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BiaC

problem with nozzle?

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Hi. I'm getting like the printer (i3 mk8, 0,4 nozzle) doesn't raise goodly the printhead, and the nozzle acts such as engraving upon the previous trail. Some details are also missed. Googling I've stumbled upon a similar problem herein, but not identical: someone suggested that it might be a software prob.

I'm with Cura 3.4.1 printing with default 0.4 values (plus retraction) (curiosly, the 0.4 layer height box appears orange). I changed the old threaded shafts (standard 8mm) and put a new stepper on the right column (the one looking to the machine).

 

vf.jpg

Edited by BiaC

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This problem is called "overextrusion".  By the way, don't say "goodly", say "well".

 

One common cause is if you Z axis is moving the wrong amount.  It may be moving half as far as it is supposed to.  Try moving the Z axis 30mm and measure how far it moved.  If it only moved 15mm then you have narrowed down your problem nicely (to the printer, not cura).  (steps/mm is wrong for Z axis).

 

Another common problem is filament diameter - saying you have 1.75mm when you are actually using 3mm filament.  This also causes overextrusion.

 

Another common problem is that the extruder is moving the wrong amount.  With the nozzle removed and the head cool try moving the filament 100mm and measure how far it moves.  If it actually moves 200mm then this is the problem (steps/mm setting is wrong for extruder axis).

 

Make sure flow is set to 100% (not 200%).  I see in your picture this is fine.

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Hi. As you see, the filament is 1,75, the flow is 100%, the temp is 180, and the nozzle in the setting is 0,4mm, for an i3 profile. This problem has surfaced after I installed the latest 3.4.1: previously so far Cura worked well. The threaded shafts looks like they don't receive the instruction to twist up and raise of 0,4mm for every each new layer, so the nozzle furrows upon the previously printed trails: so for example I get a 1cm high object printed as it were just 0,5cm. And, I do not see any evident raising of the threaded rods, throughout the whole printing process (although I guess that somewhat it must happen, probably imperceptibly, if being just a half of what expected). Perhaps that reddened 0.4mm layer height box is highlighting some problems with that, but I cannot figure it out what. And I didn't modified nothing on that sequence (except from the wall thickness, just for a test: but the reddened thing was already there before): that reddened thing appears by default that way when I select the coarse quality 0.4mm setting from the dropdown.

Edited by BiaC

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It is reddened because cura is warning you that a 0.4 layer height is too high for a 0.4 nozzle.

Ideally you should set layer height to about max 90% of nozzle diameter, so try 0.35 layer height.

 

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Well, but if it were too high, it should be anyway good and better that a lower value. Otherwise, what would be the sense to allow a 0.4 preset for a 0,4 nozzle, if it shouldn't match its very own height? Btw, previously the machine worked well with that setting, which didn't sported any reddening. Besides, if I use a 0.2 preset, the reddening it is not present in the 0,2 box, but each subsequent layer will furrow upon the previous one anyway, cutting it in half as the 0.4 one. I confirm that somewhat would be investigated with some specifics of the software, 'cause I'm tring a test to print the same model with another slicer (I'm sad to use competitor's stuff, but it's for the sake of the investigation: I was and I would still like to remain faithful to Cura, 'cause I deem it more precise specially with the cleanness of the trail, besides many other advantages which it haves) and it is coming out decently with a 0.4 setting.

Edited by BiaC

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14 hours ago, BiaC said:

previously so far Cura worked well. 

 

So why not just go back to the version of Cura that worked well for you? What functionality does this newer one have that made you ditch the older one?

 

Like i say to many people here, if it ain't broke don't fix it!

 

Because you will be running into these problems a lot. Escpecially using software thats not designed specifically for your machine....a not Ultimaker.

 

...but also dont get angry. Some people tend to get angry when you advise them in good spirit not to upgrade, thinking they are somehow missing out using software that doesn't work for them anyway.....

