This is a topic that some may initially find a little esoteric, maybe even dull to some. But I assure you, it has big implications. If your favorite history-based software had this sort of functionality, you might feel better about history.
In history-based modeling, you usually think of sketches as being history-based too. Not inside the sketch, but each group of entities grouped as a “sketch” has a certain order, and can even have parent-child relations with other sketches. In some of my posts on the Dezignstuff blog about how to improve history-based modeling, I suggested that a single sketch environment that wasn’t split up into separate “sketches” would make more sense and be easier to edit than the current deal where you get “out” of one sketch and “in” to another. This slows things down so much.
Plus, here is something that just drives me batty. Within a sketch, order doesn’t have much to do with anything. But between sketches, order has everything to do with it. So you’ve got this weird thing going on where sometimes you have to think history-based parent/child thoughts, and sometimes you don’t have to worry about that. It’s the same thing between parts and assemblies. Within a part, all your features are history-based, but in an assembly, you don’t worry about history. In fact, thinking history can get you in trouble. Except sometimes when you have history-based features within the assembly. So In SolidWorks, you’ve got this confusing layer cake of History, and Not History:
- within sketches: No
- between sketches: Yes
- features: Yes
- between parts: No
- mates: No
- incontext: No
- assembly features: Yes
- mates to assembly features: Yes
How do you keep all of that straight? Really? The thing is you don’t. Or most people don’t. They might add fillets or draft to a part, and it completely blows up in-context features or mates in the assembly. If assemblies were history-based, you’d never be able to make changes that made sense. Ay.
“Synchronous sketches” in Solid Edge just mean that the Yes after “between sketches” above at #2 becomes a No. “Synchronous sketches” in Solid Edge means that all the sketches exist together all at once. Not one before the other. So when you edit one sketch, half of them don’t disappear. One of the problems with history modeling is that is is so one-directional. You can only go forward with it. Making your sketches synchronous means that you can make relations to any sketch from any sketch, regardless of order.
In addition to Synchronous sketches allowing bi-directional interaction, Solid Edge also has what is known as the Blue Dot. The Blue Dot is an entity that transcends time and history. If you have a mesh of history-based sketches, you can use a Blue Dot to allow those sketches to react in a non-history based manner. This Blue Dot thing is cool. Especially if you do any surfacing in Solid Edge. I’m getting an example together to demo this a little.