Correct order for slicing a component with a rectangle?

I’m sorry to have to ask this but I cannot seem to slice this tall component with a rectangle correctly. I want to slice it in the middle so I have two sections of the tall component capped off.

I tried selecting with model but I cannot get two parts of the component even after moving a copy and deleting.

what order do I have wrong?

thanks for any insight.

Try this:

  • cut (erase) the rectangle
  • open the prism for edit
  • do Edit->Paste in Place
  • select all the contents of the prism+rectangle
  • do Intersect Faces with->selection
  • clean up the remains of the cutting rectangle
  • if necessary, trace an edge on the end of each prism piece to create a face
  • check for reversed faces and correct as necessary

The trick with Intersect Faces is that the new Edges are created in whatever context is open at the time, so to cut the prism you need to first open it for edit.

Edit the ‘box’ if it’s a container.
Select all of the ‘box’ geometry [edges and faces], then Edit > Cut.
Edit the ‘tall’ component.
Edit > Paste-In-Place
This inserts the ‘box’ geometry into the tall component [selected].
If you need to, use treble-click or a ‘fence’ to select all of the box’s geometry.
Use Context-menu > Reverse Faces [this is needed later…]
Use Context-menu > Intersect > with Context.
The ‘box’ now cuts the ‘tall’ geometry.
Erase the unwanted outer parts of the ‘box’.
Also erase the unwanted face in the cut mid-portion of the tall part.
You should now have the tall part cut into two pieces, each with a properly oriented face on the newly cut parts.

Note how reversing the box’s faces when I said to, set them up to be suitably oriented in the next step when you tidy up.
You don’t have to do it then, but if you don’t you have to select the incorrectly oriented faces and reverse them later anyway…

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Here’s a visual of what has been explained above.


Thank you guys. When I tried before, I think it was because I didn’t know how to open the component (tall object), and select the rectangle to intersect too. So whatever I was doing was not really editing the component.

But with your specific steps, that should solve my problem. Thank you for all of your time again. I will try this now.

There is a subtly in there that’s worth knowing. When you click-drag select something, going from right to left, anything that is within the selection gets selected. If you drag from left to right, only things that are entirely enclosed get selected. So, the drag through the middle of that front face, because it was right to left, also selected the new geometry inside the prism model.

Ahhhh, that is good to know! I didn’t think of that before but did see it in videos. I try to watch a lot of videos on sketchup but there are so many little things like that which are easy to miss.

Thank you again.

Yep, worked perfectly guys. The part I could not think of on my own was the cut and paste in place. That is the part I didn’t think of for trying to be able to edit and select what was needed.

Really appreciate it,


One part I was puzzled by was the reverse faces. That then saves you having to reverse faces after the intersecting. You could not-reverse-face at first, and then reverse face the two faces inside the prism.