When Design Intent Unravels: Part 1

I started out this blog post trying to recreate the magic Ilya Nazarenko showed as he demo’ed the basics of Synchronous Technology. The main thing I proved by that was that I’m not the same kind of wizard that Ilya is. I must be good at something else, because I’m certainly not good at the same things he’s good at. So the blog post has evolved into something else. I’ll get back to Ilya’s magic, but this is going to become a multi-part post.

What I want to show here is how unbelievably awkward it is to work with design intent on a history based system, and by comparison, how easy it is to work with Synchronous Technology. Now to do that, I’m going to have to show Ilya’s presentation, but all in good time.

First let’s start with a simple part. This is like the part Ilya used, but I’ve created it in SolidWorks here. Let’s make some changes. The order of features is:

1. base block
2. cut on left side
3. holes
4. big fillets
5. small fillets
6. cut on right side

Your design intent is limited to what you can do with the order of the features. For example, the holes can’t be concentric with the rounded corners, because the corners didn’t exist when the holes were made. To change that, you have to reorder the holes after the fillets or the fillets before the holes. But if you dimension the holes from an edge created by a fillet, you’re going to History-CAD Hell. That’s a big no-no with history-CAD. Don’t dimension to edges created by fillets. Anyone who has been around a while will tell you that.

If you want to add draft to the part, you’re going to have to figure out where in the tree that has to go to avoid offending the fillets, but also to avoid messing up the holes.

Maybe you want to make the two triangular cut outs the same. But suddenly it matters which one you use to be driving, and which is driven, because they are two separate features. But one is made again after the fillets, and isn’t dimensioned the same way.

So even on a simple part like this, you can get yourself into a real tangle if the part wasn’t created correctly. Sure, it can be done, but why does it need to be done? Why do you need to be a hero/expert to make changes to a part? What value does all of that information have?

Finally, let’s say that this part was made in VX, and we all know that VX has gone down the tubes. So you bailed out of VX and moved to HistoryWorks or whatever. And now you only have one feature in the history tree. IMPORTED. Hmmm. Suddenly you feel like you have no design intent whatsoever (because you don’t). You could use Move Face… (sorry, had to go there). What to do. Well, you could rebuild it in HistoryWorks, but then you’d just have the same problems the guy above has.

Or you could just bring it into Synchronous Technology. In Synchronous Technology, prismatic geometry like this is always native. Here’s the deal in ST:

1. You decide design intent when you need it, not before you need it, and you never have to rebuild or reorder a part to change design intent
2. Order of feature creation means nothing
3. You can still use geometrical constraints and dimensions to drive intelligence in your parts
4. Imported data in most cases has as much intelligence as native data
5. You can make changes in ST that you would not even dream of making with HistoryWorks

In Part 2, I’ll show the control you have in ST.