Is there a split face feature that would extend all the connected faces?

florian_ford

Hello, I feel so stupid right now. I am coming from DesignSparkMechanical and I wish OnShape would be as intuitive with regards to direct editing. 
Anyway I am trying to split a face by a line but I want the split to extend around the object, encompassing all connected faces.

How is this done in OS considering that the lateral faces of the object are extrudes so don't seem to have an editable sketch by default.

Thanks.

Narayan_K

@ florian_ford ,You can split the part but not the just face.

andrew_troup

I suggest you create a suitable plane or surface, and use "Split Part"

That will split all the faces of a part at its intersection with the chosen plane or surface.

However as @Narayan_K points out, this will not only split the faces; it will also split the part into two. I don't know of any way currently to do the former without also doing the latter.
(You can make a copy-in-place of the part if you want an unsplit part, but you cannot currently, AFAIK, have the split faces on that same part)

billy2

didn't they just add this capability? Maybe I'm missing the point here.

andrew_troup

@billy
The (most welcome) recent addition allows us to split surfaces, but the OP (it seems) was looking to split faces.
Do you know of a way to split faces without splitting the underlying solid body?

brucebartlett

No way to split faces yet but I believe it is built into the command to be added in the future.

billy2

These are OS surfaces, they just changed the split function to work on surfaces. I've been bugging them for trimmed surfaces and they gave us a split capability.




Do you guys know the difference between a surface and a face? I don't know. I've always thought there's a surface and then when it becomes trimmed it becomes a face. Not sure this is universally accepted or if I'm right. 

I just checked wikipedia and they don't define face vs. surface. 

andrew_troup

I have adopted the convention (from other MCAD) of using "face" in relation to solids and "surface" in relation to surface bodies.

brucebartlett

andrew_troup said:

I have adopted the convention (from other MCAD) of using "face" in relation to solids and "surface" in relation to surface bodies.

That's my understanding.

Therefore a split face is a continuous surface on the outside of a solid part which has a slit line across it. This split line can be used for modeling new features from "the classic being a draft for tooling" or for analytical purposes. 

billy2

looked it up, from the parasolid manual:



Doesn't say anything about a manifold, but that's parasolids. I think face is a loosely used term in our industry.
 

florian_ford I think your asking if you can split a body which would split all faces of that body? Yes you can.

Here I split a body with a surface:


In my case I extrude a line creating a surface (not a face), and then cut with the surface.

florian_ford

I don't yet fully (or even partially for that matter) grasp the concepts of solid geometry in Onshape but my idea was to split an extrude or a loft, shapes that are quite complex. An extrude of a complex sketch would have many connected faces that I would like to split at the same height without creating sketches from each flat face and splitting each face at the same level. I don't want to cut the internal geometry just the external faces because I want to increase the section of the outer wall or pull some faces to a greater thickness and so on.

But then again I come from a direct-editing background where almost everything is possible right from the 3D viewport and I might not have a good understanding of the design intent and specific ways a professional solution like Onshape works.

If I think better about it, it might be possible to just go into a sketch at the correct height, copy the existing shape, making it larger and extruding again.

I hope I am better understood now. 

andrew_troup

Thanks, @florian_ford

That was what your previous explanations led me to imagine you wanted (I thought they were actually pretty clear) 
Furthermore, that's a very reasonable thing to want to be able to do, and other MCAD modellers make it fairly straightforward. 
(Although Solidworks, in particular, could do with some improvement in this area, for instance, a fresh sketch is required for each split line, if you want to subdivide faces into several portions)

It is a safe bet that Onshape will offer this functionality shortly, and I hope it will be dead easy and yet powerful in the best traditions of the application.

For the moment, I'm guessing the best way to achieve what you want would be to split the entire part, thicken the faces you want to thicken, then "Boolean" the resulting sub-parts back into a single entity.

If you get stuck at any stage feel free to post a URL for your part here  (or a similar one, if it's sensitive). You will need to share with "Public".