design revision on sw model

case: a quite complex surfacing cad model need to be revised due to technical/manufacturing problem
problem: SW is a history driven, changing things over here can screw up shape over there.

question: how do you guys deal with it? mostly what i do is just delete the suface and build again on top of it, but isn’t this defeating the purpose of SW?

Unfortunately, if you choose to amend the original feature and its driving hundreds of features downstream then it will cause the model to fall over and then hours spent trying to fix it. If you want to maintain a clean CAD model then there isn’t much alternative.

The alternative is to delete and rebuild the surface further down the feature tree. But building over the top of existing features is not ideal because you can end up with an inefficient, unstable CAD model.

The trick with CAD modelling is trying to build your model with contingency for the event of needing to change things. It comes down to design intent, and making sure you use appropriate references when you build each feature. For example, a converted silhouette edge can often be a very unstable sketch feature to reference when geometry changes.

I’ll second chris’s point. You have to learn where and when to create relationships and references when you’re building sketches, surfaces, features, etc. so that your model will update with few or no hiccups. It is something I still struggle with and just takes practice.

If it’s just a small change, deleting and rebuilding a surface or solid at the end of the process tree isn’t a terrible way to go. I’ve had projects that changed dramatically 3/4 of the way through a build, but I left the old process tree in tact as reference and as a sort of roadmap to remember how I got to the final solution, should I need to make any small changes in the future.

If you have to keep repeating this action, however, it can create an incredibly convoluted and unstable part that will repeated fail rebuilds or edits.

It’s definitely one of the love/hates of solidworks.

The ability to go back and change a sketch and therefore a feature is great, but it can screw you up.

Especially on complex organic shapes. Sometimes you can just go back and change some relations but often you need to do major surgery. I find that centrelines, using planes and referencing from the origin/right/front/top planes always helps a bit.

As every one points out; you need robust mates/references/relations when dealing with complex surfaces. Its much more easier to repair a model with “hard coded” references then one with references floating on a surface or edge. Often you really need that relation to be positioned at the exact middle of i.e a surface. There are no bullet proof way to do it, you just have to learn the hard way how features behave when altered too much and how different mates/references/relations follow.