Difficulty with CAD Modeling

Discussion in 'Software' started by Mbalducci1990, Jan 22, 2016.

  1. Mbalducci1990
    Joined: Jan 2016
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    Mbalducci1990 Junior Member

    I am an engineering student that has been using Autodesk Inventor for the past year. I am good with the program, but I am struggling with creating smooth continuous surfaces.

    The project I am working on is a stand up jet ski and the top deck is giving me difficulty. I am trying to model it based off the Kawasaki SXR. I have tried lofting cross sections and I have tried creating a wireframe model and boundary patching. I also tried freeform modeling by starting with low poly and subdividing. None of these methods are working for what I am trying to do.

    I noticed that there is a poll on this forum that asks what programs everyone uses - and Inventor isn't even on that list. Is there a reason for this? I want to eventually learn Solidworks, but for right now I just need to get this project done with whatever tool is available to me.
     
  2. W9GFO
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    W9GFO Senior Member

    Autodesk Fusion 360 has T-Splines which work really well for sculpting organic shapes. It's free (for students and hobbyists), and should be compatible with Inventor.

     
  3. Mbalducci1990
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    Mbalducci1990 Junior Member

    I haven't tried Autodesk Fusion yet. I have heard of t-splines and I thought that inventor's freeform tool is the same as Fusion. I will check it out tonight.

    It has been my thought that Fusion is the next generation of Inventor.. That Inventor has it's limitations due to an older foundation of programming and bloated with features that accumulated over the years.
     
  4. W9GFO
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    W9GFO Senior Member

    I just starting using Fusion 360, it's relatively a new product, it's not perfect, but they are constantly adding features to it. The forum is active, questions are answered very quickly. Inventor certainly has more features but for what I do, Fusion 360 is amazing. If they keep improving it I'm not sure what reason there will be to use Inventor.

    It's cloud based like OnShape but has the very important feature (to me) that it can be used offline. If OnShape could be used offline I would be learning it instead but the online only thing is a deal breaker for me.
     
  5. SukiSolo
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    SukiSolo Senior Member

    Most surface modelling regardless of program is dependent on the curves. There are usually several different options of how to construct the desired geometry. Sometimes you have to abandon some of the original curves and use another method. It's partly down to learning how each programs' algorithms generate a certain type of form. Also although it is worth starting with tight model tolerances, try a little more freedom with the curves. It can be only a few tenths of a mm can make a huge difference. Make sure your (B)splines ie Degree 3 curves, have as few nodes as possible to generate the desired shape.

    In general the simpler you can create the base form the better as it allows for more complexity on the final few operations. Note that there are specific ways of holding things like draft taper when dealing with moderately complex shapes. T splines have been available in Rhino for years....;)
     
  6. Mbalducci1990
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    Mbalducci1990 Junior Member

    Great suggestion for the Fusion 360. It's been some time since I used Fusion and I am very impressed by it. I love being able to save time in assemblies by placing parts directly from McMaster, opposed to having to manually save and import. I keep finding and discovering things through their many tutorials on their youtube channel. I am actually making progress now and I realize there is alot to learn. I am on the right track though.

    My only concern is how Fusion 360 will shape itself in a professional setting. Right now it seems about 95% of jobs local to me are loyal to Solidworks and 5% are loyal to Inventor. I had a hard time trying to get into Solidworks, but Fusion I was able to fire it up and get right to work. So far with my limited experience, Fusion is just as capable as Solidworks (and they are constantly updating - another update set for today).

    I was thinking that I could get comfortable with Fusion and since the cost is very good, I could get a subscription and use it at where ever I may work (regardless of what software they use). The only problem with that may be feature recognition between the platforms.
     
  7. Squidly-Diddly
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    Squidly-Diddly Senior Member

    Solidworks isn't geared to T-Splines and other organic curves too much.

    More for when you are going to send the files to a shop to actually mill something.

    AutoDesk (Autocad, Revit, Inventor, Fusion) has FREE student lic online. Solidworks student edition costs $90/year IIRC.

    IIRC more places still use old Autocad than anything else and is considered best once you know what you are doing and are reusing or reworking a basic design. Circuit board designers to architects mostly use Autocad DRAFTING software.
     
