Jump to content
UltiMaker Community of 3D Printing Experts

Narrow fit parts: issues


knutselsmurf
 Share

Recommended Posts

Posted · Narrow fit parts: issues

I have an Ultimaker3, it prints nice but when I print some parts which must be combined later (narrow fit!) then these parts didn't fit at all.

Parts are allways too big.

 

Print PETG with 40mm/s, 245'C nozzle, 80'C bed.

 

Bedleveling calibrated.

Also tried calibrating the steps (X,Y, Z and extruder).  Used all kind of filament, Ultimaker brand or whatever: same results..

 

As long you print something which doesn't need to be printed very accurate then the printer is ok.

 

Is there somebody who have this same problem and nows how to fix it ?

 

 

  • Link to post
    Share on other sites

    Posted · Narrow fit parts: issues

    There has to be a clearance between the parts.

     

    If you slide a part into a 20MM hole the part going into it would have to be around 19.5MM in diameter and it would fit pretty snug, may need to be 0.4 or 0.3 MM smaller than the part it goes into but it does have to have a little bit of clearance.

     

  • Link to post
    Share on other sites

    Posted · Narrow fit parts: issues

    Layer lines, blobs, strings, hairs, ringing and thickening at corners, always cause inaccuracies. I usually make a couple of small test models to try which tolerances work best for a particular model feature. Depending on the required fit, I usually take between 0.1 and 0.5mm tolerance for my UM2-printers. Printing slow and in thin layers also helps.


    For example for inserting M4 nuts (which have a diameter of 7.0mm between flats for steel, and 7.2mm for nylon, in my inventory) into a 3D-printed cage, I made this test model with 7.2, 7.3, 7.4 and 7.5mm hex cages. Then I tried what worked best, and I used that for the real design. Steel nuts are hard to force into too small holes in a PLA model, but for nylon nuts it is easier.

     

    image.thumb.png.cc97a3b20f290085de92f39208528f7e.png

     

  • Link to post
    Share on other sites

    Posted · Narrow fit parts: issues
    15 hours ago, tinkergnome said:

     

    @geert_2  - you can modify the shape of the pocket a bit, makes assembling much easier and distributes forces a bit better:

     

    nut_pocket.thumb.PNG.a050911960b6a5dd86ad78c10c637712.PNG

     

    Thanks, good idea. I have seen the concept before (metrinch wrenches in shops), but never tried it in 3D-printing.

     

    Do you have a rule of thumb, or a formula, for designing the optimal curves? Or do you do it just visually and based on experience? This isn't a standard shape in my 3D-editor DesignSpark Mechanical, so I will have to draw it manually.

     

    This concept of "recessed corners" (I don't know a better description) could surely help to reduce the accuracy problems in corners due to ringing, thickening and rounding effects. Also in other designs. Maybe the original poster can also use this concept for a better fit?

     

  • Link to post
    Share on other sites

    Posted · Narrow fit parts: issues
    6 hours ago, geert_2 said:

    Do you have a rule of thumb, or a formula, for designing the optimal curves?

     

    I made a parametric sketch and used a radius that is equal to the wrench size (because it "looks right" 😏).  It turned out that it scales quite well for usual sizes of threaded nuts.

     

    I hope one can see it:

     

    nut_pocket_sketch.thumb.PNG.c7bb4a075615c8ccb603bb891436a7ad.PNG

     

    nut_pocket_detail.thumb.PNG.498d5b73058ef8d3556949a0adce912a.PNG

  • Link to post
    Share on other sites

    Posted (edited) · Narrow fit parts: issues

    Thanks for all your comments 😀

     

    After calibration of the x,y,z and e-steps i get now the accurate sizes 😀

     

    I found out that the z-steps are ok, but the others needs to be calibrated for every new rol of filament!!

     

    The steps can be changed in the firmware (.sjon file). 
     

    New problem: after I got a firmware update, this option is not available anymore, or maybe the setting file is moved to another place. (I will look for a fix this weekend)

     

    Anyway: I have created a calibration part and a howto on: www.thingiverse.com/askmurphy 

     

    If you like, print the test object and check your step-calibration (you can use the calibration spreadsheet on the above page) and show your results here.

     

    The Ultimaker3 is a nice printer but for accurate prints it’s not good at all if you don’t calibrate the printer. The 2.85mm filament is one of the main reasons, the print accurate error is much higher then with a 1.75mm filament..

     

    If you ask Ultimaker about this: you get default answers, useless.

     

    If you are interested, i can place another calibration part here, narrow fit parts..

    Edited by knutselsmurf
  • 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

      • Here it is. The new UltiMaker S7
        The UltiMaker S7 is built on the success of the UltiMaker S5 and its design decisions were heavily based on feedback from customers.
         
         
        So what’s new?
        The obvious change is the S7’s height. It now includes an integrated Air Manager. This filters the exhaust air of every print and also improves build temperature stability. To further enclose the build chamber the S7 only has one magnetically latched door.
         
        The build stack has also been completely redesigned. A PEI-coated flexible steel build plate makes a big difference to productivity. Not only do you not need tools to pop a printed part off. But we also don’t recommend using or adhesion structures for UltiMaker materials (except PC, because...it’s PC). Along with that, 4 pins and 25 magnets make it easy to replace the flex plate perfectly – even with one hand.
         
        The re-engineered print head has an inductive sensor which reduces noise when probing the build plate. This effectively makes it much harder to not achieve a perfect first layer, improving overall print success. We also reversed the front fan direction (fewer plastic hairs, less maintenance), made the print core door magnets stronger, and add a sensor that helps avoid flooding.
         

         
        The UltiMaker S7 also includes quality of life improvements:
        Reliable bed tilt compensation (no more thumbscrews) 2.4 and 5 GHz Wi-Fi A 1080p camera (mounted higher for a better view) Compatibility with 280+ Marketplace materials Compatibility with S5 project files (no reslicing needed) And a whole lot more  
        Curious to see the S7 in action?
        We’re hosting a free tech demo on February 7.
        It will be live and you can ask any questions to our CTO, Miguel Calvo.
        Register here for the Webinar
          • Like
        • 10 replies
      • UltiMaker Cura 5.3.0-Alpha 🎄 Tree Support Spotlight 🎄
        Are you a fan of tree support, but dislike the removal process and the amount of filament it uses? Then we would like to invite you to try this special release of UltiMaker Cura. Brought to you by our special community contributor @thomasrahm
         
        We generated a special version of Cura 5.2 called 5.3.0 Alpha + Xmas. The only changes we introduced compared to UltiMaker Cura 5.2.1 are those which are needed for the new supports. So keep in mind, this is not a sneak peek for Cura 5.3 (there are some really cool new features coming up) but a spotlight release highlighting this new version of tree supports.  
          • Like
        • 17 replies
      • 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
        • 14 replies
    ×
    ×
    • Create New...