Does SolidWorks do Direct Editing?

Does SolidWorks do direct editing? If you ask their marketing department, they do, but I think people who use the software might define things a little differently. To me, “direct edit” means that you directly manipulate the geometry without the abstraction of features that hold metadata. That’s part of it. But the most important thing about the idea of direct edit is that it is generally what people mean when they want to talk about a way of modeling that is “not history-based”. A more recently coined term to describe this would be “history-free”.
When you see an advertisement that says or implies SolidWorks does direct editing, what they are doing is just trying to minimize the advantage that some other modelers in the market right now hold over them, and it’s a big advantage, although few users seem to appreciate just how big of an advantage it actually is.

SolidWorks doesn’t really do direct edit. They do something that because of the interface (Instant3D, Move Face) looks a lot like direct edit, but it isn’t direct edit. And even if it were direct edit, it would only be a tiny fraction of the functionality of a real direct editor.

I’m not one to just make a claim and let it sit. Let me show you why I say SolidWorks does not do direct edit. When SolidWorks talks about direct edit, it is the Move Face feature or the Instant3D gimmick that they are referring to. Every time you use Move Face, it adds a feature to the tree, and thus, it adds another step in the rebuild sequence. The Move Face is a history-based feature that takes time to rebuild, and can be reordered, is subject to parent/child rules, can be rolled back, suppressed, frozen, and so forth. So it is a 100% citizen of the History-based scheme, even though it can operate on imported bodies, it creates history-based features on those bodies. Real direct edit does not leave a trail of edit instructions, it just edits the body.

Oh, and by the way, to get that Move Face to work, shown above, I had to remove or roll back all the fillet features. This is a limitation a real direct editor doesn’t have.

When you use Instant3D, you are just editing a history-based feature or its parent sketch in the background. This is a cool way to edit things that helps mitigate the downside of history-based features, but it isn’t direct edit.

In my book (that’s a metaphorical book, not a literal book), just putting an arrow on a face and moving it isn’t enough to make it direct edit. Adding or editing history-based features, and thus rebuild time, is exactly what people who move to direct edit tools are trying to get away from. Is there any purpose to carrying around the baggage of all of those edits? Especially on top of a static imported model, keeping a history of changes to rebuild is pointless.

Anyway, I assume that if you’re reading this article, you’re at least somewhat interested in direct edit. To me, direct edit is a portion of what Siemens built into Synchronous Technology. What is traditionally known as direct edit isn’t as powerful as it could be, so ST was developed to augment the usefulness of direct edit in a scheme that actually co-exists with history-based modeling. Both NX and Solid Edge make use of Synchronous Technology, but I’m most familiar with the Solid Edge implementation. I know what you’re thinking. I’m not obliged to say anything nice about Solid Edge. I’m just saying this because I spent the last four years of my life trying to broaden my horizons a little, and the technology I found in ST really does a great job of augmenting the kinds of things we can do with our CAD modelers.

In case the small-minded start feeling threatened, ST doesn’t replace history-based modeling, it augments it. Let me say that again. ST augments history-based modeling. Yes, in SE you can build a model that is 100% ST, or 100% history, or any combination of the two. That’s part of the beauty. So if you have Solid Edge and it turns out that you don’t like ST, or it doesn’t work for what you are doing, you don’t have to use it.

I actually wrote a book about ST for Solid Edge (10 chapters, about 150 pages in PDF format with downloads) to try to communicate to history-based users just what ST does. It’s available for download along with sample movies and parts. You can get a free copy of SE to run for a while if you’d like to play along as you read (as long as you don’t consider your your contact info to be worth anything). The first couple of chapters cover the concept, and the rest covers details of how you make it work. One of the things the book is meant to do is to convince history-based users that there is a problem. How many times do you find yourself cursing when you make a change and features fail? Or you can’t reorder features? Or parts take forever to rebuild? Or when you have to rethink your design intent? It’s a mess and a tangle to find relationships and then recreate them, or maybe you have to rebuild sketches, or maybe even delete and recreate stuff just because you changed your mind about how it should all react to changes. Frustrating. Waste of time.

But on the other hand, there are some types of features that you really need to drive with sketches. Some things really matter about the order, or at least it makes things easier to think of the operations as having some sort of order. So the Synchronous model comes first, and you build your history-based features on top of that. You can go back and make Synchronous changes to the body, and the history-based model will update. Things you want to use history for will be text-driven extrusions, fillets, shell features sometimes.

While I’m at the task of mythbusting, let’s just get this thing about parametrics out of the way. Synchronous models are parametric. I’ve seen smart people who should know better make this mistake. Parametric is not a synonym for history-based. A Synchronous model can be driven completely parametrically – using dimensions, and relations, and equations and tables. The main things that ST avoids are parent/child relations, and a stack of ordered features that need to be rebuilt and often fail.

Here’s a simple demo that shows generally what it does. This is a few years old, but it shows the power ST has over design intent.

I have to say I really don’t understand why ST is not a bigger deal. I mean you can do all of your history-based stuff PLUS all of the direct edit stuff. Sure, ‘Works tends more toward flashy, and Edge is more utilitarian, but I believe there is a better plan behind development of Edge than ‘Works, and fewer crashes with Edge if I have to be honest.

And NO, ‘Works doesn’t have anything that even comes close to Synchronous Technology.

7 Replies to “Does SolidWorks do Direct Editing?”

  1. Matt-
    Thanks for the write up. The video does a good job of explaining the abilities of Live Rules and parameters. I feel it would be really powerful to show a simple example of making changes to an assembly! Making changes to multiple parts at one time. Maybe the next video?

  2. When Synchronous Technology finally clicked for me, I longed for something that powerful in SolidWorks.

    I tried Instant3D, and agree that it is mostly a gimmick. It is not a good tool for direct editing because it comes with the liability of indirect edits. If any child features reference that face you’re moving, they can move with it.

    The Move Face feature in SolidWorks is a good way to modify certain faces in a part, but I’ve found it can have a critical impact on the rebuild time if you rely on it too much. And sometimes Move Face becomes useless if there’s a fillet or chamfer in the way.

  3. Great Article. It’s nice to get a different perspective. If you had to work on a design project, which CAD package would you prefer? Solidworks or Solid Edge? Why and why not?

    1. It depends. If it were a machine design project, with mostly prismatic parts, 100% Solid Edge. That type of part is exactly what Synch Tech is made for. It also happens to be what most CAD models are built from. SE is more stable and less likely to change in ways that make your work less valuable.

      If It were a complex shape job, probably either could do it, but both would require some hair pulling. SolidWorks would get a slight edge due to a couple of features, if you’ll forgive the pun. I’d probably choose NX, truthfully. A lot of real surfacing work is simply beyond what you can expect from the mid-range.

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