  8. W9GFO
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    W9GFO Senior Member

    Not sure I can agree that most circuit board designers use AutoCad, none that I know of do.

    FYI, military veterans can get the student edition of Solidworks for $20.

    I used to mentor a FRC team, Solidworks provided us with about 40 licenses each year for no charge. All we had to do was ask.
     
  9. TANSL
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    TANSL Senior Member

    I agree totally with Squiddly-diddly. In the part of the world with which I have had professional relationships (mainly, but not only, Europe) many companies have specific software for the naval architecture calculations and use AutoCAD as DRAFTING software.
     
  10. Mbalducci1990
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    Mbalducci1990 Junior Member

    I didn't know that AutoCAD can be used for circuit board design. I guess it could since it can draw in layers. There are guides online to convert dxf/dwg to gerber format for manufacturing.

    I have the solidworks student edition that I was able to get 1-year for $80. It would be ideal that I were to learn Solidworks since that seems to be popular in my area (alongside AutoCAD). They do have alot of extensions that allow you to get costs of sheet metal designs and CAM. It seems that Autodesk is really pushing product development in Fusion and trying to catch up to Inventor and Solidworks. They already have some nice tools built in there.

    I don't currently have any intention in getting into naval architecture. I am studying mechanical engineering first and foremost. It allows me some flexibility in playing with different things before getting into any specific area of engineering.

    Anyways, I have been watching alot of webinars and tutorials in t-spline modeling for Rhino 3D. They are the same tools that are available in Inventor, Fusion 360, and the extension to solidworks, tsElements. I love that cross platform work flow. The problem is that the curvature that I am looking for is very difficult even for t-splines. It's just something that takes time and experience to achieve.
     
  11. TANSL
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    TANSL Senior Member

    Try to work with other types of curves and/or surfaces.
    Rhino, for its price, is one of the best programs for 3D modeling
     
  12. SukiSolo
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    SukiSolo Senior Member

    You can technically draw all 3D stuff in 2D, though some things are a right pain. There are equally lots of 3D things much easier (in some ways) in 2D like extrusions, circuit boards etc. You will also find that a lot of the 'tools' for sheet metal are not quite 'right' in the real world unless you have the specific bend radii (and any other distortion) that occurs on particular brands of sheet forming machine and the forms they use...;) been there...;) I own up to starting with 'DOGS' in the early/mid 80s, followed by Autocad and others after. Last set of tracing paper/film drawings was in '93.... I am frequently disappointed by the quality of CAD plotted drawings, partly software related but also operator laziness and often far too hard to read and not clear and artistic which they should be.

    If you describe something as having 'complex curvature' it may be you are not breaking the elements of the curvature down correctly. This makes it harder to model. Try sketching the item using relatively simple curves and forms to start with, this might help understand the base surfaces you need.

    You will also note that Rhino is a SW Gold partner. If you can't create the surface in SW, you can in Rhino, and import it, then work on it. It remains a parametric operation, you can change the surface import and regen the model in SW.

    Personally I quite like the idea of stuff like 'Onshape'. When you consider how much money and time is lost in CAD translation....;) but that's a little off topic.
     

  13. Mbalducci1990
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    Mbalducci1990 Junior Member

    I have used a PCB CAD before and I can't recall the name of it. The nice thing about it was the vast database accessible through third parties. Things like SMD footprints were easily accessible. AutoCAD electrical has similar features? I have always discredited AutoCAD because I felt like Inventor was just a superior program in every way. I guess it is shaping up to be a program to have in my toolbox. My only experience with AutoCAD is exporting sketches from Inventor and laying out templates in AutoCAD for laser cutting.




    I agree with having to break down the elements of the curvature. I am shooting from the hip too much. I have been sketching the side profile and kind of just winging the rest.




    CAD translation is the single most frustrating thing I have encountered since learning CAD programs. I like to think of it this way: a team of people are working on the same project with the same end result. They say:

    "We are working on a project that must be done by the end of the month and need to hire extra help. The problem is that their Stanley Hammers arent inter-operable with our Dewalt Hammers."

    Now replace Stanley Hammer with Autodesk and Dewalt Hammer with Solidworks. Sounds ridiculous?
     
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