Jump to content
Ultimaker Community of 3D Printing Experts

Top Layers not touching - UM2


Nicolinux

Recommended Posts

Posted · Top Layers not touching - UM2

And I remember you used to fail at 4'3'mm/s. 13 is really good and I think you should be glad with those results.

 

I sure am. The underextrusion problems are gone with the new UM2. I just tried to make a connection to the actual strands not touching problem.

 

  • Link to post
    Share on other sites

    • Replies 526
    • Created
    • Last Reply

    Top Posters In This Topic

    Top Posters In This Topic

    Posted Images

    Posted · Top Layers not touching - UM2

    I would suggest printing a larger cube aligned with the bed edges and with the infill at 0 degree.

    The idea is to "separate" X from Y and see where the issue appear, on a wider perspectiive.

     

    I did, here are the results:

    infill angle 0

     

    It looks alright when it is on the bed, but a bit wonky when held like this (I rotated the image to match the printing orientation):

    infill angle 0-2

     

    I then printed another one with the infill at 90 degree (to get the other axis):

    infill angle 90

    The heat distribution is not even (it is worst on the top left corner).

     

    Hi Nico,

    Usually you have to print white at a slightly higher temperature then other colors.

    Have you also tried other colors and with what temperature it disappeared?

    Maybe, because the hot end on the Ultimaker 2 is different, you should not hold on too

    tight to the profiles you used to create for the Original.

    For example, have you tried printing this model and see if you had any stringing?

     

    I have printed with other colors or course and at higher temperatures. The strands not touching problem is never gone, just very much less visible with higher temperatures. And it always is worst on the upper right corner of a print. That's why I think that it is something mechanical.

    I also printed the hollow pyramid but the stringing at 230° was not that pronounced compared to 210°.

    (210 left, 230 right)

    stringing test

     

  • Link to post
    Share on other sites

    Posted · Top Layers not touching - UM2

    Awesome pattern :)

    I don't know if the top-left corner of the print corresponds to the front-right side of the printer where, if I'm not wrong, you found an issue on the mechanism (post #93), but could be related to it.

    The pattern remain the same, no matter the printing direction.

    And repeats regularly, apparently on both X and Y (looking like stationary waves). Given the particularities of UM, using parts of one axis mechanism for the other axis as well, this may imply that an issue on one part, may actually impact on the other axis movement as well.

    By now, I can understand that, if something happens periodically on, let's say X, it will also periodically affect Y and that's how a "square" pattern appears.

    The fact that the impact is more adverse should be related to the faulty corner. Logically should be the same, but I suspect is the opposite, which confuses me a bit).

    The periodicity indicates that the the effect is given by... rotation.

    Now, the frequency of the pattern. Looks like 3-4 cm or so ;) This is pretty close to what I can estimate is the diametral pitch of the pulley.

    Why "under-extrusion"? Since there is no reason to question the extruder feed rate, an alternative would be that the axis is travelling... faster and then is slowing down and repeat. This looks again like a consequence of something similar to the belt "climbing" on the pulley side hence "riding" a larger diameter.

    I think the logic by now works with the given facts. However, why not on the first layer, this is something that does not fit yet my mind :)

     

  • Link to post
    Share on other sites

    Posted · Top Layers not touching - UM2

    Why "under-extrusion"? Since there is no reason to question the extruder feed rate, an alternative would be that the axis is travelling... faster and then is slowing down and repeat. This looks again like a consequence of something similar to the belt "climbing" on the pulley side hence "riding" a larger diameter.

    I think the logic by now works with the given facts. However, why not on the first layer, this is something that does not fit yet my mind :)

     

    The belt climbing issue is resolved - I printed my own spacer and replaced the one that was wrongly used on the bottom right rod. I couldn't find other places where the belt behaves in an unexpected way.

    And regarding the first layer - that's pretty easy to explain. Since the first layer is wider than the rest (0.3mm) it just hides this problem by making the strands overly wide. On the two prints above I changed the first layer height to 0.2mm (still have not got to grips with Simplify3D - this was my first print with it).

