Tuesday, September 16, 2014

A couple of recent 3D printing successes

With a few last-minute improvements I've been able to substantially improve the performance of the printer. I slowed the stepper motor to reduce vibration, and I allowed a settling time after each motor movement before exposing the next layer of resin. I cleaned up the build platform, it is now a sheet of aluminum epoxied to the plywood. (And of course, within a couple of prints, it has gotten covered with a sheet of cured resin. Best laid plans...) I had been trying exposure times that were too short, so I went back to 60 seconds per layer.

If you'd like to see these prints and others, and the printer that made them, come to Maker Faire NYC this weekend at the New York Hall of Science in Queens, NY.

Here is a chess rook. It has an interior spiral staircase. The windows are a bit misshapen and the bottom flat surface is covered with a big glob of cured resin. I don't know why those things happened, but the detail on the parts that came out well isn't too bad.
This is a dodecahedron, one of the five Platonic solids. In the days of ancient Greece, this shape was the cause of some controversy because it could be used to prove the existence of irrational numbers, which ticked off Pythagoras something fierce. This was posted on Thingiverse, as was the rook.

More shapes to come soon, if all goes well.

Sunday, September 07, 2014

Finally, the thing is printing

Tomorrow I start a new job with Formlabs, a 3D printer company, and I'm psyched about that. Unfortunately, however, one of the conditions of my employment there is that I cease development on my own 3D printer. I spoke with their attorney and it all makes sense, it's the right thing to do, because my printer is entirely open source and they are selling a proprietary product. If I were to continue developing my printer, it would be too easy to unintentionally include pieces of their technology. So tonight I am putting the finishing touches on the Github repository.

Today was the first time I made a successful print with this printer design. I had hoped to print four dodecahedra at once. But I had some crud on the surface of my build plate, and I hadn't stirred the resin before printing, so only one of the four came out really well. Another was misshapen, and two of them never came together at all.

 Here are the two that were at least coherent solids. I think with a little more learning and practice, I'll get to where I can make four that all look as good as the one on the right.
Here is the setup I'm using. If you've followed this blog, you'll recognize the stuff on the bucket. The box-like thing overhead was quickly cobbled together when I realized that my mirror wasn't reflecting enough UV light to make the resin cure properly, because the mirror's glass isn't transparent enough in the UV range. To remove the mirror from the optical path, I needed to put the projector directly over the bucket, pointing down.