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Warping Problems

ProkktorProkktor Posts: 146🌟 Super Member 🌟
Hello,
now that I corrected mit Z Axis height problems, the next step ist warping:
This is the USB Stick Holder I printed yesterday.
My Settings are as following:
215 C initial layer to get it to stick, 195 C all other layers
65 C Bed (it has really strong adhesion, so there must be considerable force at play to warp it and pull the brim of the bed)
100% Fan after the first layer
95% Flow (100% first layer) Because the all in one printer test fails at tolerance tests with 100% flow
all layers 0.2mm
10% infill
Speeds 10/12/30/60  (brim, i layer, walls, infill)

What I already tried:
Tuning the fan down gets me other problems.
Increasing Flow gets me problems with small gaps.
5 C more or less bed temp does not change much.
Dialing down initial layer temp makes the brim less sticky
A thinner first layer is weaker and therefore the warping increases

I clean the bed with alcohol before every print, I do not want to use any additional glue on the bed, its only pla and i am sure it has to work without pva sticks or something.

Any help is apreciated...

kind regards

Martin


Thanked by 1Samuel Pinches
Β«1

Comments

  • Samuel PinchesSamuel Pinches Posts: 2,840Administrator
    edited November 2018
    Hi Martin ( @Prokktor )
    That's odd - very severe warping for PLA!

    I would try a few things:

    Bed Temp: 67C
    Initial layer temp: 212C
    First layer height: 0.12mm
    Infill: 14%
    Wall thickness: 2mm
    Regular Fan Speed at Height: 1.2mm
    Bottom Layers: 8

    See how that goes...
    Cheers,
    Sam
    Post edited by Samuel Pinches on
  • ProkktorProkktor Posts: 146🌟 Super Member 🌟
    Ah yes I simply set the fan to 0 and use a ChaneAtZ Script turn it up in layer 7 :-)
    I will definitely try that!
  • ProkktorProkktor Posts: 146🌟 Super Member 🌟
    Great I simply set the Fan to max at 5mm (3 was not enough) and all warping problems are a thing of the past.
    The squishing the first layer technique also allowed me to insert a ChangeAtZ Script that turns the heated bed down to 30 Degrees at 3mm. This saves lots of power and I have no chances of removing the print while the bed is at more than 25 C anyways^^

     Then I used the information in this Video:

    to print a 28 mm miniature, my very first try is already all the print quality I am ever going to need^^
    The black splodges are a completely new problem... opening thread now...


  • Samuel PinchesSamuel Pinches Posts: 2,840Administrator
    Nice job - well done Martin! Would you mind exporting and sharing your Cura profile here as an attachment? :-) Perhaps, you could share your other machine settings like gcode start/end too, if possible!
  • ProkktorProkktor Posts: 146🌟 Super Member 🌟
    No problem I will upload it, but only when its done.

    Atm I am working on tolerances again, I am at 0.35mm and thats bad i want to tune it to 0.2mm max.
    Also I found the "Number of slower layers" option which is great, since I start cooling late I need to print slowly in the beginning.


  • netzmarknetzmark Posts: 107🌟 Super Member 🌟
    So up to first 5mm do you print with the fan completely off or it's slowly increased after first layer to get max speed at 5mm?
    Note that changing bed temp from 25 to 60 changes its level for some 0.3mm.
  • Samuel PinchesSamuel Pinches Posts: 2,840Administrator
    edited November 2018
    I personally have the fan full on after the second layer. What you are suggesting sounds sensible.

    The aluminium on the bed is made by rolling out a thick block into a thin sheet. This means there is a lot of stress inside the material. When heated, this results in the bed warping. This means its important to level the bed when it is at the temperature you plan to print at.

