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how does splitting work with the timeline?
henry_feldman
Member Posts: 126 EDU
A little unclear if splitting is supposed to respect time. SO in the example below, I initially cut the big blue part with the plane you see with the purple arrow. Initially those side tabs with the green arrows were added after the split, and were extruded inside the split. The client then asked those tabs to farther out, and so I edited the extrude (which is way below the split) and changed the length to what you see below. It made each tab a separate part (which I could successfully boolean back together). Now that all seems inconsistent, if the split doesn't respect the timeline, then the boolean should fail, and if it does respect the timeline then it should not have made separate parts. Unless I totally misunderstand the concept. Any ideas?
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philip_thomas
Member, Moderator, Onshape Employees, Developers Posts: 1,381 
Again - none of us here can see the document so this is all supposition on our part.
That said, I will offer an observation about Onshape that is interesting, but may or may not explain this.
Booleans in Onshape are slightly different than in other cad systems. In those other systems, if a Boolean operation does not produce exactly one body as the outcome, then it fails. If a Boolean, say AnB produces nothing (a null set) - Onshape doesn't care because this is perfectly valid. If AnB produces 10 new bodies, that is also perfectly valid and Onshape doesn't care. If AuB produces no new bodies (and you select keep tools), then you will have exactly the same number of bodies after the operation as you did before. If you were expecting the same result you would get from another cad system (either an error or zero bodies), then you might say in Onshape, 'I have more parts than I was expecting'.
May or may may not apply here, but interesting
Philip.Philip Thomas - Onshape5
Answers
Onshape, Inc.
it is now shared with support. The specific split plane is the Right Split Plane, and boolean1 is where I had to repair that edit as above
Onshape, Inc.
I don't think you have to split these tabs, move them, and reconnect them.
By timeline, I think you're talking about the sequence of operations in the feature manager? I would refer to this as the order of the features as opposed to the timeline.
With a parametric modeler, to extend your tabs, you should edit the sketch that made the tabs in the 1st place. In that sketch there should be a dimension that specifies the tab length. If there isn't then your design intent is off and you have to change it to allow this change.
Once Tim gets access, I'm interested in the answer. I'm not clear about the question.
Timeline, sorry, don't mean to be rude. I used to teach this stuff and I felt naming/terminology was important, at least I use to think so.
The feature tree has order and history but it doesn't have time. How can it have history without a timeline? I don't know I'm probably going to lose this discussion.
Do you teach kids how to use CAD?
That said, I will offer an observation about Onshape that is interesting, but may or may not explain this.
Booleans in Onshape are slightly different than in other cad systems. In those other systems, if a Boolean operation does not produce exactly one body as the outcome, then it fails. If a Boolean, say AnB produces nothing (a null set) - Onshape doesn't care because this is perfectly valid. If AnB produces 10 new bodies, that is also perfectly valid and Onshape doesn't care. If AuB produces no new bodies (and you select keep tools), then you will have exactly the same number of bodies after the operation as you did before. If you were expecting the same result you would get from another cad system (either an error or zero bodies), then you might say in Onshape, 'I have more parts than I was expecting'.
May or may may not apply here, but interesting
Philip.
Split with plane produces 17 bodies, seems right (works):
Split with surface (sketch has a line in it):
Surface is analytic due to line entity in sketch. Analytic faces behave as planes. (FYI split with surface is different in SW):
Switch line to spline in sketch:
The surface is still an analytic face even using a spline as it's constructor. In geometry there are no lines everything's a curve, in this case a straight curve:
Ok so make the spline nonlinear:
Ok, this is what I wanted in the 1st place. Split with parametric surface (works):
Now make the spline linear again:
And were back to an analytic face (works?):
I don't think this is the problem, but it's interesting. When splitting with a surface, I'd like the split to be bound by the displayed surface, not analytical representations.
This isn't the issue here, I'm interested to see how this pans out,