Announcement

Collapse
No announcement yet.

Parametric vs Direct Modeling

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • Parametric vs Direct Modeling

    I finally got some official SolidWorks training last week... a full 40 hours, and I have to say that I am extremely impressed. It has made me question everything I believed in. I'm loving parametric modeling!

    I've always been a strong believer in SpaceClaim, DezignSpark Mechanical, and other direct modelers because that is what I started with, but here are my current thoughts:

    - Parametric is ideal for complex projects that have a pretty good design intent from the beginning, but will also require precise changes. The parametric nature makes it easy to keep your dimensions straight. The downside would be the higher learning curve. I believe official training on best practices is needed in order to fully utilize the software and create "sound" models.

    - Direct Modeling is excellent for more fluid designs and is very easy to learn. Models aren't constrained by parameters and can be shifted as needed just by pushing and pulling on features. There is no history tree to keep up with, but this is can be a down side as well. Complex models can be created, but making sure all your dimensions stay where they need to be when you make changes to the geometry can be difficult on complex models.

    - Features from both have been merging a little bit. SolidWorks has their "instant 3D" that lets you drag faces on the fly. SpaceClaim now has a locking mechanism that lets you lock in critical dimensions so they don't change when pulling geometry around.

    Thoughts?

  • #2
    For me, there has been always "simple" : direct modeling is more suitable for "organic" modeling. Works like modelling a creature, organic forms. And parametric modelling is aimed and HAS TO BE (in my opinion) used for everything else: from a simple fan shroud to a complex assembly of moving parts. I used to model in 3Dmax. In the moment I started in the 3d printing world I realiced that despite 3dmax being extremly powerfull it was not suitable for designing something simple but that required specific measures, proportions, relations. Another situation where you really notice the difference: when you design something and then print it... suddenly you realice that the size is not correct, an angle is not correct... makeing such modification are way much easier in solidworks (or any other parametric CAD).

    Comment


    • #3
      You might want to try tinkering around with Fusion360. It has a pretty strong marriage of parametric modeling and direct modeling capabilities. I'm from the parametric world, so I don't know if it's a common feature in direct modeling, but I've read a lot of people rave about the "T-spline" functionality in Fusion 360 for direct modeling. There's a guy who's done some phenomenal examples of direct modeling capabilities on their discussion forum. I personally like parametric design because of the control and flexibility you can exert on a model. Also, my artistic ability is pretty low, so direct modeling leaves me frustrated sometimes.

      Comment


      • #4
        I taught Autodesk Inventor for a number of years. It's too bad its so expensive as it a really good parametric modeling software. I urge you to try it if you can. Its free to students and teachers at all levels. Currently I am using Sketchup and Cadd. I have used 123d and tried Fusion 360, but found them lacking.

        I am a retired engineer so when I got into true modeling, it took me some time to adjust. I am not an artistic type to begin with.

        Comment


        • #5
          Originally posted by cwaa View Post
          I taught Autodesk Inventor for a number of years. It's too bad its so expensive as it a really good parametric modeling software. I urge you to try it if you can. Its free to students and teachers at all levels. Currently I am using Sketchup and Cadd. I have used 123d and tried Fusion 360, but found them lacking.

          I am a retired engineer so when I got into true modeling, it took me some time to adjust. I am not an artistic type to begin with.
          What did you find lacking in Fusion 360? I am very impressed with the features that it has, especially for the price. I'm also under the impression that many of the features of Inventor are making their way into Fusion 360, but I could be wrong. My biggest complaint is that the user interface doesn't feel as smooth as Solidworks. However, it's still a comparatively new software package and it's been a while since I've used it for a few hours, so some of the UI bugs may have been worked out.

          Onshape is another powerful parametric drafting system that is free to try. It has a very close look and feel to Solidworks. The catch with that one is that it requires a constant internet connection. It's completely cloud based, so there's nothing to install, but sometimes there can be input lag that is off-putting to some people.

          I don't have any relationship with either of the companies I'm plugging, I just like 3d modeling and drafting a little too much. I always am interested in hearing from people with more experience than I do though, that's why I was wondering what you found lacking in Fusion 360. I'm fortunate to have had a great technology program in my high school, nearly 20 years ago. The classes started out doing 2d drawing and detailing in AutoCAD, then moved to 3d modeling in AutoCAD, and then finally into parametric modeling in Solidworks (also a little bit of modeling and animation in Lightwave). Driving dimensions, equations, and geometric relations made me never look back at direct modeling. Organic curves and complex geometry may be more difficult in parametric systems, but I rarely run into them in what I make. Plus, they just highlight how bad of an artist I am, so that makes it even easier to avoid their use.

          Comment


          • #6
            I guess the reason I was not impressed with Fusion 360 because it wasn't Inventor. Maybe I should try it again. I have been Using Sketchup, but I have gotten into some very detailed modeling and Sketchup can't create a model without many errors. I have tried to use netfabb and make printable.com, but the model still doesn't print right. After a little research I find out Sketchup can't print true circles, and its smallest increment of length is 1/16 of an inch.
            One person said to blow up your work by a scale of 1000 and then when ready to print, scale it back down and most detail and accuracy will remain. Doesn't sound like what I want to do.

            Comment


            • #7
              Aha, good to hear you see some positives in parametric. I couldn't imagine producing any assemblies that weren't parametric, sounds frustrating.
              I agree that learning parametric is best done through workshops/classes with a curriculum, failing that an experienced person should be able to provide tutoring to a novice. Workflow, top down and bottom up techniques etc. Unfortunately the software in the industry whilst powerful is riddled with bugs and nuances. SolidWorks is no exception (if not one of the worst offenders).

              IMO Fusion 360 and Onshape are both good tools that are still in their infancy. I can say that their drawing generation is severely lacking when compared to traditional CAD offerings like SolidWorks, as are a few other features that traditional CAD does really well (design tables, part and assembly families etc.). That said cloud CAD is likely the future as some of the ideas they are incorporating have the potential to greatly improve CAD work flows. Concurrent multi-user CAD modelling is huge for engineering. To summarise I would definitely say they are worth picking up as they can do most of what traditional CAD can do (and a few things traditional CAD cannot).
              Also worth noting that at SolidWorks worlds 2015 they brought up Cloud based SW, so its probably only a matter of time before SW moves their focus to cloud services.

              Comment

              Related Links

              Collapse
              Working...
              X