From SketchUp to CNC Fabrication

This video series shows how to get from CAD, to CAM, to a CNC fabricated product.  The tools we will be using are SketchUp for CAD,  CamBam for CAM, Mach3 for gcode reading/CNC control, and a CNC router (greenBull from BuildYourCNC.com) for part fabrication. 

Keep in mind during this tutorial that the particular hardware/software tools, materials and application of these instructions will vary from person-to-person, region-to-region, and project-to-project.  You may be using a different CAD program, CAM program, CNC control program, CNC machine, material sizes and fastening methods, and you will likely be fabricating a wide variety of products in the end.  So, keep in mind that this tutorial is one of many different ways of going from CAD to final product.

In this example, we will be fabricating a cart for our blackTooth laser cutter (http://www.buildyourcnc.com/blackToothLaserCutterAndEngraver.aspx).  This cart will allow us to store materials and easily move the machine from place to place.  We will be using 4ft x 8ft sheets of 3/4 inch birch plywood for the main structure material, joined with machine screws and cross dowel nuts.

Notice that as we are modelling the separate pieces, they are made into components.  Doing so will make your life much easier in the CAD process.  It will allow you to painlessly select, move, and modify the parts independently from the rest of the model.

Components in SketchUp are also useful because when you create a copy of a particular component and make a change to one, those changes are automatically updated in all of the clones of that component.  This can be useful when designing for lossless manufacturing (manufacturing with near-zero waste product).  With your model mocked up in 3D, you can create copies of all the components and lay them out flat onto a rectangle the size of the stock material you will be cutting from.  From here, you can modify the original model (which will update changes in the components laid out onto the virtual stock material) in order to occupy the remaining space on the stock material.

At the end of the CAD process, we export a dxf file that we will import into CamBam.  If you do not have SketchUp Pro, you will need to install a plugin to allow you to export in dxf format.  Here is a video showing where to find and how to install this plugin:

Here is the link to download the plugin:
http://www.guitar-list.com/download-software/convert-sketchup-skp-files-dxf-or-stl

Step 2: Applying Machining Operations and Creating G-code with CamBam

When you first import your dxf file into CamBam, there may be a few things that you need to tidy up.

Any circles in the model will likely have ended up on the opposite side of the origin as they were modeled in.  This can be remedied by simply selecting all of them, and mirroring across the axis they were flipped on.

Also, it is likely that geometry like rectangles were read in CamBam as being constructed of separate lines.  Select all of the geometry in the file and clicking Edit -> Join.  Enter a tolerance such as 0.001".  This will join only the lines that are within 0.001" from eachother, and will leave the rest of the geometry alone.

Once you have applied all of your machining operations, save the CamBam file.  Now export the g-code (*.nc file).

Step 3: CNC Fabrication and Final Assembly

With the g-code that we generated with CamBam, we are able to run the CNC machine with Mach3.

When the machine is finished cutting out all the parts, we break the holding tabs using an oscillating multi-tool, and then shave them off using a table router.  After this, we drill the edge holes using a custom jig (which we also fabricated with our CNC machine).  After this, sanding the edges is optional.  Then, it's simply a matter of putting the pieces together!

Hope you enjoyed this process..  now go out and make stuff!

Thanks for watching!
- The BuildYourCNC.com Team


www.BuildYourCNC.com

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