    I think I will finally take out the rods today, check them if they are straight. I will also check the pulleys. Not keen to do it, but won't accept status quo either :)

     

  • Link to post
    Share on other sites

    Posted · Top Layers not touching - UM2

    Just another remark. The bright spots (where the light shines through) are the spots where the strands do not touch at all. That's why the square looks so frazzled. So this is not a minor issue for me.

    infill angle 90

     

  • Link to post
    Share on other sites

    Posted · Top Layers not touching - UM2

    Just curious: when you say "layer width", do you mean "layer height"?

     

  • Link to post
    Share on other sites

    Posted · Top Layers not touching - UM2

    Yes you are right - I meant layer height... Updated the post. thx

     

  • Link to post
    Share on other sites

    Posted · Top Layers not touching - UM2

    hi guy's

    i'm intrigued by this discussion and the difference in the layers touching and not touching

    I think i can partially explain why in the cube middle part gives more problems than the sides.

    The difference in temperature has been shown to be very subjective to change by Mnis in his previous post

    Because the head slows down at the corners in the red circles the material has more time to take in heat energy, then when the head speeds up again in the green corners and the material gets pushed through faster it has less time to take in the energy needed to be fluid enough to prevent under extrusion.

    gallery_9987_1180_60119.jpg

    This has been a sensitive spot in the Ultimaker 2 hot-end. Because the area where the material is being heated is fairly small these temperature drops are more likely to occur then in the Ultimaker original where the heating zone is larger. (+/- 1 cm Larger with a lot more mass so it won't fluctuate as much as the original)

    But this also results in the fact that the ultimaker 2 can print more detailed/fine models than the Original where to much material just leaks out and its harder to control the constant flow.

    Another thing that is a result of the different melting chamber height/mass is that the temperature input needed to get the PLA up to an certain temperature is different on both machines, and printing on 210c on an UM2 might result in the same extrusion temp as 190c on an UMO.

    So, printing a little slower might help the material to get up to temp and might fuse the layers together better.

    Making sure the extruder drive is set at the correct tension is always a good place to start with under extrusion. (my personal favorite is placing the indicator around the second notch). as well as checking if the knurled wheel is tightly secured.

    gallery_9987_1180_645535.jpg

    Can you also show me a picture of the pattern embedded in the PLA after it has been through the extruder?

    As for the patterns in the red printed squares, i think 3Dmaker4U gave a very plausible reason for the patterns,

    The layers releasing in the top left corner might be because of the uneven heat distribution, it might be an slightly warped glass plate and small differences can show up only in large prints.

    I'm looking forward to see what people think about my little talk :)

    and i hope it helped a little

     

  • Link to post
    Share on other sites

    Posted · Top Layers not touching - UM2

    Now, seeing the extruder picture above, I'm wondering if a full rotation of the motor, for the given printing speed and the circular pitch of the knurled bolt would be.... synchronous with the red pattern. This might be another possible cause for the under-extrusion (this time really that).

     

  • Link to post
    Share on other sites

    Posted · Top Layers not touching - UM2

    @3Dmaker4U: If that's the case, then my former tests with flow rate up to 150% should have produced different results, but the strands were still not touching. Also looking at the underextrusion test where it fails really late (between 13-14mm^3/s) I'd say this printer doesn't have problems with it.

    @MartijnvG: Thanks for the detailed response. Yet I still think this issue is unique to my printer (or others as well who don't care much about surface quality).

    I did some more tests:

    Printed the standard 20mm cube at different speeds and feeder settings. Default print settings for all cubes:

    • layer height: 0.2
    • shell: 0.4
    • bottom/top thickness: 0.6
    • infill: 0
    • travel speed: 150
    • combing: disabled
    • location: center of heated bed

    230 40

    230 20

    230 40 tight

    230 40 tight new extruder case

    There is no real difference between 40mm/s and 20mm/s. Also the temperature (230°) is pretty high for these low speeds. I've also changed the feeder in between (Bas sent me a new case with the metal grommet). For the "tight" tests, I've set the tension at the second notch.

