Jump to content

UM2 Accuracy

Recommended Posts

Posted · UM2 Accuracy

Good Afternoon fellow Ultimakers,

I have a question for the wise owls out there.

I have been printing some fairly close tolerance parts on my UM2 but I am finding that they are not printing to the correct sizes.

Now I expect some shrinkage from PLA but the dimensions are smaller than I would expect.

On my UM Original i can set the 'steps per mm' on the Ulticontroller but I have had a look on the UM2 and I cannot find the same!

Am I missing something?

I don't really want to have to start scaling my models to compensate this deviation.




  • Link to post
    Share on other sites

    Posted · UM2 Accuracy

    No, it's not available in the User Interface on the UM2, and since you can't include start gcode either with Ultigcode, there's no easy way to do it.

    You could change your gcode type to Reprap/Marlin, which would allow you to include your own start gcode, and then add the relevant gcode commands in the start gcode (along with the necessary codes for homing, heating etc).

    Alternatively, you can build your own version of Marlin, and change the steps setting in the configuration.h file.

    All of that said, the steps-per-mm should be a fixed function of the components - pulley teeth pitch and diameter. So the default setting should be exactly correct, by definition.

    How large are the errors that you are seeing?


  • Link to post
    Share on other sites

    Posted · UM2 Accuracy

    If your print bed is at 75C, the bottom 5mm will be very distorted so keep that at 60C instead.

    PLA is expected to shrink about .3% once it gets below the glass temp and it shouldn't shrink much before then. That is what typical injection mold people use as a rule of thumb I believe - .3%.

    There are many other factors and they are different depending on PLA additives (coloring), temperature and printing speed.

    So even though you don't want to scale your model, I think it's worse than that. For example vertical cylindrical holes shrink much more than say cubes. And the Z axis shrinks much less than X or Y axis. And lower levels (close to the hot bed and where fan wasn't on at full) tend to shrink differently also.

    So you might need to add a taper at the bottom 5mm to compensate for something.

    Most people who need very tight tolerances just print everything twice but as you learn how much things need adjusting for your given filament and print settings you get very good at predicting the model changes ahead of time.


  • Link to post
    Share on other sites

    Posted · UM2 Accuracy

    Thanks fellas,

    Mucking about with the g-code scare the willies out of me!

    I guess I will have to start looking at scaling my models.

    If PLA does shrink around 0.3% that would be more or less in line with the shrinkage I am getting.

    Thanks for your help.



  • Link to post
    Share on other sites

    Posted · UM2 Accuracy

    Mucking about with the g-code scare the willies out of me!


    You mean the STL?

    If you are designing stuff in CAD then all you have to do is measure the result after you print it and then adjust the high tolerance areas a little bigger as needed. If you are printing out someone else's "high tolerance" part then I don't know what you can do other than scale (the x,y only) in Cura.


  • Link to post
    Share on other sites

    Posted · UM2 Accuracy

    Seriously, messing around with the steps per mm is wrong. We did careful calculations and measurements to ensure that the 80steps/mm is the correct value for the UM2.


  • Link to post
    Share on other sites

    Posted · UM2 Accuracy

    GR5, a bit of both really, the file i was having troubles with is now all sorted thanks.

    Daid, No worries, taking all things into account I am very happy to leave my UM2 alone, well apart from the feeding issues, but thats another matter (which I know will be sorted soon)


  • 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

      • 🎄✨ Thingiverse Tree Ornament Challenge! ✨🎄
        We've been running a Tree Ornament Challenge with a chance to win an UltiMaker S3 or colorFabb filament.
        Design a 3D printable tree ornament and join our festive challenge on Thingiverse. 🎁✨

        📆 Submission Deadline: December 22
        🏷️Tag your designs with Holidays2023

        Click here to join and check out the over 300 other amazing designs

        How to Enter
        Design an Ornament
        Create a 3D printable tree ornament that captures the magic of the winter season. Think snowflakes, sleighs, reindeer, cozy mittens, or anything that embodies the joy of the holidays. Upload to Thingiverse
        Share your masterpiece on Thingiverse and add the tag Holidays2023. Don't forget to include a captivating description and images that showcase your design from different angles. Submit by December 22
        All entries must be submitted by December 22nd to be eligible for consideration.
          Entering a new design
        Entering an existing design
        Winning designs should:
        Be original Creations
        Your designs should be original works, avoiding the use of others' intellectual property without permission. Include STL Files
        Each submission must include at least one STL file for 3D printing. Showcase a Completed Print
        Provide at least one photograph featuring a completed print of your design. Include Documentation
        Share the creative journey! Include documentation of your design process, giving us a peek behind the scenes. For example, show a screenshot of the model in your design program. Use the Tag Holidays2023.
        Use this tag to ensure your entry is counted in the Tree Ornament Challenge. Be submitted after October 1st, 2023
        Ensure your design was uploaded to Thingiverse after October 1st, 2023. Adhere to Submission Guidelines and Terms of Service
        Make sure your submission aligns with our guidelines and Thingiverse's Terms of Service.  
        Good luck 🎉
        • 1 reply
      • 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
      • Ultimaker Cura 5.6 stable released
        Cura now supports Method series printers!
        A year after the merger of Ultimaker and MakerBotQQ, we have unlocked the ability for users of our Method series printers to slice files using UltiMaker Cura. As of this release, users can find profiles for our Method and Method XL printers, as well as material profiles for ABS-R, ABS-CF, and RapidRinse. Meaning it’s now possible to use either Cura or the existing cloud-slicing software CloudPrint when printing with these printers or materials
        • 14 replies
    • Create New...