    The solution for this is to used a cast aluminium bed. Unfortunately no cheap printer uses this.
    Post edited by Samuel Pinches on
  • netzmarknetzmark Posts: 107🌟 Super Member 🌟
    Yes I know about this aluminium issue. Just wanted to tell that bed temperature changing while printing can lead to printed object size and shape deformation.
    I use the same about the fan, just was curious how Prokktor does.
  • ProkktorProkktor Posts: 146🌟 Super Member 🌟
    edited November 2018
    No it slowly raises fans speed from 0 to 255 at 5mm, the fan starts spinning at  60/255.
    (I am using the blowhard 3000 design by Da Hai)
    Thats the beauty of "Number of slower layers", it slowly increases print speed at the same rate the fan increases its speed.
    The alternative is "Minimum Layer Time", but that is a constant over all layers.
    Still with a large print you need less slow layers, i found no way to make that automatic.
    Maybe a stack of "ChangeAtZ" scripts that change minimum layer time, no I fear Cura does not allow for that,

    Oh yes you are right, my bed only raises about 0.15 from 30 to 60 but that might be a problem.
    Small things I can print on the border because most of the bed warp is in the middle.
    I will try multiple ChangeAtZ and alter the bed temp in many steps.

    ATM I print at 85% extrusion and it still fails the .2mm test, that might indeed be the raising bed...
    Edit: No its at least not only that because that would only account for errors between 3mm and 4mm print height.

    I have more than enough bed adhesion at my current 60 C, so I will try a 50/55 C bed that drops by 5C every 1mm, that should take care of the problem.

    Thanks for the tips!

    Ah one more thing:
    I read an article about first layer height, it states the first layer height should be less then the normal layer height because then the same amount of plastic is squished in less space to get more bed adhesion.
    That indicates that "first layer height" does not influence flow rate which i find bewildering. Doubling Layer height and doubling print speed will of course double the flow rate... so how am I supposed to know which other options are not changing the flow rate automatically like I believe they would?
    Post edited by Prokktor on
  • netzmarknetzmark Posts: 107🌟 Super Member 🌟
    At so warped bed I'm not sure if not better to set first layer as 0.3... At least I did So last night and adhesion is good.
    Measuring laser temp says the top of the glass has some 10deg less than thermistor says. Worth to find and tune it in Marlin, or remember making print settings. So if you plan 50, it means 40 :-).
    Can you tell what and how you have fixed with Z mentioned in this post first line? I have impression that or my bed, or my x-axis or something with z has problem effecting 0.15mm in bed centre, hard to investigate it 100%. But definitely if I press right Z leading screw the nozzle comes down near 0.15, if pull it up nozzle same comes up. Like clearance on leading screw or motor axis. On left screw I can't see the effect so clear.
  • Samuel PinchesSamuel Pinches Posts: 2,840Administrator
    Ah no wonder I have been so confused.... DOH... the user icons are so similar I didn't realise :D sorry and thanks
  • ProkktorProkktor Posts: 146🌟 Super Member 🌟
    The top one is 98% flow the bottom one is 85% , the letters clearly become more visible the less extrusion I have. (ok I need a better camera...)
    They are at 10mm height, while the bed temp changed between 3 and 4mm.
    So I still believe I am on the right track :-)

  • ProkktorProkktor Posts: 146🌟 Super Member 🌟
    I think the Mesh takes care of the heat warping bed very good, the first layers are no problem as far as I can see.
    My Bed is actually 1 to 2 C hotter than the printer says, I measured with thermistor and infrared with similar outcomes,  my nozzle is about 1% to cold. Thats ok for me so I did not recalibrate.
    Sorry but I am unable to understand what you mean with the "fixed with Z" part.
    My bed middle goes down about .2mm when heating from room temp to 65C, I measured that by simply reading the output of G29 (S0). 
    Did you mean that?
  • netzmarknetzmark Posts: 107🌟 Super Member 🌟
    By bed goes up :-).

    This is what I've meant:
    "Hello,
    now that I corrected mit Z Axis height problems...."
  • ProkktorProkktor Posts: 146🌟 Super Member 🌟
    edited November 2018
    Ah yes there was a 0.2mm height difference between the mesh leveling and the actual printing height.
    So I used:
    G29 S4 Z-0.2
    M500
    To fix that^^
    Currently I leave it 0.1mm to high and correct by babystepping at every print. So I dont have to remesh when using a different bed temp.

