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Prints not sized correctly


dudical26

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Posted · Prints not sized correctly

Hello,

 

I have an ultimaker 3 and I'm using the default settings in Cura (3.4.1)

I'm designing in TinkerCad.  

My prints are not properly scaled to measurements in tinkercad.  For example a 10mm cube is off by as much as 5% or more. 

I've read conflicting information on how to adjust this and I'm not sure what's the best way to fix this problem. 

I'd appreciate any help from the community, thank you

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    Posted · Prints not sized correctly

    I could but I would need to scale each axis differently, not sure if that's advisable. 

     

    When I make a 10mm cube I get a result that's

    X Axis - 10.15mm

    Y Axis - 10.22mm

    z Axis - 9.94mm

     

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    Posted · Prints not sized correctly

    Hi and welcome here!

     

    Ok, there are several things you could check: 

    1. Where do you measure your cube? Because don't measure the vertical corners, they could be bulged out and your measurement is wrong.
    2. Print slow, about 25-30 mm/sec and set all speeds (there should be 6) all to the same speed.
    3. Turn off acceleration and jerk control in Cura
    4. Uncheck infill before walls
    5. Check setting "Slicing tolerance" and try inclusive/exclusive settings instead of middle
    6. Check your axles if they have play (check the UM site for instructions)

    Beware that some of the above options are just to get dimensional accuracy as good as possible, but you will get not so nice surfaces and walls. Both is not possible, so you have to find a compromise between accuracy and beauty that fits your needs.

     

    General I would say, that your measurements are not so bad, more less normal. You can get a bit closer with the settings above, but don't expect to have 100% accuracy in all 3 axis. A 3D printer is not a CNC mill and due the process, melting plastic which shrinks at cooling you cannot get 100% the excepted values.

     

    Additionally try the search function about "dimensions accuracy" for a lot of more informations. We have the last weeks a lot of threads like this. My suggestions above are roughly a summary.

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    Posted · Prints not sized correctly

    OK if you have not done so already, you should check the measurements in Cura to ensure they exactly replicate the measurements in Tinkercad.

     

    On the X/Y axes; afraid I have to disagree with @Smithy, who does have some good stuff above, but if you are doing engineering stuff and dimensional accuracy is vital then your measurements are poor. You should be able to better 100 microns easily and quite frankly 50 microns too. I can better 20 microns but have never been able to do so  consistently, so in our T&Cs we guarantee 50 microns but prefer 100 microns as that allows us to work faster and cheaper.

     

    You need to research and I mean hours and hours of testing; which filament(s) gives you the best results. We go to one of two filaments if dimensional accuracy is tantamount. Play, in a disciplined manner, with your Cura settings to establish what produces the sweet spot and then stick to that. I had always had the strong view that slower was better. But a month back I printed something for myself, used 60mm/s and was really surprised at how accurate it was. So I now have to find a few days of free time, test and test whilst re-evaluating my views.

      

    Then of course you have e-steps. I am guessing you have  pretty new printer with not that many hours of use, so mechanical wear and tear should not be an issue. I am sure I read somewhere that part of Ultimaker's QA process is checking the e-steps; which infers that for any given printer the manufacturing process, when everything is pulled together, can result in performance differences. I may not be 100% correct on that but I will add that when I first got my printer I spent a lot of time focused on dimensional accuracy and everything was good.  Six months ago, following a period of 18 months(?) when I did not need to worry about it, we got a job where accuracy was vital. On the first run the dims were appalling. That was when I taught myself how to recalibrate e-steps and it is all sweet again following that work.

     

    The z-axis is a bit different. Additionally you have your nozzle to bed distance set during your bed levelling. If you like to have your filament really squashed down to get great adhesion well your first layer will not physically be 0.300.Your Z-axis measurement is your most accurate and it is shorter not longer, quite possibly resulting from your z-offset. You may find that if you increase your gap marginally you may improve on that 60 micron variance. But you are pretty reasonable so be careful otherwise you will make it worse

     

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