    Here are two closeups of the filament that has been through the feeder:

    This one is with retraction involved (during a print).

    filament retraction

    And this one is just through the feeder once during a print (I undid the bowden at the feeder and just let it move through). The filament didn't reach the hotend, so I guess here, less back-pressure is involved.

    filament normal

     

  • Link to post
    Share on other sites

    Posted · Top Layers not touching - UM2

    Nico,

    Did you manage to fix this problem?

     

  • Link to post
    Share on other sites

    Posted · Top Layers not touching - UM2

    No sadly not. I didn't have the time to take out the rods and the pulleys and I had hoped someone had a better idea in the mean time.

     

  • Link to post
    Share on other sites

    Posted · Top Layers not touching - UM2

    No sadly not. I didn't have the time to take out the rods and the pulleys and I had hoped someone had a better idea in the mean time.

     

    I wish I could help you must be very annoying! if I see anything else about it online I will let you know!

     

  • Link to post
    Share on other sites

    Posted · Top Layers not touching - UM2

    No sadly not. I didn't have the time to take out the rods and the pulleys and I had hoped someone had a better idea in the mean time.

     

    Also what do you do your 3D work in?

     

  • Link to post
    Share on other sites

    Posted · Top Layers not touching - UM2

    Hey thanks Matt.

    What do you mean with 3D work? Do you think the software might be related to this problem? I have printed all sorts of objects - mine and from other people and the problem persists.

    Other than that, I am not doing much 3D work right now. But when I do it it is either OpenSCAD or Moment of Inspiration.

     

  • Link to post
    Share on other sites

    Posted · Top Layers not touching - UM2

    Hey thanks Matt.

    What do you mean with 3D work? Do you think the software might be related to this problem? I have printed all sorts of objects - mine and from other people and the problem persists.

    Other than that, I am not doing much 3D work right now. But when I do it it is either OpenSCAD or Moment of Inspiration.

     

    I am not sure, I am quite new to 3D printing etc... but quite experienced with electronics and technically minded, do you want to send me the cube stl, i'll print it on mine and see what happens, also tell me the full settings you use?

     

  • Link to post
    Share on other sites

    Posted · Top Layers not touching - UM2

    Thanks for the offer. I am printing the 20mm-box from this set (it is just a simple box):

    http://www.thingiverse.com/thing:5573

    Print settings:

     

    • speed: 40
    • temperature: 230
    • shells: 0.4
    • top/bottom: 1.2
    • fill: 0

    I have attached the gcode file here:

     

     

    I am also printing other objects (this is a bigger part from the 3DR delta printer). Here you can see that strands not only tend to not touch but some strands are a bit raised.

    Oh strands why no thouching thou

     

  • Link to post
    Share on other sites

    Posted · Top Layers not touching - UM2

    A few thoughts...

    1) Have you tried simply increasing the flow rate to make up for whatever under-extrusion you're having. There's going to be some back-pressure related under-extrusion at pretty much any speed; so trying to compensate for that might help.

    2) You picture in post 106 - the single layer red square? It looks like the spacing of the darker patches is very regular in both x and y. What is the distance between the centers of the patches? If we can figure out what that corresponds to, then we should be able to figure out how to fix it.

    3) Unplug the bowden tube from your extruder, and then use pronterface to run some filament quickly through the extruder, while videoing the motor shaft and tension bearing. Look to see if there's any visible oscillation due to the motor shaft not being straight. That might cause periodic variations in extrusion amount.

     

  • Link to post
    Share on other sites

    Posted · Top Layers not touching - UM2

    Thanks for the offer. I am printing the 20mm-box from this set (it is just a simple box):

    http://www.thingiverse.com/thing:5573

    Print settings:

     

    • speed: 40

    • temperature: 230

    • shells: 0.4

    • top/bottom: 1.2

    • fill: 0

    I have attached the gcode file here:

     

     

    I am also printing other objects (this is a bigger part from the 3DR delta printer). Here you can see that strands not only tend to not touch but some strands are a bit raised.

     

    Printed with your gcode and 230c, blue ultimaker PLA, this is what I got

    IMG_2803_zps22cae8c5.jpg

     

  • Link to post
    Share on other sites

    Posted · Top Layers not touching - UM2

    Hi,

    Just a short note. I haven't had time to work on this issue but will attend to it asap.

