I Can’t Print This On My Replicator


Fused deposition modeling (or fused filament fabrication, if you want to avoid a nastygram from the legal eagles at Stratasys) is the process by which Makerbot Replicators, Afinia H-Series printers, Cubify Cube 3Ds, Repraps, Rostocks, and too many homebrew printbots to enumerate turn STL files from electrons into objects.

In FDM/FFF printing, the device lays down a layer of melted plastic, moves its build platform downward a tiny bit, and then repeats the process until the model’s completely built.

I’ve had my Replicator 1 for about a year now and I think it’s safe to say that I’ve put it through its paces. I’m pretty good at 3D printing with this particular FDM printer. I understand and work around its limitations, paying close attention to the 45-degree rule. FDM printers generally can’t print too large an overhang from one layer to the next; gravity interferes and the print fails with often hilarious results.

A few months ago I designed a model that I knew had no real hope of ever printing on an FDM printer. I wanted to see what Shapeways was capable of printing for under 20 bucks, so I built a Voronoi Seej bloxen and sent it over to them. A few days later this showed up in the mail:


You’re welcome to give it a shot yourself: just download the model. I’d be interested to see your results.

A cutaway view demonstrates why the Voronoi bloxen fails on an FDM printer. Most of the model’s OK, but it violates the 45-degree rule in a big way right at the top of the block.


The print at the top of the post was my first try at printing this bloxen on my Replicator. Those tiny Voronoi cells on the bottom of the model make it really hard to keep the bloxen on the platform. If any one of those little filament loops should detach from the platform, it’ll eventually get caught on the print head and catch another loop, and another, and another, and once your model is touched by His Noodly Appendage, it’s done for. Ramen.

Those little loops need to stick fast to the HBP So it’s back to FDM Printing 101: using a raft.

After a new slice, the Replicator had no problem keeping the base of the bloxen on the build platform.


A few minutes later it looks like the Voronoi pattern is holding up well. The mortises on the bottom of the bloxen are printing just fine. I’m starting to think this print might just succeed…


…aaaaand the 45-degree rule rules its ugly head and the print starts to fail as predicted right at the top of the bloxen.


As fails go, this one isn’t spectacular. Enough filament fell into the gaps to provide a scaffold for the top layers. The bloxen is still a fairly solid print, certainly usable in a Seej match.


So. Another failed print. But there’s still hope for those of us who haven’t been able to secure $30 million in venture capital funding. I’ve been corresponding with Dean Piper, inventor of the mUVe 1 printer. Dean took up the challenge of printing the Voronoi bloxen, and his resin-based printer knocked it out of the park:


I feel like home 3D printing is in the VHS vs. Beta stage of its history. On one side we’ve got superior market penetration of FDM printers, but resin-based machines like the mUVe are going to be the bots to watch in the next few months.

Erk. Almost forgot: this post is the latest in my continuing one-man crusade to make “Voronoi” the word of the year for 2013.

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