Keiichi Onishi

MAS.863 How to Make (Almost) Anything

Computer-controlled Machining

This week's assignment was "make something big" using Shopbot (CNC machine) cutting lumber. I have experiences in operating CNC machining using G-code, which is introduced as weird and obsolete in a class, cutting steel engine components. Cutting wood transporting DXF data to CNC machining was new for me, and felt quite efficient way.

Overall progress

I designed a TV shelf for my private use. As I wanted to make the shelf looks neat and sort of nature-friendly, I bought four 2x4 plywoods (0.5 inches thickness) at Home Depot. I designed CAD model with SolidWorks 2014 and exported DXF files, readable format for Shopbot VCarvePro. I successfully cut out every components but encountered a problem derives from material characteristics. The most outer layer of plywood was easily peeled off during process. After I cut out every parts, I grinded cutting edge using sanding papers, then assmebled the shelf by press fitting.

  • What: TV shelf
  • Material:2x4 plywood (0.5 inches thickness)
  • Design tool: SolidWorks; Shopbot VCarvePro
  • Tool: ShopBot
  • Co-creator: Vicky Chen from MIT Sloan Schoo of Management Class of 2016
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Step 1: Designing TV shelf with SolidWorks

I designed the TV shelf using SolidWorks. After I drew rough sketch, I designed five components of the shelf. To make it assmbable using press-fitting, I took account into measured actual thickness of material, which is 11mm, for the CAD design. I put fillets to each inner corner in the design in advance instead of doing that at IDC using ShopBpt software.

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Step 2: Cutting materials

I opened DXF files with VCarvePro to create tool path. What you need to first is closing all open vectors. I created my model in mm, not inches. So I set all parameters in mm changing all default values of work area size, cut depth, size of tabs. After that I saved tool path in inches (pretty important!!!), and cut woods. I used up and down hybrid milling cutter. Before you actually cut material, doing dry-run of machine is useful to make sure the tool path. Sometimes tool path goes beyond the size of material due to inappropriate X-Y position zeroing.

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Step 3: Sanding

After taking out all componets from raw material, I grinded cutting edge as almost all corner had burrs and some portion of outer layer of plywood were peeled off. I think this is the characteristic of plywood. If you want really clear finishing surface, you should not use plywood.

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Step 4: Press-fitting

Finally I got TV shelf assmebled by press-fitting! Special Thanks to Jose and Tomo!