    @illuminarti: Awesome ideas. Regarding the flow - I tried printing with up to 150% flow and it was only very slightly better. As for the other two suggestions, I will have to re-print the flat object to measure the distance between the spots. Also the idea of watching the extruder motor shaft is great. Will do it.

    @electronic_matt: Thanks for the print and welcome to the club. You seem to have a simmilar issue :/

    Except if my Cura is wonky and slices things like that - while not totally impossible, would be otherwise a huge coincidence - but who knows.

    Maybe one of the other fine lads could give the cube a spin (beware - UltiGCode):

     

     

  • Link to post
    Share on other sites

    Posted · Top Layers not touching - UM2

    Hi,

    Just a short note. I haven't had time to work on this issue but will attend to it asap.

    @illuminarti: Awesome ideas. Regarding the flow - I tried printing with up to 150% flow and it was only very slightly better. As for the other two suggestions, I will have to re-print the flat object to measure the distance between the spots. Also the idea of watching the extruder motor shaft is great. Will do it.

    @electronic_matt: Thanks for the print and welcome to the club. You seem to have a simmilar issue :/

    Except if my Cura is wonky and slices things like that - while not totally impossible, would be otherwise a huge coincidence - but who knows.

    Maybe one of the other fine lads could give the cube a spin (beware - UltiGCode):

     

     

     

    I will try printing your gcode file tonight after work and see how it goes.

    I don't know if it will help but have you tried a complete uninstall of cura then download and reinstalled the current version from the website? I saw you reverted back to 14.1 at one point but try a full clear n reinstall with new files. I figure it is worth a try as it only takes a few minutes.

    If you do Ebay that printer please give the bidders a heads up about the issues it has.

     

  • Link to post
    Share on other sites

    Posted · Top Layers not touching - UM2

    ok i printed your gcode and got the same results as you with gaps between infill on the top. So I made a 20x20x6mm cube in sketchup and ran it through cura 14.7. printed at .8 walls, .15mm ,230c, 45mms, 20% infill , silver protoparadigm PLA. and it came out perfect. UM2

     

  • Link to post
    Share on other sites

    Posted · Top Layers not touching - UM2

    OMG!

    Don't tell me this is a sofware fail. Renthal, could you please share the .gcode file? I'd like to print it NOW :)

     

  • Link to post
    Share on other sites

    Posted · Top Layers not touching - UM2

    @Nicolinux: I just checked your gcode file. Did you intentionally use zero infill? That's the main difference to Renthal's file I guess... with zero infill you certainly cannot expect top layers to be closed after less than - uhmmm - maybe ten layers or more... :?: Please just ignore me if I mixed something up...

     

  • Link to post
    Share on other sites

    Posted · Top Layers not touching - UM2

    Yes I did choose zero infill because I wanted it to print fast and only did care about top and bottom layers. But since I spot the "strands not touching" problem even after the second layer, then I guess this does have anything to do with infill.

    Ideally, without this problem, every layer should be water tight - completely closed with no spaces between strands.

    Here is a little explanation. Top view of a partially filled cube:

     

     

  • Link to post
    Share on other sites

    Create an account or sign in to comment

    You need to be a member in order to leave a comment

    Create an account

    Sign up for a new account in our community. It's easy!

    Register a new account

    Sign in

    Already have an account? Sign in here.

    Sign In Now
     Share


    • Our picks

      • New here? Get ahead with a free onboarding course
        Hi,
         
        Often getting started is the most difficult part of any process. A good start sets you up for success and saves you time and energy that could be spent elsewhere. That is why we have a onboarding course ready for
        Ultimaker S5 Pro Bundle, Ultimaker S5, Ultimaker S3 Ultimaker 2+ Connect.   
        They're ready for you on the Ultimaker Academy platform. All you need to do to gain access is to register your product to gain free access. 
        Ready? Register your product here in just 60 seconds.
          • Like
        • 8 replies
    ×
    ×
    • Create New...