How can I "cut" a diagonal across a model of 4X8 siding


I downloaded a model of standard 4X8 foot siding. I would like to “cut” a diagonal across it as at a jobsite. However, I can’t get the push/pull tool to work as there are several faces in the vertical slots. Is there a way to make the diagonal cut some other way?




I think the question was how to cut a diagonal on the face, say corner to corner, but the push pull won’t work because of the extra edges and faces associated with the grooves in the siding.


Just rotate the cutting plane so it goes corner to corner and follow the rest of Jeff’s instructions.


probably so… same problem with the grooves either way.


It seems to me that the elephant in the room is the question of whether or not it’s really necessary to model the grooves in the siding. That adds a lot of arguably unnecessary geometry to the model, and unless it is your explicit purpose to show a detail of a sheet of siding rather than simply a house covered in the stuff, you should probably use a texture to depict the siding. Not only would it save your model from whole lot of excess weight, the texture would probably look better anyway: closely spaced edges, such as on grooves, tend to bleed together when you zoom out.



Thank you all for your responses. I do just want to cut a corner off the 4X8 sheet. The cut is just a line from one side to a point on the top, not at the corner. I chose to download a model of the siding, not realizing the complexity involved. I could just use texture for this project. However, I also wanted to learn a technique to make such a cut. I have a similar problem with a roofing shingle model I downloaded. When I get to the edge of the roof, the shingle hands over and I would like to just cut it off. The use of a plane should work for this situation also.

Unfortunately, I haven’t been in a position to try your suggestions, but I can’t wait to try. Do I intersect the plane with the model while the model is in edit or can I just point to it and make the intersection?

Again, I really appreciate your time and expertise.


How you intersect depends on the context and what you want to achieve. you can intersect with Selection, with Model or with Context. They will give different results for different reasons. Basically If the roof shingle or siding etc is a group or component, then you need to intersect while in the group and intersect with Model, so that it is intersecting with something outside the group, ie; the cutting plane.
Here is a sphere being cut with this method, that I made for something else. You can see here I deliberately changed the angle of the cut so that it didn’t line up with the hidden geometry.

If the cutting lane is already in the same context, as in inside the group, then you can select the relevant faces and intersect Selection, this will give you the cut face in place also, but can be harder to remove the excess.
You can intersect two closed groups and it will give you the geometry of the intersecting edges outside both groups. You can then select and copy that geometry, open a group and paste in place and you have the cut that way.
So there are many ways to slice a cat, as they almost say.


I am obviously doing something wrong. I think I follow your great example, but when I delete the plane and then try to highlight the section to delete, the whole siding sheet is deleted. In other words, there is o intersection. I downloaded the model, made it a group, placed a plane where I wanted to make the cut, selected the intersection with the model, deleted the plane. I try to delete the piece that is not wanted, and the whole 4X8 sheet disappears. The only thing left is the line I drew marking the cut line. Where did I go wrong?


If you post your model, the helpful folks here can probably tell you exactly where you went wrong. But it is hard based only on words, which unfortunately always contain unstated assumptions or actions.


Did you make the plane a group? Did you select the plane and activate the intersection command “with model” as well?


In it’s most basic form you don’t need to make it be a group, that was was specif to one problem and might be more than necessary for you.
If the object you want to cut is raw geometry simply place the cutting plane though it, select all of it, right click and Intersect with Selection.

It’s possible that you have downloaded a Group and made it a group again, causing it to become a nested group …
So as mentioned above the model would help, at the very least a screen shot.

Making a "cut" to an existing model

Thanks again. I will try to send the model as an attachment .skp file. I got it from 3D Warehouse by doing a search for “siding”. It is titled “T111 Siding” by Shedman. It is in the 2nd column, 3rd row. I think I messed up by not making the plane a group. Your examples are great, especially this one. Now, I don’t see any paperclip icon to attach the file.


There is a little upload Icon just above where you are typing your reply. The 7th icon across sort of a bar with an arrow pointing up. That’s the attachment.

If you mean this then it isn’t a group and you don’t need to make a group.
Just make a rectangle and put it where you want to cut, intersect and delete.


If you have got it from 3dWH it’s probably still a component instance in your model.
I also anticipate that you want to keep an uncut rectangular version too ?
If so insert an instance for the one you want to cut…
Select it - context-menu > make_unique.
Definition “xxxx” is joined by “xxxx#1” - a unique duplicate.
It is initially identical with its sibling…
If desired you could rename that definition “xxxx-cut” ?

Now you edit that component-instance and work inside it.

As @Box has clearly show in the last post, you now need to draw the rectangle, select and intersect, then erase the unwanted parts…
Exit the edit and now you should have a version of that component with its corner cut off…


I almost got it to work by exploding the siding group and passing a plane (made into a group) along the cut line. The first section I deleted worked fine, but the remainders seemed to require deleting each segment. I suspect it is in how I am manipulating the selection tool. Here is the file I am using.siding.skb (151.1 KB)


The SKB file is the backup file.
The SKP is the right one - although simply renaming SKB to SKP makes it usable…


That is indeed a component instance - as I surmised…
No need to ‘explode’ anything…

Edit the instance and make the intersection as @Box explained…
To erase the unwanted parts by fence, make sure you drag in the correct direction - right>left…
Also adjust your view point so it’s easy to see/select…

Remember the ‘make_unique’ tip if you want to keep an uncut version…


It’s the same one I used in the gif above, but as I downloaded and opened the actual siding model I was already inside the component for editing. But mentioning that now is just going to confuse things.


Gentlemen, you have been more than diligent in your efforts to coach me through this process. Your examples were outstanding. Yes, I finally got one to work. I am a little uncertain as to exactly what made it work, but now that I have done it once, I expect to be able to duplicate the cut again. I will certainly save your examples so that I can review them several more times.

Thank you again.