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Retraction or something else?


pim-stolk
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Posted · Retraction or something else?

I am experiencing some problems while printing on my Ulitmaker 1

Printing on with PLA.

I was trying different speeds 50% till 150% and played a bit with the temperature fairing between 200c and 220c but the result is not so good.

Does someone know what the problem might be?

2ducbr7.jpg

 

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    Posted · Retraction or something else?

    Is retraction happening during the print? If it's happening, you'll hear and see the big gear wheel spinning quickly back and forth as it moves between the 'islands' of filament on each layer.

    You need to make sure retraction is enabled on the basic tab of Cura, and then in the expert settings, set the minimum travel to a smallish amount, maybe 1 or 2 mm, and set the minimal extrusion to zero. Also, turn off 'enable combing'.

    Also, you might want to try the most recent test version of Cura, as there have been some recent changes to how retraction works:

    http://software.ultimaker.com/Cura_closed_beta/

     

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    Posted · Retraction or something else?

    I see the problem - your printer is upside down. (just kidding). The slower you print, the less pressure build up you get in the nozzle, and the less stringing issues you have. Also colder temps help because the filament flows like toothpaste instead of honey but this also requires slower printing. For something like this print consider 20mm/sec, .1mm layers, and 195C or even 190C (it's hard to say as every different color and manufacturer has different viscosity at 190C).

    And like Illuminarti said - do the settings he recommends or you might not be getting retraction where you need it.

    Also consider printing this:

    http://www.thingiverse.com/thing:46157

     

     

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    Posted · Retraction or something else?

    I do see retraction happening during a print

    Slow speed and temperature are not helping at this moment.

    I did noticed that my "nozzle" keeps leaking filament when i set the temperature doesnt matter if its 200c or 220c it keeps leaking.

    I think that this might be the problem? but i have no idea what is causing this "leaking".

    23igke0.jpg

     

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    Posted · Retraction or something else?

    The oozing from the head is pretty normal. That is ultimately what causes the stringing that you are seeing, but the solution in practice is not to stop all oozing (no one has managed that yet), but rather to ensure that the filament gets sucked back far enough to prevent the oozing from affecting the print when moving around between parts.

    Looking at you photo, I do see one problem. The fan duct isn't assembled correctly. You have the last flap bent up so that it's blowing air directly onto the heater block and nozzle. That's going to cool the nozzle tip, and cause print quality problems. Most likely under-extrusion, due to the nozzle opening being much colder than it should be, making the plastic more viscous. But it could possibly contribute to stringing problems some if this filament becomes stringier at cooler temps (the behavior varies between different filaments).

    So start by bending that last piece down, so that you aren't blowing air on the nozzle.

    Secondly, what retraction settings are you using? You said that you hear it retracting. Is it doing it on every move between the parts of the print, or just some of them?

    Could you post the gcode for that test print somewhere so that we could take a look at it?

    Finally, it looks like the bed spring in the picture is totally compressed. Not related to you current problem at all, but that is going to make it harder to level the bed and get a good first layer, if there's no play in the springs at all. I suggest loosening all of the screws by a couple of rotations, and then moving the z-limit switch up a corresponding amount as well, so that when the bed is in it's z=0 position, all of the 4 springs in the corners of the bed can still be compressed a little more if needed.

     

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    Posted · Retraction or something else?

    The oozing from the head is pretty normal. That is ultimately what causes the stringing that you are seeing, but the solution in practice is not to stop all oozing (no one has managed that yet), but rather to ensure that the filament gets sucked back far enough to prevent the oozing from affecting the print when moving around between parts.

    Looking at you photo, I do see one problem. The fan duct isn't assembled correctly. You have the last flap bent up so that it's blowing air directly onto the heater block and nozzle. That's going to cool the nozzle tip, and cause print quality problems. Most likely under-extrusion, due to the nozzle opening being much colder than it should be, making the plastic more viscous. But it could possibly contribute to stringing problems some if this filament becomes stringier at cooler temps (the behavior varies between different filaments).