    I am now at 80% flow and it passes the 0.2mm test, printing with 77% flow now^^

    Why is that thing overextruding so much:

    Idea: I saw youtube videos claiming it would be underextruding by 20% and I also saw videos claiming it would be overextruding bei 6% (thats a good one and probably unknown here so I link it)

    So the community firmware fixes the 20% underextruding, and since I had a 6% overextruding model, its now 26% overextruding?^^
    Post edited by Prokktor on
  • Samuel PinchesSamuel Pinches Posts: 2,840Administrator
    edited November 2018
    The problem is probably die swell. The steps per mm on the extruder axis should be fairly accurate (+/- <5%) after flashing the community firmware. The problem is a 0.4mm nozzle does not give you a 0.4mm extrusion output, more like ~0.43 depending on a few things. You do want some overlap between adjacent extrusion lines so the model has good strength, but I would suggest to maybe try playing around with that value rather than the flow rate.
    Post edited by Samuel Pinches on
  • ProkktorProkktor Posts: 146🌟 Super Member 🌟
    Ah interesting, hmm which is the value i should change than?
  • Samuel PinchesSamuel Pinches Posts: 2,840Administrator
    Try changing the nozzle diameter slightly. Maybe try a series of test prints, 0.41mm 0.42mm 0.43mm and 0.44mm and see which one looks best. I would go 100% flow.
  • ProkktorProkktor Posts: 146🌟 Super Member 🌟
    Ok at 77% it passes the .15mm test.

    I the tried .45 nozzle size and 100% flow: didnt even pass the 0.4mm test.

    Then I found this extruder calibration test:
    https://www.thingiverse.com/thing:2372705
    which prints in little over 10 minutes.

    I went down to 70% flow until i got the s'es pressed together.
  • netzmarknetzmark Posts: 107🌟 Super Member 🌟
    Great. Waiting for your profile settings so :-)
  • netzmarknetzmark Posts: 107🌟 Super Member 🌟
    Btw, what the slicer do you use? Hate java soft like Cura, old 15.04 version written in Python runs perfectly (speed) but an actual is fatal as for me...
  • ProkktorProkktor Posts: 146🌟 Super Member 🌟
    Yes its Cura, I dont like Java software either but now I want my Cura to work before I go and try other slicers.

    My problem at the moment is that I see signs of under extrusion  when I go to far below 80% flow especially in the top layer, but if i want to print  small gaps I need to go below 70% so they dont get filled with squished filament.
     Are there any other option to tackle one of those problems without worsening the other?

  • netzmarknetzmark Posts: 107🌟 Super Member 🌟
    I'm going crazy with both x-bearing clearance and bed warping. Making changes in profile I don't know if the new printed object changes are due to profile changes or mechanical. I see that changing temp 5deg the bed level changes 0.05mm.
    Started to use "slic3r prusa edition". Looks good.
    I'm newbe for 3D, but strange that for 0.4 nozzle of Prusa MK2 they ever declare the max height of the layer 0.35mm. Flow by default is 80%.

  • ProkktorProkktor Posts: 146🌟 Super Member 🌟
    If you use mesh leveling with enough points at the right temp, bed warping is irrelevant i think.

    I never thought about my bearings so far but they at least seem fine^^

    I thought about the die swell some more:
    Cura calculates filament steps by:
    Extrusion Width * Extrusion Height * Speed / Filament Width
    and extrusion width  is calculated from nozzle size and wall thickness.

