In the Fall of 2011 we were setting up the ShopBot booth at the NY Maker Faire and noticed some interesting plywood furniture across from us. It had obviously been fabricated on a CNC machine, with dogbones in the inside corners (which the designers called “snigglets”) and engravings on the tops to describe the process. Ted and I introduced ourselves to Anne Filson and Gary Rohrbacher, architects and University of Kentucky professors, who it turns out had been following our work via 100kGarages. Their design firm, AtFAB, had been designing furniture and making the files publicly available—using 100kGarages fabricators to get much of it made.
I’ve kept in touch with Anne and Gary over the years and have fabricated a handful of projects with them. We did the “Open Source Living Room” together at the 2014 Detroit Maker Faire that showcased Open designs of all kinds, from AtFAB stools and tables to the first 8×8 Shelter 2.0 design.
I also fabricated pieces for an exhibition they had at a gallery on the MIT campus in 2013, but the biggest project by far involved fabricating the furniture for MakerBot’s penthouse office in Brooklyn in 2013: the reception desk, meeting and conference tables, assorted chairs and desks, and even Bre Pettis’ office desk.
All these projects were fun to do so I was excited when I got a call from Anne a couple of weeks ago about a new project they were working on. They were both on sabbatical this semester and were working on some CNC fabrication instructions, and wondered if they could come to my shop in VA, talk a bit, and do some test cutting. I quickly agreed and made sure I had a couple of sheets of 3/4″ Radiata pine plywood and enough propane in the grill to cook hot dogs for lunch!
We started out by toolpathing a sheet in VCarvePro, our toolpathing preference, and cutting them out with bits that they had brought, an 1/8″ straight bit to mark the location of screw holes and a 1/4″ upspiral to cut out he parts. Although I generally cut 3/4″ plywood in 2 passes at 4″/sec, I wanted to be somewhat conservative for this and use the rule-of-thumb and cut each pass at the bit diameter, 1/4″.
I’ve written about my toolpathing and cutting techniques in a Medium post “A slacker’s take on CNC fabrication” and used basically the same system for these parts. There were a handful of small parts that I cut first using a spiral plunge, with a single tab at the start point. The rest of the parts I organized in increasing size, using a straight 4″ plunge and no tabs. The sheet finished machining in about 40 minutes, with Anne spending a little time cleaning things up on my assortment of sanders and Gary assembling the pieces.
At the end of the day, my wife and I joined them for a great seafood dinner at The Shanty in Cape Charles VA, and the next day we were off to Baltimore to visit OpenWorks in Baltimore.
While we were at OpenWorks, they had the opportunity to cut the same parts they had cut in my shop, out of ApplePly on the $60k Laguna CNC machine in the OpenWorks production shop. As you would expect, the parts from the Laguna turned out really nice and needed no sanding, but took a full sheet of parts to dial in the settings and required two passes each with downspiral and upspiral bits to get that quality.
When it was all over I asked Anne and Gary what they thought about the cutting and how they thought my 10-year-old ShopBot compared to the $60,000 Laguna. Gary said, “In the end, maybe I’m biased, but I think you can get just as good a finish with the ShopBot”
Anne said, “After dialing in the Laguna process, I suppose we could’ve quickly pumped out a huge job with a large number of sheets. Perhaps that’s where you’d find an advantage over a ShopBot? Or maybe not, if your shop and machine were organized for industrial jobs.”
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