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Well, but I hope anyway that the coders would aknowledge that sometimes newer versions may have issues, such as the one I'm on. The fact is also that it is very uneasy for somebody to downgrade whilst the most of people upgrades without any problems.

Edited by BiaC

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well if it looks better quality overall then i guess its worth pursuing a fix...

 

...or go back a version and wait for an even newer one to come out and just skip one out. don't worry about following the crowd.

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Ok I reverted back until the 2.5: nothing changes. The printer prints just until a half or so. I even tried to use a 0,3 value instead of 0.4 and selected the "z-hop when retracted".

Edited by BiaC

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Not sure mate. Im more of a creator than mechanic. Luckily i have only ultimakers.

 

All i cam say is try and remeber the last fully working scenario. And go from there, crossing off one variable at a time. 

 

Did you update any firmware? That might change stuff? 

 

If everything was working at one point, just try to get back to that point and then try new things out.

 

Lots of knowledgable people here but i can vouch Gr5 knows his stuff!

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Okay BiaC - you need to learn how to do some debugging.

 

Why didn't you try moving the Z axis exactly 50mm (or some other value) and see if it really moved 50mm?

 

Many controller boards (don't know about prusa) have jumpers that can halve or double how much the Z axis moves.  Maybe you removed a jumper or plugged a fan into a jumper spot instead of the correct spot.

 

If the prusa front panel can't move the Z axis manually - for example 10mm exactly, then get pronterface (windows only) and move the Z axis using pronterface.  It's free and easy to use and can be found here:

http://koti.kapsi.fi/~kliment/printrun/
 

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Oh - and I really really really doubt it's cura.  But you could just look at the code and search for "Z" in the gcode file.  There are very few Z's in the file - it's quite self explanatory - just do it.  But don't do it - because this has nothing to do with cura.

 

And if the Z axis checks out okay then check the E axis (extruder).

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Hi gr5: infacts, I'm not sure either that it would be caused by Cura, having specified that the problem is replicated also with another slicer. The only motivation for I alleged something about Cura, is that reddened box, that's all. I trust Cura and I want to use only it, and I'm never sure that upgrading may come to a malfunction of the machine: infacts, time ago I posted a post about another kind of problem alleging that the problem would be given by some issues of the machine and in only last instance given by a newer Cura version (which btw worked anyway after I adjusted the printer...).

Could some sudden shutting of the printer have messed with the machine firmware, causing some axes' malfunction?

Ok: I've not the printer dongled to a pc: I use just the card, to print. I didn't tried to move the axis 'cause simply I dunno how to do it. The plugs wasn't either moved/removed. I've seen in the lcd menu that there's something about axes, lemme see and I'll report. TY.

@cloak nope, no firmware upgraded. Still the same as from outbox.

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I'd already done it, but I cannot afford it right now. And I don't know how and when I'll be able to do it. Anyway it's an option. though, now I'm involved with solving this: I've used this machine since 3 ys and it didn't gave any probs so far. Neither gave Cura.

Edited by BiaC

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As a sidenote, Cura shows your layerheight with an orange background to tell you this is probably not going to get you great results with a 0.4 mm nozzle. You want the extruded material to be squished a little into the previous layer. 

 

You generally need a layerheight that is at most about half of the nozzle diameter.

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@gr5 sorry I didn't understood. Thanks. I have to install it in a notebook, but I doubt that I can manage the printer, 'cause time ago I had it dongled to a pc but it wasn't recognized. Though, I remember that in the pdf which came in the cd of the machine there was pronterface mentioned. I never understood why the machine wasn't recognized: but I had the card, so I moved ahead.

@ahoeben tried both 0,2 and 03, same. Due the culprit cannot be Cura, I begin to suspect that the problem is given by the steppers, which cannot get along with the correct height of the model, and raise the height of the extruder at a half or so of the correct height of the model.

Edited by BiaC
mistypos

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