How to Make a Terrain Model with a CNC Machine


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Here is a relatively simple project I did which involves making a terrain model with a CNC machine. In the pictures below, you can see a scaled down model of Mt. Everest. It’s slightly under 6″ from one end to the other.

CNC Made Terrain Model of Mt EverestCNC Made Terrain Model of Mt Everest2Terrain Model

Software Needed

For this project, I used Google Earth (free), Sketchup (free), and CamBam+ ($149).

In the not too distant past, this project would have been considerably more difficult to achieve, but, thanks to these three software programs, it was a piece of cake.

1. Loading the Terrain into Sketchup

The first thing I did to make this model was navigate to Mount Everest in Google Earth.

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After finding Mount Everest, I then zoomed in to prepare for loading it into Google Sketchup. (This won’t work when zoomed out too far.)

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Next, I opened Google Sketchup and clicked the “Get Current View Button.” img14 Note: If you can’t find this button, go to View >> Toolbars and make sure that “Google” is checked off.

Clicking the “Get Current View button” will load what you see in Google Earth into Sketchup.

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With the current view loaded, I then clicked the “Toggle Terrain” button. img19
Below is the picture of Mount Everest after pushing this button. Obviously, this isn’t the whole mountain.

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To load more of the mountain, I had to go back to Google Earth, navigate to a slightly different position, go back to Sketchup and click the “Get Current View” again. In this picture, you can see the mountain again after I loaded a couple of more views.

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After repeating this process several times more, I managed to load not only the top of Mount Everest but also some of the surroundings.

everestfinished []

2. Scaling the Sketchup Model Down

With Mount Everest’s terrain loaded, I next needed to scale it down to a manageable size (It is Mount Everest after all). I started by first clicking and dragging over the terrain to highlight the individual groups.

redselect []

Next, I right clicked the red blocks and then clicked “Unlock.” This turns the blocks to the color blue.

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I then right clicked the blue blocks and clicked “Explode”.

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Finally, with the mountain highlighted, I right clicked one last time and clicked “Make Group”.

group []

At this point, the model is ready to be scaled down.

From here, I proceeded to shrink the model using the scale tool img36. In the left picture, I have it shrunk down to about man size. In the right picture, I almost have it shrunk down to its final size of about 6″ in diameter. You can see that I drew a circle for reference.

mansized [] circle []

3. Preparing for the Terrain Model for Export

At this point, the model is mostly finished. What you do from here depends on your own personal preferences and the dimensions of the material you are cutting the model out of, but here is what I did.

First, I extended the circle vertically and erased img48 the parts of the mountain that extended past the circle. Notice that I hit “K” on the keyboard to toggle hidden geometry on. This makes it a little easier to see what needs to be erased.

circlecut []

Before finally exporting the model, I moved the top of Mount Everest so that it was touching at Z = 0. Notice also that I made a platform for the mountain to sit on.

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4. Exporting the Terrain Model

Since I am sending this model to CamBam+ for generating the toolpaths, I will need to export it as a STL file.

There are actually a few different ways you can export STL files from Sketchup. The easiest is to use one of the two plugins that I wrote about on this pageNote: For this projects, I used the Su2stl.rb plug-in.

Another more roundabout way is to use the method that I wrote about on this page.

5. Generating the Toolpaths in CamBam+

Here is the model after loading it into CamBam+.

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Here it is once again after the toolpaths have been generated. The top picture shows it with the roughing passes disabled so that you can see the finish passes.

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[bad]

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Here is the CamBam+ file if you want to see the settings I used for generating these toolpaths. Everest Model.zip I’m not saying that these setting are the best, they are just what I decided to use.

If for some reason you want to try and cut this model out with your CNC, you might want to stop it near the end when the Z axis is close to -1.46. The reason why is because CamBam+ seems to generate a few stray G-code lines that will ultimately damage the model somewhere past that point.

This model in particular seems to be very challenging for CamBam+, and I had to experiment with several different toolpaths before I found something that worked well.

I have found that Cut Viewer Mill is indeed a very useful piece of software to have. With it, you can quickly simulate cutting the part out with your CNC to make sure that it will turn out the way you want it.

6. Cutting out the Terrain Model with my CNC Machine

Here is a quick time lapse video of this model being cut out with my CNC machine.

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