3D Printing At Discovery Charter School – Part 8

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By David Lewis

“Refining the build and tuning the robot”

Our next step beyond doing spoons, tactical sporks & evil knives, was to start developing more complex systems and more precise builds. Vernon took a shot at designing a “gearbox” that is taking a good deal more time and effort than anticipated. The first printing effort looked like little more than a pile of thin green spaghetti.

Riley decided to take a shot at the complex printing of the “corner pieces” that Chylld has posted on the Thingiverse site. This process was an education in:

• Patience
• Persistence
• Problem Solving

The first print highlighted how crucial having everything tight, carefully aligned & paying close attention to extruder heat for the different colors of the ABS are. From the picture it is clear that we had an issue with belts (or as it turned out, the shaft) slipping, extruder heat too high and a need to make sure everything was tight before we started a complex print.

There is huge “stair stepping” due to slippage of both a belt and the “Y” shaft within the connector to the “Y” motor. There was also actual “burning” of the material because we didn’t adjust the heat correctly for the green ABS. We corrected the belt, carefully re-torqued many of the bolts and printed again. This time there was no burning, but about ½ way through, it started “stair stepping again. We killed the print and looked hard at our set up. The belt appeared tight even though the print was learning off to the right.

We started manually moving the carriage and found an interesting “slip” about 1/3 of the way through the full range on the Y axis. The Y shaft was slipping against the set screw. Even after tightening the set (or grub) screw down, it was still not happy. Coming from the school of “Irish” engineering, I simply ground a flat on the shaft and added a touch of Locktite – problem solved.

The next attempt at the “corner” came out better than we could have imagined. The unit had great alignment, crisp holes, and a top finish that looked like it was sanded and polished. There were some “slubs” that needed to be cleaned off and a little clean up under the raft before it was ready to show off to folks.

We made a lot of progress from the first version to the third.

Riley had a chance to bring his samples of the corner into my office today and one of the engineering managers asked if he could do a cut-away of one of the new ion sources that we are developing. No one wants to sacrifice any of the prototypes we currently have in order to show folks the internal workings, so this is a perfect project for the DCS Herd to take on. By producing a couple of ABS models, the kids will contribute to the engineering effort and also build their portfolio.

While 3D printing and rapid prototyping are nothing new for those of you kind enough to follow this blog, these techniques are really new to a lot of folks, even those deep in R&D like a lot of my colleagues here. It also looks like that there is something about a well-spoken (IMHO) 13-year-old offering the service and explaining it all that is completely non-threatening.

Stay tuned for a peek at their work on the ion source.

Part 9 >>