My apologies for the break in posts, hopefully this post will makeup for it! This is something cool I’ve been working on this summer… a 3D printed spray bar for pseudo-kreisels. As far I know this is the first of its kind…
Using the free version of Sketchup 8 I built this model of an 8″ wide spray bar. As you can see there is a barbed fitting on one end to connect some 1/4″ tubing for the supply and 16 evenly spaced outflows to drive the current in the tank. The spray bar is angled to match the angle of the screen for a snug fit in the tank. There is also a flange on the far side of the model to help prevent it from being pulled off the tank. After printing 5 different versions of this model, I finally found one that worked. We used a MakerBot Replicator 2X to print the models.
This was the final print that made it all the way through, there were various printing errors: clogged print heads, ran out of material once, the print fell over, warped too much and the print would not stay on the table. Notice how in the final print above there is a tear-away support piece that I had to design in order to support the print. When you build an angled object you are going to need something to build on. I also ended up using double-sided masking tape to keep the print on the tray because sometimes the MakerBot would pull it off and start spewing plastic spaghetti strands all over.
Each print took six hours! A good overnight print job. I could watch it for about 30 minutes before I had to leave.
Here you can see me bending off the support and raft (the raft is the flat piece on the bottom and acts as an additional build platform, which can help prevent warping). The raft is from the Skeinforge slicing engine (the software that tells your bot how to print your model), I ended up choosing the Skeinforge engine because it gave a much better quality print. Since then, MakerBot has made some significant improvements to their own default slicing engine, but I still don’t like the complexity of their raft. The Skeinforge engine uses a nice simple grid type raft.
Here it is in use, pushing some little Mitrocoma medusae around in a 1′ pseudo-kreisel or “PK” for short. This print did leak a little bit at high pressure, I later found that I needed to properly face all of my polygons in the model before printing. Sketchup uses polygonal drawings that need to be converted to STL models, or triangle based models. If you don’t face your polygons properly then the printer will not print some faces and produce errors or rough surfaces. For example you can see the rough end of this print closest to the camera… that face should have been white in Sketchup, or an outer face… not a blue face which would be an inside face. This print was also slightly warped, something that could be avoided next time by using PLA plastic, a biodegradable plastic that is more rigid. When designing your own spray bar remember that you need the end of the spray bar to be below the water level, measure carefully when drawing your model in Sketchup. I hope this spray bar can serve as inspiration for more 3D printed applications for jellyfish tanks. If you come up with your own print, please send me some photos and I will post them here.