Relief Map on a CNC Router

Supplies

Step 1: Download a STL Version of the Area You Would Like to Cut

I wanted to cut a relief map

Search online for Terrain2STL or visit jthatch.com/Terrain2STL, pick your area and choose your settings.

Settings I used:

Box Size: 840 (I've tried larger ones in the past and my computer really struggled)

Box Scaling Factor: 1

Box Rotation: 0

Vertical Scaling: 4

I maxed out the vertical scaling to exaggerate the mountains.

Water and Base Settings:

Water Drop: 5

Base Height: 1 Again, I wanted to maximize the contrast in my mountains.

When you get everything just right, you are ready to click Generate Model. Take note of where you saved the file.

Step 2: Import Model Into Fusion 360 and Reduce Faces

Open and extract your .stl model.

Click File --> Upload, and navigate to the location of your downloaded model.

Click the Show Data Panel at the very top left of the screen if your model doesn't load automatically.

When your .stl model is first uploaded into Fusion it should look like the Image 1 above. 

This is comprised of thousands and thousands of 'faces' (over 260 thousand for my model). 

In order to assign advanced toolpaths, we first need to convert it from a mesh of faces into a solid body.

First click the drop down under Bodies to display MeshBody1. Right click MeshBody1 and click Properties. 

This should display a Facet Count among other info. To convert a mesh body into a solid body, Fusion 360 requires fewer than 50,000 facets. 

Chances are that your model has much more than that, so we will need to reduce the number of faces.

Next navigate to the Mesh tab at the top of the program. The first thing we will need to do is select 'Make Closed Mesh' under the modify tab. 

This is not always necessary, but I have run into trouble when converting the model if this step is skipped. 

MeshBody1 should automatically be selected, if not click MeshBody1 under the Bodies folder on the left hand side.

I used a Rebuild Mode of Standard and a Density of 256. 

You may want to reduce the density if your computer struggles to execute this command, but a low density may soften some of your scene's detail.

A new MeshBody should have been created, named MeshBody2. 

Delete MeshBody1 to take some of the strain off your computer.

Next click the arrow beside Modify and select Reduce. Once again your model should automatically be selected, 

if not make sure to select MeshBody2 from the left hand side. Use a Reduce Type of Adaptive, 

and change Reduce Target to Face Count. Enter 50,000 or less for the target face count . 

This will remove some detail from your model, but hopefully not too much.

Step 3: Scale the Model and Convert to a Solid

Return to the Manufacturing workspace.

Under 3D Toolpaths select Adaptive Clearing. Tool selection, RPM, and Feed Rates will vary greatly depending on your machine, material and workholding. 

The above parameters are for cutting a 4" x 5.5" piece out of walnut with a 2 flute 1/4" sharp endmill.

After the adaptive clearing select the Parallel toolpath under the 3d menu. used a tapered ballnose endmill from Amana Tool Item #46282-K and the settings above

It's up to preference, but I found it was easiest to place my origin at the bottom left of the part. 

The default origin is at the center of the part. If you'd like to change it right click Setup1 and select edit. 

On the Setup tab select the bottom left corner of the stock using the stock point snap point. 

Make sure that the Z level remains at the top of your stock

You can now simulate your toolpaths. If you click on one it should give you a preview of the cut path. 

If you select both (hold shift) then click the simulate button at the top in the Actions menu you can do a simulation that includes the stock removal

Step 5: Setting Up the Router and Holding the Part

To http://jthatch.com/ for the awesome Terrain2STL tool.