cracks become full blown cracks that eventually snap the filament.
    As to full disclosure - peeps claim to have 'rejuvinated' the filament in an oven at a low temp. I'll stick with BSP personally

    P.S. 2mm ID x 3mm OD tube is too big to fit properly in the nozzle. Stock is ~2.8-2.9mm. If the tube you have fits the nozzle tube, which is 3mm exactly, means that your tubing is dead on size or slightly undersized, which is a great thing. But do test it to make sure it is no bigger than 3mm. By the same token, I will warn about 3mm OD tubing in quick connect fittings. Although it has been reported to work, my experiment with 3mm tubing is that the tube just peeled out of the 3mm fitting. My experience, but I thought I'd better share that in case you experience the same.

  3. #3
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    Ah that makes a lot of sense about the microcracks. The one successful print I had was started immediately after I cleared out old filament. The one I tried the next day failed twice almost immediately.

    You're right about the 3 mm tubing being too big. I hadn't even thought about how that was supposed to work. So the trick then is how to transition from the new tubing to the slightly smaller stock tubing in the extruder head? Hence the quick-connect fittings? I probably shouldn't have been quite so rough getting the barrel nut off then... I can see about trying to get a hole tapped and see what happens though.

  4. #4
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    No worries. Yes, you can tap your PC3-M5 fitting into the plastic housing. You don't need the barrel nut. A length of stock tubing will be trapped inside the housing between the end of the stainless tube [20mm deep] to the 'flush face' of your fitting with a 2mm hole. No chamfer! Dead stop for the tubing.

    I've done fittings at 15 degrees from center. Straight works too. You have to clear away material for the body of the fitting. Not to worry, you can print one as soon as you get hobbling along. Thingiverse...here

  5. #5
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    Alright I have a tapped hole and a PC4-M5 fitting in.
    modified_housing.png

    The tube inside doesn't quiiiite line up though.
    tube_misalignment.png

    Maybe I can try shimming it to get it to line up. Also the filament doesn't seem to move very smoothly through the fittings anyway. I'm not sure whether they're too small or I just need to hit it with a rasp or something. Or maybe the tubing I have just isn't a good fit so it's not controlling the exit point well enough.

  6. #6
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    ...or the filament will make sure it stays in place Not sure why you'rs is different. Mine had a nice defined path to that location inside. But it will do.

    Did you say PC4-M5? Weren't we working with 3mm tubing? :?

    Anyway, it will run for a while. Be sure the filament has sufficient clearance coming out of the fitting. Filament is part of the guide string although true, you're not suppose to depend on that

  7. #7
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    If the filament ever breaks though it seems like an immediate failure once it reaches the transition. Maybe I'll give it a go anyway and see what happens. And yeah I have PC4 fittings, which would definitely not have worked. I just got some 4 mm tubing though so hopefully that'll do it.

  8. #8
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    I have printed up some very old grungy filament before. As long as it feeds well and is coming off the spool directly, it should make it to the nozzle before snapping. If not, try one of your other filament. I just know that overnight is more than enough to cause the break to propagate. And I would print that nozzle on Thingiverse first You may have to clean out the bore of the 'core' for the 42mm tube segment, and you may have to clean the inside of the nozzle housing bore with a piece of sandpaper, but once you have the printed nozzle, even printed in PLA, you are well underway to getting things fixed.
    Last edited by TommyDee; 10-07-2019 at 11:56 PM.

  9. #9
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    20191007_203036.jpg
    20191007_203053.jpg

    Well it kept extruding the whole time, so that's something! I assume this is supposed to be a smooth hole though?

  10. #10
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    Um... yea... no! That ain't right!

    You hit a slicer mode where there is a minimum layer time required. This usually makes only globs.

    I print the nozzle 2 up with core, housing, and several keepers. Otherwise consider a priming tower to avoid the minimum layer time limitation.

    Didn't I upload this .cube3 file to thingiverse? Oops... ABS.

    20190414_131630.jpg

    Keep an eye on the rotation of the parts. There is a teardrop relief for the blobs at the seam in the 2 bores.
    Last edited by TommyDee; 10-08-2019 at 03:10 AM.

 

 

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