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Solved Model Tolerances

Discussion in 'General Questions' started by Ryan TeGantvoort, Jun 1, 2016.

?

Model Fit Tolerance?

  1. 1%

  2. 5%

  3. 10%

  4. 15%

  5. 20%

  6. 25%

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  1. 3D Printer Man

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    Okay, sorry.
     
  2. KTMDirtFace

    KTMDirtFace Well-Known Member

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    What?

    I don't understand most of your posts lol
     
    Ryan TeGantvoort likes this.
  3. Ryan TeGantvoort

    Ryan TeGantvoort Active Member

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    Why can't everyone do this?! Anything I upload will have SolidWorks Files, STEP and IGS. Should be able to open in most 3D CAD programs. I hate all the OpenScad stuff on Thingiverse.
     
    KTMDirtFace likes this.
  4. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    I wish. It would make Thingiverse much more useful.
     
  5. KTMDirtFace

    KTMDirtFace Well-Known Member

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    It would for sure. But all the artists at my work do mesh modeling. I had a guy at work give me a .obj that had like a BAZZILLION triangles for a simple holder to hold his sprinkler system computer.. The file was so ridiculously huge. ( he does everything in ZBrush ). Even with those bazilion triangles the edges and stuff were not perfect like a CAD/Nurbs model.

    So yea basically that was damn near as bad as an .STL for me to modify lol.
     
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  6. WheresWaldo

    WheresWaldo Volunteer ( ͠° ͟ʖ ͡°)
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    This is exactly what happens when you let graphics artists make 3D models for prints, they use applications like ZBrush, Blender or whatever. Politely tell them to stop. Graphics artists are not usually capable of building something that can be printed without a lot of work. I stopped trying to modify models that are only .obj or .stl. I spend a lot less time recreating them in Fusion 360 than editing the originals.

    The following is a true story. I used to build custom homes in Eugene, OR. We worked with one of the premiere architects ever to come out of the UoO School of Architecture. She would give use plans that were very elaborate. The problem was that in almost every plan there was a section drawn that could simply never be built. We finally got her to stop adding those sections and leaving them as conceptual drawings that would be specifically referenced as "as built". We would build it, then tell her how it was built then she would modify the drawings appropriately. My dad and I both agreed at the time, that anyone designing a structure and claiming to be an architect needed to spend a semester actually building the crap they designed just to teach them to design what can be built. The same rule applies to graphics artists trying to design real world items.

     
  7. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Or, failing that, just put the beat-down on them :)

    Seriously though, don't go there.

    One thing I learned (painfully) was that 3D modeling for PRINTING is different than 'normal' 3D modeling. Normal 3D modeling seemed to fall into the artistic or engineering camps.

    For 'artistic stuff is is all about how it looks and for engineering stuff it is all about accuracy... 3D printing is closer to the second one, but not exactly ... I can do infinite tolerances on the model, the printer is less forgiving. Taking an 'artistic'model and getting it printable can be a headache (or impossible).
     
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  8. MindTorque

    MindTorque New Member

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    I rather like OpenSCAD... When files from that are included I feel like I'm actually learning something. :)

    As for tolerances, I've managed to do some experimentation these past few days to investigate how the error varies with hole size. At first glance it appears that a decent degree of programmatic correction for such is possible, check out the following graph:
    SizingHoles.png
    At least it's not a polynomial...
     
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  9. WheresWaldo

    WheresWaldo Volunteer ( ͠° ͟ʖ ͡°)
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    @MindTorque Interesting find.
    OpenSCAD, yeah learning math/programming. I think that most manufacturing concerns as well as the vast majority of CAD modelers prefer a less programmatic approach to modeling. I know I do. And since many visual modeling apps have a timeline feature it is easier to go back and forth through the features you have modeled in, seeing immediate results.
     
  10. MindTorque

    MindTorque New Member

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    @WheresWaldo You do have a point, the programmatic approach isn't for everyone...

    Having said that, for models which are subject to substantial customization I think the programmatic approach is a good one. If you're interested in quick turnaround for specific cases one only needs to specify the relevant parameters at the top of the file; a quick edit of a few numbers and *POOF* you've generated one tailored to the particular instance. For complex items this could be a serious timesaver if the model was well-written in the first place.

    Oh, for the OpenSCAD aficionados... I should have mentioned in the initial post that I set $fn = 400 (which is the Resolution); for those who don't already know small circles are more like polygons if you fail to specify that or one of the others ($fs for fragment size or $fa for fragment angle).

    Now I need to further quantify how things scale on my Z-axis heh....
     
  11. WheresWaldo

    WheresWaldo Volunteer ( ͠° ͟ʖ ͡°)
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    The key but it is not usually the norm.
     
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  12. KTMDirtFace

    KTMDirtFace Well-Known Member

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    Ha I was born there! ( and will never go back lol )

    I should try openscad, I have a math degree and am a programmer. so Accurate stuff is up my alley..I'm far from an artist..and is why I'm really liking Nurbs ( MOI, Rhino, Fusion360 ) type modelers. I can accuratly draw what I want. In college I did some open GL programming and had to draw shapes all by code..so I could probably do openscad. But MOI/Fusion360 is good enough for me.

    Now if I was making a video game character.. I imagine nurbs modeling would kinda suck. But also that kinda thing doesn't usually print to well anyway on FDM

    I am terrible at 3d modeling anyway just getting into it since having 3d printers.
     
  13. WheresWaldo

    WheresWaldo Volunteer ( ͠° ͟ʖ ͡°)
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    @KTMDirtFace I left almost 25 years ago and despite it being one of the most beautiful places in the world I vowed never to return. But, I recently had to promise my wife that we would go back as both our parents are aging, some not so well and all of our families live in either Eugene or Springfield.

    If you were a programmer then you might like OpenSCAD. One of my major complaints with it is that the only output format (other than the actual model source file) is STL and if you can't modify the SCAD file then your f***ed. Also even though everything is parametric most people do not declare all their variables at the beginning or they make explicit declarations so you have to hunt through all the code to change stuff. A second issue I have is that there is no timeline feature so if you make a change in the middle and it affects something adversely in the latter part of the model you can't/won't see it until you render the model. You already know that with Fusion 360 if you go back in the timeline and make a change you can see it affect the model immediately. To take @MindTorque's example of using the Fn function to declare how fine a grain circles are (which aren't circles at all but rather polygons as OpenSCAD does not implement Arcs) most of the programs I have downloaded declare the number of segments at the time of circle creation rather than making it a parameter at the beginning of their source code. Then they only upload the STL to places like Thingiverse or YouMagine.
     
  14. KTMDirtFace

    KTMDirtFace Well-Known Member

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    I should at least try it. I don't think I would use it over fusion 360 though lol.

    I left Eugene in like 1998 to go to OSU. then moved to Bend..so I didn't go far. Most of the rest of the family is long gone from eugene ( and oregon )
     

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