Jump to content

Asymmetric prints


Nicolinux

Recommended Posts

Posted · Asymmetric prints

Hi,

I have just finished building my Ultimaker and after printing the obligatory Ultimaker Robot, I tried another small print (trilobite - thing:28259). I didn't touch any settings (except setting the layer height to 0.2). The print seems asymmetric and skewed to the left side. The left "fishbones" are thicker towards the tip. What could be the cause? The object was positioned in parallel to the front of the machine so it seems to be related to the y axis.

Or maybe it is a bed leveling issue (although I leveled the bed right after finishing the build).

Images:

http://www.flickr.com/photos/nic0linux/9549271568/in/photostream/

http://www.flickr.com/photos/nic0linux/9546481407/

Ultimaker Robot:

http://www.flickr.com/photos/nic0linux/9546480545/

Thanks,

Stefan

 

  • Link to post
    Share on other sites

    Posted · Asymmetric prints

    Are your motors pushed down as far as you can get them to tension up the short pullys? As Nick said, this is usually caused by one of the short pullys being loose. If the motor screws are not tight enough the motors can creep up and loosen those belts on you.

    Cheers,

    Troy.

     

  • Link to post
    Share on other sites

    Posted · Asymmetric prints

    I would also make 100% sure that there isn't any aluminum swarf stuck in the bottom of the threaded pulley holes. No matter how hard you tighten the screws, if there is material down there, the pulleys will slide.

     

  • Link to post
    Share on other sites

    Posted · Asymmetric prints

    Looks like backlash causing positional inaccuracy. Check the belt tensions - especially the short ones.

  • Link to post
    Share on other sites

    Posted · Asymmetric prints

    @CodeMaven and illuminarti: Alright, I guess that was it. I followed the advice from the wiki and didn't overdo the tightening of the motor. Well I guess sometimes it is ok to overdo it. I pushed the motor(s) down and tightened the four screws. To be honest - I don't like this approach. Over screw holes will wear out and will allow for more and more play. I am thinking about another approach. Maybe something involving a small bearing that pushes against the short belts from the side. The position of the bearing should be adjustable so one can control the amount of pressure that is exerted on the belt. What do you think? I know about thing:34785 - maybe this is a better solution because it protects the panel from "abusive screwing".

    @Nick: I had already disassembled the x/y rods and pulleys two times in a row. I guess/hope that everything that was stuck in the pulleys would have fallen off by now.

     

  • Link to post
    Share on other sites

    Posted · Asymmetric prints

    I have my Ultimaker for almost over a year and it has been used quite a lot.

    I never had issues with motors getting loose very easy, or screw holes wearing off.

    I do have washers under the screws, maybe that is a good idea if you don't have it already.

    Except for the previous mentioned tips, you could also have checked your axis for alignment.

    If it would be off, or the pulleys would not be parallel with the axis, this could also create more resistant when

    the printhead will approach the frame/sides.

     

  • Link to post
    Share on other sites

    Posted · Asymmetric prints

    I have washers on the outside and the inside of the panel (and since I used the short motor screws I had to shorten the plastic spacers - stupid idea, I could have used longer screws instead but I didn't know how many screws would be left over). I have also checked the axis alignment - it is alright (according to the provided "measurement sticks").

     

  • Link to post
    Share on other sites

    Posted · Asymmetric prints

    I've had my Ultimaker for over 2 years now... Way back when I got it I had this problem with the short belts... But once I moved the motors and tightened the screws I never had an issue after that. You don't have to force the screws until they strip, but just make sure that they are nice and (hand) tight. Do not use an electric screwdriver or anything like that. Once they're on there good they will not slip.

    Cheers,

    Troy.

     

  • Link to post
    Share on other sites

    Posted · Asymmetric prints

    Alright, thanks CodeMaven. The motors are tight and I won't bother them for now. I have aligned the aligned the axis (again and again) and tightened the pulleys down.

    One more issue to go and I hope I will finally start to get decent prints:

    http://umforum.ultimaker.com/index.php?/topic/2716-cannot-lower-bed-to-reach-endstop

     

  • Link to post
    Share on other sites

    Posted · Asymmetric prints

    ws I had to shorten the plastic spacers

     

    oh no! Don't do that. Too late I guess. Those spacers aren't long enough as it is. I had to add washers under them because the X stepper short belt was hitting the back of the UM.

    Please watch your printer while it is printing and look at the short belts. Especially the X belt. If it is hitting the wood it is really hard to tell. You can tell this is happening because the belt kind of twists - and it twists a different direction each time the X stepper changes direction. If this is happening you need to add more washers (and possibly longer screws?).

    You could potentially throw away the plastic spacers and use the wooden ones instead. The only downside is your UM will be much more noisy.

    My screws just barely reach the X motor. I didn't try longer ones.

     

  • Link to post
    Share on other sites

    Posted · Asymmetric prints

    Thanks for the warning. I made sure that the short belt doesn't touch the wooden panel. That's why I didn't follow the advice from the assembly instructions and placed the pulley quite close to the motor.

     

  • 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
    • Our picks

      • Introducing Universal Cura Projects in the UltiMaker Cura 5.7 beta
        Strap in for the first Cura release of 2024! This 5.7 beta release brings new material profiles as well as cloud printing for Method series printers, and introduces a powerful new way of sharing print settings using printer-agnostic project files! Also, if you want to download the cute dinosaur card holder featured below, it was specially designed for this release and can be found on Thingiverse! 
          • Like
        • 10 replies
      • S-Line Firmware 8.3.0 was released Nov. 20th on the "Latest" firmware branch.
        (Sorry, was out of office when this released)

        This update is for...
        All UltiMaker S series  
        New features
         
        Temperature status. During print preparation, the temperatures of the print cores and build plate will be shown on the display. This gives a better indication of the progress and remaining wait time. Save log files in paused state. It is now possible to save the printer's log files to USB if the currently active print job is paused. Previously, the Dump logs to USB option was only enabled if the printer was in idle state. Confirm print removal via Digital Factory. If the printer is connected to the Digital Factory, it is now possible to confirm the removal of a previous print job via the Digital Factory interface. This is useful in situations where the build plate is clear, but the operator forgot to select Confirm removal on the printer’s display. Visit this page for more information about this feature.
          • Like
        • 0 replies
    ×
    ×
    • Create New...