    So start by bending that last piece down, so that you aren't blowing air on the nozzle.

    Secondly, what retraction settings are you using? You said that you hear it retracting. Is it doing it on every move between the parts of the print, or just some of them?

    Could you post the gcode for that test print somewhere so that we could take a look at it?

    Finally, it looks like the bed spring in the picture is totally compressed. Not related to you current problem at all, but that is going to make it harder to level the bed and get a good first layer, if there's no play in the springs at all. I suggest loosening all of the screws by a couple of rotations, and then moving the z-limit switch up a corresponding amount as well, so that when the bed is in it's z=0 position, all of the 4 springs in the corners of the bed can still be compressed a little more if needed.

    Thanks for the detailed feedback and spotting two defects.

    I fixed the duct, it doesn't blow at the nozzle anymore.

    Also i tried fixing the springs and run the leveling wizard again.

    I see it retract when i look at the big wheel on the back, but i have the feeling it isn't always retracting when skipping small gaps.

    Retraction settings Cura:

    347tht0.png

    34yyblu.png

    GCODE


    ;Generated with Cura_SteamEngine 13.11.2
    M109 T0 S205.000000
    T0
    ;Sliced ?filename? at: Sun 15-12-2013 18:53:07
    ;Basic settings: Layer height: 0.2 Walls: 0.8 Fill: 20
    ;Print time: #P_TIME#
    ;Filament used: #F_AMNT#m #F_WGHT#g
    ;Filament cost: #F_COST#
    G21 ;metric values
    G90 ;absolute positioning
    M107 ;start with the fan off
    G28 X0 Y0 ;move X/Y to min endstops
    G28 Z0 ;move Z to min endstops
    G1 Z15.0 F?max_z_speed? ;move the platform down 15mm
    G92 E0 ;zero the extruded length
    G1 F200 E3 ;extrude 3mm of feed stock
    G92 E0 ;zero the extruded length again
    G1 F9000
    M117 Printing...
    66848;End GCode
    M104 S0 ;extruder heater off
    M140 S0 ;heated bed heater off (if you have it)
    G91 ;relative positioning
    G1 E-1 F300 ;retract the filament a bit before lifting the nozzle, to release some of the pressure
    G1 Z+0.5 E-5 X-20 Y-20 F9000 ;move Z up a bit and retract filament even more
    G28 X0 Y0 ;move X/Y to min endstops, so the head is out of the way
    M84 ;steppers off
    G90 ;absolute positioning
    ;
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    Posted · Retraction or something else?

    You need to also look at the expert settings in the Expert menu. There are more retraction settings there.

     

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    Posted · Retraction or something else?

    In expert settings set both retraction distances to 0mm.

     

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    Posted · Retraction or something else?

    Oh - and oozing with warm nozzle when not printing is normal. It's one of the key problems with FDM printing.

     

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    Posted · Retraction or something else?

    I damaged my fan shroud in the same spot for the same reason. I fixed it with kapton tape which can withstand something like 600C. Works great.

     

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    Posted · Retraction or something else?

    You need to also look at the expert settings in the Expert menu. There are more retraction settings there.

    Tried that this is the result.

    It looks a bit better, this is printed 210c with the retraction settings in the expert mode set to 0

    v406lv.jpg

     

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    Posted · Retraction or something else?

    Much better. Now go down to 190C and 20mm/sec and it will likely be *perfect*. But take twice as long to print of course.

     

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    Posted · Retraction or something else?

    Did you also turn OFF 'Enable Combing'?

     

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    Posted · Retraction or something else?

    Yes i did, hope i solved the problem a different way.

    I bought an ultimaker 2, lets hope it does not have the "retraction" problem like my ulimaker 1

     

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    Posted · Retraction or something else?

    Hah, well, that's one way to solve the problem. In my tests, retraction is working pretty sweetly on the UM2....

    http://www.extrudable.me/2013/12/17/highqualityultimaker2/

     

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