Bisecting Solid Objects

I am a woodworker that is trying to use sketchup to make 3D models of the edge grain cutting boards I make. They are complex geometric patterns. I want to simulate the process in design that I use for building them in the shop.

First pieces are laminated together to form flat panels. The panels are then cut into narrow widths and turned on their ends to be laminated together again into a new panel of edge grain. They are then cut again cross wise and turned on their edges to form end grain panels. During this whole process the pieces are laminated together in different species and colour so that, when they are finally assembled in the end grain process they form patterns.

So I basically need to color objects different colors to reflect the different species which is not a problem. The problem comes in cutting the work into pieces. I have tried creating a flat plane to bisect the object but, although a line is created around the object in question, it stays together when I try to pull it apart. I have tried by making the object a group and then ungrouping it after the plane has been inserted or starting with the object ungrouped. Then one surface pulls away.

I am using Sketchup Free which may be the problem. Can anyone help with this?

First make sure that your cutting plane is inside the group/component so that your Intersect Faces operation actually divides the faces of the object. Then instead of trying to pull the geometry apart, select the bit you want to move away from the other bit and use Move/Copy. After you’ve made the copy, erase the unneeded geometry.

It’s not really the problem. You would find that you could save yourself a lot of work if you used the Solid Tools which are included in SketchUP Go. Not free but if your time has any value, well worth the subscription.

BTW, your forum profile says you are using SketchUp 2018 Pro. Do you still have that version? In any case, it’s time to update your forum profile.

Thank you. I wasn’t aware of that. I did have sketchup pro years ago when I was a student and it was affordable. Now it is out of the question but I will update my profile

Sorry, can you tell me where I update my forum profile?

Please see attached photo. The object has been bisected but, when I select the top half to move the entire object is selected

That rectangle is just lines… there is not a plane there to cut the box.

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I’m so sorry for my ignorance. I guess I don’t understand the difference between a plane and a rectangle that has been made into an object

I watched that video. And I followed the same process to bisect the object but the object remains a solid group when I try to move one part of the model away

Probably best off you share your actual model so we can see what you are doing.

Why do you need to bisect the cube shape? Can’t you just draw the top half the size you want, make is a group and then draw the bottom half?

Thanks Bmike but it is

because I am trying to make something that is made of many pieces that have been cut to uniform lengths and then reassembled in a pattern and then cut and reassembled to make a third pattern so that you end up with something like the picture

Something like that is impossible to reverse engineer and I could just get a pile of hardwood and start cutting to try and come up with the layers that, when shifted over and over and recut would result in this pattern but S4S (square 4 sides) kiln diried hardwood is extremely expensive. The wood in the picture would alone cost around $200

This is actually far simpler to lifeless than it is to build on the real world… remember, you don’t need to model stock pieces and cut them down to size… you can just model the piece you need in the end… draw a triangle and use push/pull to give it height. Select it all and make it a component. Repeat until you have one of each color of wood triangle… then move them into place using Move.


Thank you TheOnlyAaron. But I think you are talking about what most people use sketchup for. That is to replicate some kind of thing into a sketchup drawing. Your method would work fine to replicate that board in sketchup but what would it tell me about how it is made? Unless you think it is made of hundreds of tiny pieces that are glued together in a pattern? I can assure you, that is not the case. What I am trying to figure out is - How do you start with flat boards showing surface grain, cut them into strips, rotate them showing edge grain and laminate the sticks together (varying the species and colors) into a panel showing all edge grain, then cut that panel crosswise into strips (at an angle) and rotate the strips into edge grain in patterns. It is the construction I am trying to create, not the replication of an image. And to do that I need to know how to cut an object into pieces. I’ve linked a video on how they are made if anyone is interested3D cutting board

I understand how the cutting board is made. I am just trying to tell you how to do it with SketchUp. Unlike pieces of wood, there is no saw to chop through your stacked groups. Making something in SketchUp does not always work the way fabrication does.

What are you wanting to get out of sketchup?
Do you want to use it to demonstrate how they are made, show the various steps?
Or do you want to use it as a design tool and mix and match and chop to develop your own designs?

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The third option. As I was saying before. Buying hardwood to experiment on how to achieve an end pattern is a very expensive option full of trial and error. So I want to use sketchup to simulate the process in the shop but do it digitally. (Throwing digital pieces in the trash is a LOT cheaper) I want to start out with flat board shapes the same as what I would be buying, and cut them and assemble them and recut them and reassemble them to get the design I am looking for (like the picture but there are many, many variations) and, to do that, I need to know how to cut things into different pieces in sketchup. Then I will have a game plan to follow in the shop. But maybe I will try giving Sketchup Go a trial and use ‘Solid Tools’ that are not in sketchup free as Dave R pointed out.

What happened to the 2018 version you had?
What you want to do it quite possible, but it’s not really something to learn on. You should spend some time at the campus and get the fundamentals down. You need to understand about grouping and intersecting and outer shell etc
If you can get a good understanding of these things you should be able to work with the piece you describe.

It was a web based subscription that was based on my being a student at the time and very affordable.

Ok. So you are more familiar with the web version than the desktop version.
This is done using the desktop, but nothing here can’t be done with the free web version.
Here is a very basic of what I mean by groups and outer shell, (which is available in the free version) think of it as the glue stage for each step.
Here I have put four groups together, then glued then using Outershell, then opened for edit and use edges and pushpull to cut, I remove the other edges and colour so the endgrain is still obvious.
GIF 15-04-2024 1-28-47 PM

Yes, I knew what you were trying to do, but I would approach it very differently in SKP to figure out and come up with new patterns.

Good luck!

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