Week 07 :: Computer-Controlled Machining

How do we prototype quickly at scale?



1. Group Test run

I started this week by heading to N51 to measure the OSB stock, then sitting down with Chris Dewart to discuss file setup.


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Joined by Diana Mykhaylychenko, Mateo Fernandez, Nasibe Nur Dundar Arifoglu, and Niklas Hagemann, we found some scrap OSB to run a test file.
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In mastercam, Chris walked us through the file prepared by Jen O'Brien. A technique that was new to me was to set up a toolpath to drill pilot holes to clear the corners prior to doing the profiling cut.
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Since we used tape to hold down the edges of our irregular piece, we had to mill with the brushes up to not dislodge the tape.

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Nasibe vacuuming after the milling finishes.



2. Design Something Big

I'd like to use this week to upcycle a tatami mat. My apartment doesn't have a great place to store the mat, so I'd like to incorporate it into a piece of furniture.


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The plan here is to design a series of intersection profiles using friction fit joinery to act as the substructure for the chair. Polyester webbing will be used to strap the tatami mat in place.
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The design is constrained by the dimensions of the tatami mat. Here, I prioritized the seat height and keeping a flat back so that the design could be placed against a wall.
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The five pieces of the chair layed out on the 4'x 8' sheet dimension. Three layers were merged separately into mastercam. First, the profile curves of the pieces. Second, the surfaces for beveled edges. Third, boundary curves to constrain the toolpathing in the beveled zones.
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Toolpath setup consisted of four steps. First, the 1/8" drill is used to create pilot holes to secure the material to the spoilboard. Second, surface roughing of the bevels is done with a 1/2" ball for speed. Third, contours of the pieces are cut with a 1/4" downcut bit. Finally, a 1/8" flat endmill is used to clean up the corners.





3. Make Something Big

After design and CAM preparation, the job is ready to bring to the Onsrud.


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Full scale assembly of substructure. As I designed in Rhino, I thought of it as a chair, but in real life, it feels more like a couch.
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After the first toolpath runs, we could drive 3/4" screws into the spoilboard to hold the OSB in place.
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As we moved onto the second toolpath, there was a moment where the milling sound stopped. We lifted the brush to observe that the bit had broken, and so we paused the job.
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After this issue with the 1/4" bit, we decided to swap to a 3/8" downcut and regenerate the toolpath. The job proceeded without issues after this point, and I felt thankful for the automatic tool changer compared to the Intelitek and the Modela.

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After sanding the edges by hand to remove splinters, I brought the pieces from N51 to RPL to finish.