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Almost always missing layers / underextruding


Nicolinux

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Posted · Almost always missing layers / underextruding

I was curious about this problem and like a kid I took my extruder housing apart and saw a big reason for under extrusion looking back at me.

I documented what I spotted and reported it to ultimaker. Seems like ultimaker was already on the case and working away like little possesed demons getting the job done and fixed.

So I wont be surprised if we see an official solution to this design weakness very soon.

It seems like this problem is not effecting all users but when this design is changed and released to users, the chance of under extrusion problems will be ... reduced !!

Ian :smile:

 

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    Posted · Almost always missing layers / underextruding

    one of the main problems is... easy... under the massive pressure on the spring. the white turning handle is pushed right down... pushing the rotating wheel in.

    The internal structure and design of the housing was incorrectly designed...

    so the wheel crushed aginst the two walls marked above.

    this stops the movement of the wheel.

    so filament gets dragged along the wheel and the extruder gear tries its best to do all the work....

     

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    Posted · Almost always missing layers / underextruding

    ....... under extrusion !!

     

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    Posted · Almost always missing layers / underextruding

    Ok, many thanks.

    I think I had the issue with the screw (top left) crashing down and thus pushing the spring down. But all in all, doesn't this only affect the enclosure when there is no filament inserted? Because, with filament, the ball bearing would push against it, and not the case.

     

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    Posted · Almost always missing layers / underextruding

    the spring is very strong.. technically too strong. when the filament goes in, the wheel is still pushing to the left, making the filament flow up straight, then to the left,, between the extrider and the wheel, then a little back right and out...

     

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    Posted · Almost always missing layers / underextruding

    I know ultimaker are finding solutions to this problem now.. but I cant resist and am putting together my own solution model in solidworks at the moment :-)

    Untitlghhed-1.jpg

     

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    Posted · Almost always missing layers / underextruding

    I probably will just drop all my work and research onto youmagine tomorrow and let every one pool their resources together and crack this little cookie now...

    Ian :-)

     

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    Posted · Almost always missing layers / underextruding

    Is this possible on YM right now? Last time I checked there were no collaboration features.

     

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    Posted · Almost always missing layers / underextruding

    havent tried yet... but i can put all the files up... photos... model stuff and save people some time and stress.

    remove these problems and printing reliability on the ultimaker 2 will... for some dramatically increase.

    I think the idea that the hotend is causing these under extrusion problems is not correct... I think a lot of the under extrusion comes out of the layout of the extruder housing.

    Ian

     

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    Posted · Almost always missing layers / underextruding

    But how could some of this issues be relevant only for some users? Are not all UM2 extruders alike?

     

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    Posted · Almost always missing layers / underextruding

    users that heavily use their ultimaker put more wear quicker on the extruder housing and well.. it starts to fall apart a little inside... so heavy users.. problem... people that like to print a toy for their kid once a month... no problem.. well for now...

     

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    Posted · Almost always missing layers / underextruding

    but look im like you...im zero expert and dont work for ultimaker... im just an Industrial designer that spotted some off things in the extruder design..... ultimaker are on the case I know that.....

     

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    Posted · Almost always missing layers / underextruding

    Well then count me in to the second group. My longest print didn't even surpass 5 hours. And when I think at illuminarti's monster prints - his extruder must fall appart already :)

     

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    Posted · Almost always missing layers / underextruding

    atleast people will start to realise better why under extusion is happening...

    thats better than all of us smashing out working hotends into a million pieces every day looking for a mystery clog that doesnt exist...

     

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    Posted · Almost always missing layers / underextruding

    think of it this way... flow problem.... there are only 3 parts to this process... extruder... bowden tube... hotend.

    to be honest the hotend is pritty good and I havent really seen any signs of big problems there.. the bowden tube is a no brainer... then you start looking closer at the extruder.

    I actually think myself the power of the extuder included in the ultimaker2 is strong enough.. I just think the filament is being badly handled within the extruder housing.. the whole design is a little wrong..

     

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    Posted · Almost always missing layers / underextruding

    It seems like the problem is fairly marginal thing, and it's only with the right combination of circumstances that it becomes any sort of problem - variations in manufacturing and assembly tolerances, spring tension etc, can add up to the point where it becomes a problem.

    I can't speak for UM, but I'm pretty sure that once they figure out the issue and fix it, they'll make sure that everyone with issues gets taken care of.

     

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    Posted · Almost always missing layers / underextruding

    After reading ian's post and thinking about it quite a bit I disagree with most of what he says except a few things - I see *several* possible ways that the extruder can degrade and chew up and cause pieces of ABS to get into the nozzle causing underextrusion. Ian highlighted those. I do *not* see any problems (that he pointed out) that would result in under powered extruder. And the bottom left comment - I think that's a feature - not a problem. Or maybe I don't understand. There's plenty of room for movement on my UM2. When I feed the filament in I see the idler move over just like it should. No problems there for me.

    I know the black piece is ABS because that's one of those secret things that the moderators were told (by Harma) in a private conversation. It's not a secret that the black piece was ABS. She may not have even leaked any secrets. But it was a private conversation.

    It may seem like I have special knowledge but it's barely more than anyone else knows and I get it probably long after everyone else at UM knows and probably not long before it's posted publicly.

    I don't know what the white piece is made of.

     

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    Posted · Almost always missing layers / underextruding

    Ok, guys, what do you think of the teflon coupler issue? Is it really a good idea to file away the lip?

    Chrisp, braddock - did you see any improvements after you did it?

     

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    Posted · Almost always missing layers / underextruding

    Nicolinux,

    My answer would be yes, only because mine was 2.5mm I.D. when it is supposed to be 3mm. My filament didn't pass through.

     

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    Posted · Almost always missing layers / underextruding

    I used a 3mm drill bit and spun it by hand.

     

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    Posted · Almost always missing layers / underextruding

    You should push some filament through and if it takes a significant amount of force then drill it. Otherwise I'd be afraid to mess with it.

     

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