    So when I changed nozzle size to 0.45 but leaving wall thickness at 0.8 he than tried 1 line of 0.8mm thickness which is probably not causign accuracy to improve^^ 

    I am now trying 0.45 nozzle size and 0.9 mm walls^^

  • ProkktorProkktor Posts: 146🌟 Super Member 🌟
    Oh i forgot the max height:
    I read many articles about that a few days ago, and they all state that max height is .7 or .8 times nozzle width.
    so with a .4 nozzle you can print .4*.3 mmΒ², thats 0.12mm2.
    Would you happen to have a 1mm nozzle you could print 1.0*0.75 that is 0.75mmΒ², which is more then 6 times as much filament^^
    (if the heating element is strong enough, I have no idea, but I will test 0.8 and 0.6mm nozzles once they arrive)
  • ProkktorProkktor Posts: 146🌟 Super Member 🌟
    edited November 2018
    So testing is nearing the end now.
    Widening the nozzle size in cura did not help in a meaningful way, I went up to 0.6mm at 0.5mm it might have been a very tiny improvement over 0.4, but that might have been random.
    So I went back to 0.4mm, 
    My tolerance problem stays. I settled for 80% flow, since there are next to no signs of under extrusion then. It passes only the 0.2mm test...
    Yesterday I printed three more detailed 28mm dnd figures and I actually learned something: All the temp towers are completely useless, I could spot no difference from 190 to 230 C there because they are to easy to print. With my figurine I saw that at 210 C the nozzle heated up small details during print and the looked frayed, also the high temp caused minor stringing. When printing at 190 C those problems where gone. Steep overhangs that normaly would need support actually look better with higher temps, but they still look bad so I would rather print the support then causing other problems with higher temps.
    The initial layer is printed at 210C because at 205C it does not stick^^
    Bed Temp: I found that more than 50% of the warping happens from 50C to 60C, so I now start out at 50C and lower the temp by 2C every 0.5mm, that does not cause any problems. My Final temp is 34C at 4mm.

    And here is the little guy:


    The halbert head was ONLY printable with "minimum layer time" in combination with "lift head"  so that after each layer the print head moves away from the halbert. Just slowing speed is of no use because if the nozzle remains in contact it heats up the previous layers and everything forms a long blob.

    I will perform some more tests today and then publish my profile.

    PS: I a still looking for a way to solve my tolerance vs underextrusion problem.

    PPS: The Knight actually looks much better then my first figure, but the harsh office light and zoom make every flaw visible. From 40cm away I cant even tell its printed with my eyes^^

    Thanked by 1Samuel Pinches
    Post edited by Prokktor on
  • Samuel PinchesSamuel Pinches Posts: 2,840Administrator
    @Prokktor great work and interesting findings!
  • netzmarknetzmark Posts: 107🌟 Super Member 🌟
    edited November 2018
    I have some idea about the warping.
    So the aluminium heat-plate is fixed in corners by the springed screws. The bed is not chaning the thickness but size during the heating. Because it is kept in corners must move the centre up or down. Glass is connected to the aluminium with clipses.
    What if we change the rules to opposite:
    - remove the heater
    - design corner holders connecting the glass with the springed leveling screws
    - make leveling the glass with screws
    - connect an aluminium heater to the glass with clipses.
    I mean the heater bed is not kept to the Y-guides but is only easy connected to the glass. The can easy change the size xy but maybe not Z.
    I'll try to check if the Z changes if the screws are completely released. Then it could make sense...

    Post edited by netzmark on
  • ProkktorProkktor Posts: 146🌟 Super Member 🌟
    Hmm it is probably easier to just put another layer on top of the whole thing, like a buildtak only thicker...

    But then I still dont know why the warping is such a big problem.

    Ok the underside of my prints is warped by 0.2mm max from one end to the other, and I have to make a new mesh leveling everytime I need to print at a different bed temperature. 
    The Mesh bed leveling takes 2 to 3 minutes, so I dont think I will change anything about the bed, apart from my insulation to conserve energy.

    What I will do is install TCM2XXX stepper drivers and probably a full metal hotend with direct drive.

  • netzmarknetzmark Posts: 107🌟 Super Member 🌟
    I like have everything stable and irritates me that the printed size is changing when I change temperature...

    TMC2208 in my nearest plans :-)
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