Jump to content
Ultimaker Community of 3D Printing Experts

Wavy pattern appears along Z axis of print


ivanchaos
 Share

Recommended Posts

Posted · Wavy pattern appears along Z axis of print

 

Hi Everyone:

 

I've encountered a rather strange problem: My print results appears to have wavy pattern along their z axis. I know it sounds like a z rod problem but I've checked more than ten times and ruled it out.

 

Another thing about this phenomenon is that somehow it's related to print speed:

test print

 

 

It bothering me since the wavy pattern is visually noticable and to be honest very obvious...like this one:

naked women bust (with wavy pattern along z axis)

Any ideas about this guys? Any help would be much appreciated!

 

  • Link to post
    Share on other sites

    Posted · Wavy pattern appears along Z axis of print

    That the lines are further apart as the speed goes up makes me think temperature fluctuations. Maybe take a look at the temperature graph and see if it matches the ridges?

     

  • Link to post
    Share on other sites

    Posted · Wavy pattern appears along Z axis of print

    Another idea is to check your filament tension. Maybe wavy pattern corresponds to the oscilating movement of the filament spool while unrolling. With too much tension this could affect the flow rate.

     

  • Link to post
    Share on other sites

    Posted · Wavy pattern appears along Z axis of print

    That the lines are further apart as the speed goes up makes me think temperature fluctuations. Maybe take a look at the temperature graph and see if it matches the ridges?

     

    Thanks for the reply! I suspected that, too. So I made a test print and tuned temp from 210 down to 190, but no luck...

     

  • Link to post
    Share on other sites

    Posted · Wavy pattern appears along Z axis of print

    Another idea is to check your filament tension. Maybe wavy pattern corresponds to the oscilating movement of the filament spool while unrolling. With too much tension this could affect the flow rate.

     

    Hi Nicolinux, I checked the filament spool, the tension needed for unrolling it is very subtle, pretty much sure it's not the reason...

     

  • Link to post
    Share on other sites

    Posted · Wavy pattern appears along Z axis of print

    Looking at your picture again, I am pretty sure it is somehow related to the fluctuations in the flow rate. There are wider slices followed by thinner ones. So the nozzle pushes out variable amounts of filament every few layers. And although variable the changes are still recurring.

    Maybe the connection between the z-stage and the acrylic bed is a bit loose. Maybe one of the springs got stuck and it allows the bed to move slightly.

     

  • Link to post
    Share on other sites

    Posted · Wavy pattern appears along Z axis of print

    This is very bizarre. This experiment where you printed slower and faster blows out all my theories (filament gets wider and skinnier, Z screw issues, slicer issues). Maybe you should repeat that experiment in reverse in case the problem had nothing to do with the speed and it was a coincidence.

    Anyway, assuming it really changes with speed the only thing I can think of is temperature. The time it takes to go from 210 to 190 is much too fast to make any difference in the pattern.

    The problem is most likely related to flow of plastic. It's extruding less in the skinny sections and more in the fat. Temperature cycles explain this perfectly. Print using the cura window instead of the Ulticontroller and look at the graph of the temp. Time the bumps/waves in the temperature graph and also time how much time it takes to print from one "bulge" on your part to the next. See if they roughly agree.

    Also to eliminate fan issues you might want to turn it off as an experiment.

    I would recalibrate the PID values. Actually I would get pronterface and figure out what the current values are. Pronterface is free. When it first connects to your UM it prints out lots of values including the PID values. You can see my values in this screen shot:

    Pronterface Screenshot

     

    Oscillation is very common in PID controllers. Larger values of P or I increase oscillations. D decreases. I wouldn't touch D though but it is quite safe to cut P or I (or both) in half. The only downside is it may take a little longer to heat up but probably not. Or you can issue the M303 to recalculate the values:

    M303 S210

     

    210 is the temp to calcluate the values at. Default is 150C and 210C will give you slightly better results (not much different though).

     

  • Link to post
    Share on other sites

    Posted · Wavy pattern appears along Z axis of print

    I've had this and I'm pretty sure it is caused by a combination of temperature and perhaps particular fibre type. I've been printing at 220 degrees with some Faberdashery fibre and getting good results, although my layers were sometimes a bit uneven.

    Today I put in some ColorFabb fibre and used the same gcode with very uneven results. At 220 the ColorFabb PLA seemed to be a lot more runny and this made it harder for the printer to control how the layers were laid down.

    I dialled the temperature down to 200 and printed again with much nicer results. I started using higher temperatures in the first place to improve adhesion to the base, but 200 sticks fine and I'm getting much smoother layers.

    I'd advise you to drop the temperature as low as you can, I reckon that will solve your problem.

     

  • Link to post
    Share on other sites

    Posted · Wavy pattern appears along Z axis of print

    But I really doubt that this is caused because it's too hot. I don't see this on my prints and I tend to oscillate between printing fast at 240C and slow at 190C.

     

  • Link to post
    Share on other sites

    Posted · Wavy pattern appears along Z axis of print

    Also the wavy pattern is way too regular to be just related to filament issues. I doubt that he has some weird filament where the diameter changes every few inches.

    Oh wait... That's another thing to check. Maybe the filament is the culprit.

     

  • Link to post
    Share on other sites

    Posted · Wavy pattern appears along Z axis of print

    That's another thing to check. Maybe the filament is the culprit.

     

    It can't be. Look at the first photo again. I already tried to explain that it can't be the filament.

