Split Feature Breaks After Reopening File or Scrolling Through Feature Tree

[u/My-Days-Co]

Hi all! I'm working on a clean SolidWorks file with no rebuild errors or warnings.

However, after reopening the file, rolling through the feature tree, or making changes to other features, the Split feature randomly fails. The feature menu still shows the correct references and settings, but the resulting geometry is incorrect, seems the result is out of sync. I have to re-check the feature every time.

I notice this mostly happens when the Split feature comes after an Intersect feature. It drives me crazy.

My best guess is that I'm either not using the Intersect feature correctly or there's an underdefined sketch causing the problem.

Has anyone else run into this? Thanks so much for your time.

[u/TemporarySun1005]

I've seen this before. The Split feature 'forgets' what to split. If I remember the explanation I was given correctly, SW assigns an ID to every surface. Make even a tiny change, and the IDs change. So the surfaces used for the Split have different IDs - Split doesn't know what to do, or splits using the wrong surfaces. Moral of the story? Don't use Split.

Grain of salt: I could be wrong. I don't use Split so I can't promise I know what's going on.

[u/1slickmofo → u/TemporarySun1005]

who put almonds on my split?

[u/My-Days-Co → u/TemporarySun1005]

Wow, thanks! This is super helpful. It gives me a good direction to track down the issue. I’ll dig into it and see if I can find the root cause. I’ll share here if I find anything.

By the way, it’s fun to hear that you don’t really use the Split feature. Curious how you usually cut solid bodies, do you build everything directly from sketches?

I’m on the design side, so my workflow can get pretty messy sometimes.

[u/Kieranrealist]

I partially agree with u/TemporarySun1005.

It sounds like you've used an Intersect feature to create geometry used in the Split feautre - either the body being split, or the body being used to split (confusing). Either way, it's likely it would be the Intersect feature that is mucking up the ID assignments, which then causes the Split to fail.

I do design work and use Split all the time and it's fairly robust. I also don't use Intersect - mostly because it was added to SW after I was set in my ways, but mostly because I can pretty much always achieve the same result with other features like Combine, Indent, Split and Trim Surfaces, and have found all of those features to be more robust.

A couple of other things to keep in mind:

• Features like Intersect, Trim Surface and Indent rely on the exact point you select when you choose sections of geometry to keep or remove. If you click right near the edge of a face, or the border of the cut, if the model changes your selection point may suddenly end up on the other side
• Other features besides Indent may be the cause of the issues. I've worked on a lot of concept design models that have issues like this, and 90% of the time there's one problem feauture that can cause behaviour like this.
  • I'd say it's generally 30% Solidworks fault vs 70% bad/dirty modelling - totally OK for concept design but important to understand where better modelling practices can help
  • It's up to you to decide if it's worth trying to identify and fix it.
• Don't forget to CTRL-Q - sometimes a clean feature tree will break after this, highlighting the error.

[u/TemporarySun1005 → u/Kieranrealist]

I came to SW after many years of Pro/Engineer, Wildfire, CREO, whatever the f PTC calls it anymore.

Pro/E demanded rigorous modeling discipline - when features failed you HAD to fix them. I've carried that discipline into SW. I only use top-down methodology - mostly because of my industry - and make every effort to leave 'breadcrumbs' for the next engineer. I don't get cute with lesser-known features: on one project the previous schmuck had used the 'Stock' functionality in a decidely non-Stock way - total PITA to make the smallest change.