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7. Computer Controlled Machining

This week’s task is to make (design+mill+assemble) something big (~meter-scale) extra credit: don’t use fasteners or glue extra credit: include curved surfaces

Individual Assignment

  1. When I started this assignment I thought that I would design and produce some shelving for my desk. It’s in need of some organization. I had visions of a grand hutch to go on my standing desk that would have space for my 34” external monitor and some books. I started designing in Fusion 360.

  2. The basics of the design are below.

    1. OfficeShelves-6
  3. I had planned to tweak it a bit to make it more useful, but thought I would make sure I could turn it into a useable CNC file before I got too far. With the copying and pasting that I did to create the design, I had a difficult time figuring out how to make the tabs and pockets on a sketch layer so that I could export the files as DXF that I could load in to Aspire for the ShopBot CNC.

  4. To better understand the process of making a parametric model with press fit joints I designed the sides of a simple bookshelf that was fully parametric.

    1. I started off with a simple rectangle and added parametric tabs.
      1. ShelvesTabs
    2. I kept designing and came up with the complete side with lots of parametric options.
      1. ShelvesTabs2
    3. Here are the parameters that I was able to control (Tab Placement, Tab Width, Wood Thickness and Shelf Height).
      1. SideSketchwParameters
  5. Here is the final design of the simplified bookshelves

    1. Final Shelves
  6. With the sides designed I turned my attention to how to convert the two sides into a DXF file that I could load into Aspire and ultimately the ShopBot CNC. First I tried a simple “Export DXF” option and that didn’t work as intended, so I kept trying. I Googled “Fusion 360 3D Model to Lay Flat for CNC” and found a useful tutorial.

Lay Parts Flat in Fusion 360 with Arrange Feature

  1. In order to lay parts flat in Fusion 360 the parts must be components, so I needed to convert the shelves that were ‘bodies’ into components. That was an easy step since I just needed to right-click on the body and select ‘Create Component from Bodies’ option and it will create the correct file that can be utilized with ‘Arrange’ feature.

    1. Arrange1
    2. Arrange3
    3. Arrange4
    4. Arrange5
  2. Now that I had the parts flat, I tried to export a DXF and import it into Aspire, and it wasn’t quite right.

    1. Aspire-Export DXF Bad
  3. Consequently, I did some additional research and found a tutorial on how to make a projected sketch on the XY plane from a solid body that could be used to create the CNC file. Prepare a Fusion 360 file for Laser Cutting

  4. Now that I knew how to create the correct DXF, here is what it looked like.

    1. Project for DXF
  5. I loaded the projected DXF file in to Aspire and was pleased with the results.

    1. Aspire-3
  6. Now I need to add shelves to my design along with the dogbones for the press fit shelves using the Lay Flat feature in Fusion 360.

    1. Shelves Using Arrange Feature
    2. Now importing the DXF to Aspire results in-
    3. Aspire-4
  7. I have everything properly arranged in Aspire, so it was time to make the two required toolpaths (Inside and Outside).

    1. Outside toolpath with tabs.
    2. ShelvesOutsideToolpathAspire
    3. Inside toolpath for dogbones.
    4. ShelvesInsideToolpathAspire

Cutting the Shelves

  1. After exporting the toolpaths from Aspire, I followed the Charlotte Latin FabLab Alpha ShopBot Workflow March 24 2023 when using the ShopBot.
  2. Here are some photos of the setup and cutting process on the ShopBot.
    1. ShopBot1
    2. ShopBot2
    3. ShopBot3

Assembly

  1. Once the pieces were cut on the CNC it was time to assemble them.
  2. Here are assembly pictures.
    1. Assemble1
    2. Assemble2
    3. I stacked the two side pieces on top of each other and realized that the one of the dogbones weren’t the same on both pieces, so I need to rework it a bit. I used a cordless drill with a 3/8” bit to expand the dogbone to make it match. I also used the correct piece as a template when drilling.
    4. Assemble3
    5. Once the dogbones were corrected, I assembled the shelves with a wooden mallet, and they generally fit well. As you can see from the pictures below, there was a slight bow in the wood with a slight gap on the top.
    6. Assemble5
    7. Assemble6
    8. Here is a picture of the final assembled shelves.
    9. Assemble4

Learning

Overall this assignment allowed me to improve my CAD skills and learn more about the capabilities of the ShopBot CNC. I learned about assemblies and lie flat commands in Fusion 360 and how to make complicated toolpaths in Aspire to use in the ShopBot. While the slight interference fit I planned for generally worked with the final assembly, the bow of the wood allowed for some slight separation. Next time I will take into account the bow of the wood when assembling. If I had switched sides for the end pieces, it may have worked better.

Link to my files for the week.

Group Assignment:

Link to our group assignment.