     

  • Link to post
    Share on other sites

    Posted · Wavy pattern appears along Z axis of print

    This is very bizarre. This experiment where you printed slower and faster blows out all my theories (filament gets wider and skinnier, Z screw issues, slicer issues). Maybe you should repeat that experiment in reverse in case the problem had nothing to do with the speed and it was a coincidence.

    Anyway, assuming it really changes with speed the only thing I can think of is temperature. The time it takes to go from 210 to 190 is much too fast to make any difference in the pattern.

    The problem is most likely related to flow of plastic. It's extruding less in the skinny sections and more in the fat. Temperature cycles explain this perfectly. Print using the cura window instead of the Ulticontroller and look at the graph of the temp. Time the bumps/waves in the temperature graph and also time how much time it takes to print from one "bulge" on your part to the next. See if they roughly agree.

    Also to eliminate fan issues you might want to turn it off as an experiment.

    I would recalibrate the PID values. Actually I would get pronterface and figure out what the current values are. Pronterface is free. When it first connects to your UM it prints out lots of values including the PID values. You can see my values in this screen shot:

     

     

    Oscillation is very common in PID controllers. Larger values of P or I increase oscillations. D decreases. I wouldn't touch D though but it is quite safe to cut P or I (or both) in half. The only downside is it may take a little longer to heat up but probably not. Or you can issue the M303 to recalculate the values:

    M303 S210

     

    210 is the temp to calcluate the values at. Default is 150C and 210C will give you slightly better results (not much different though).

     

    Hi gr5:

    I've ran a test using Pronterface, the chart is exactly the same as yours, so I guess it's not the problematic spot?

     

    I've had this and I'm pretty sure it is caused by a combination of temperature and perhaps particular fibre type. I've been printing at 220 degrees with some Faberdashery fibre and getting good results, although my layers were sometimes a bit uneven.

    Today I put in some ColorFabb fibre and used the same gcode with very uneven results. At 220 the ColorFabb PLA seemed to be a lot more runny and this made it harder for the printer to control how the layers were laid down.

    I dialled the temperature down to 200 and printed again with much nicer results. I started using higher temperatures in the first place to improve adhesion to the base, but 200 sticks fine and I'm getting much smoother layers.

    I'd advise you to drop the temperature as low as you can, I reckon that will solve your problem.

     

    Hi Robmiles:

    I tried the lower temp trick til the machine underextrude and the print fail...but no luck.

     

    Looking at your picture again, I am pretty sure it is somehow related to the fluctuations in the flow rate. There are wider slices followed by thinner ones. So the nozzle pushes out variable amounts of filament every few layers. And although variable the changes are still recurring.

    Maybe the connection between the z-stage and the acrylic bed is a bit loose. Maybe one of the springs got stuck and it allows the bed to move slightly.

     

    Hi Nicolinux:

    I've checked and re-assembled the z-stage with z-rod connection a dozen times, they are tight and secure. Besides if the problem do relate to z-system, my re-assembling should make the rest results vary, but sadly every individual test are identical.

     

  • Link to post
    Share on other sites

    Posted · Wavy pattern appears along Z axis of print

    What speed and layer height are you printing at? Given that everything else has been ruled out, my guess would be that it's related to head pressure; the pressure builds up, so the filament starts to slip causing under-extrusion; the pressure evens out, the filament grips again, pressure builds back up and the cycle repeats.

     

  • Link to post
    Share on other sites

    Posted · Wavy pattern appears along Z axis of print

    so the filament starts to slip causing under-extrusion;

     

    That would make sense but he has the problem even at 10mm/sec! And it's not any better at 10 then at 20. No -- I think it's temperature related.

    Please please - use Cura - set the temp to 180C and let it sit for 20 minutes. Come back and look at the graph. This was what I wanted you to do the first time. This is what Robert suggested. This was the VERY FIRST SUGGESTION and it's the only one that makes sense to me at this point.

    I spent a lot of time thinking about your issue. Did you spend much time reading all the responses and thinking about them?

     

  • Link to post
    Share on other sites

    Posted · Wavy pattern appears along Z axis of print

    Ah yes, I forgot that he was using very low speeds. I wonder if that's the problem somehow... the nozzle is dwelling on the print, reheating it, causing it to soften and sag away from the nozzle a bit, reducing the heating... you can see on the sides of the print that it is bowing out.

    Printing faster might alleviate the reheat, but then you get into too little layer cooling issues. I'd suggest trying printing several test pieces at once, at the same speeds, and see if that improves the quality.

     

  • Link to post
    Share on other sites

    Posted · Wavy pattern appears along Z axis of print

    A static test like that could be good for keeping variables out but I don't know if letting it just sit there is going to make the temperature sway much. Stagnant air and no cold material makes it pretty easy to keep a constant temperature, add in fans and cold material and it might start to struggle more and produce dips.

    edit: This was in response to gr5, illuminarti snuck in between. I really need to stop doing more than one thing at once...

     

  • Link to post
    Share on other sites

    Posted · Wavy pattern appears along Z axis of print

    Hi Everybody:

    After trial and errors, I finally found the source --- it's the vibration caused by the snail fan underneath! Now who could've thought of that.....

    Thanks for all your suggestions guys!

     

  • Link to post
    Share on other sites

    Posted · Wavy pattern appears along Z axis of print

    Wow, that's really weird. And I bet many others might have this problem too without ever finding the cause.

     

  • Link to post
    Share on other sites

    Posted · Wavy pattern appears along Z axis of print

    What? The fan on the electronics board caused ... what? Caused the platform to wiggle? What was the solution? I hope you didn't just unplug it!

     

  • 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
        • 11 replies
    ×
    ×
    • Create New...