<< Part 14
By David Lewis
Working on the RapMan
One of the challenges of the Rapman 3D Printer is that the initial parts are made of acrylic and are easy to break. When we began the build, I noted that the first exercise was to learn just how easy it was to break the pieces with too much torque. One of the beautiful elements of the whole 3D printing experience is being able to print replacement parts.
This week, under a fairly heavy production load for the school, we once again snapped the filament guide at the top of the extruder when we were changing media. You can see where it has snapped three times across the face of the piece starting at the “hardy hole” that fits over the peg at the top of the extruder head.
While it has been easy to glue the part back together, as the lab manager I had my fill. I asked Vernon to measure up the part and design a replacement in SolidWorks. From scratch using just calipers and dead-reckoning, Vernon came up with a first design and printed it out. You will note that there are a couple of problems with the first design in the next picture.
First, the “hardy hole” is not a square. Secondly, the larger hole in the top was not big enough to accommodate the conduit. And finally the bolt hole was off line. One problem we encountered was that the kids did not completely understand how to obtain dimensions with a caliper and then did not do an “eyeball” comparison of the SolidWorks model to the real thing. If they had, they would have seen the problem with the square hole.
A quick remedial lesson with the dial caliper, an adjustment in SolidWorks and 20 minutes later we got a much better piece.
This piece was correct in all the dimensions and fits nicely on the printer. While there are some small differences between the original and the new piece, there are no functional issues and the new one was done “free-hand” in SolidWorks. These kids simply blow me away with their willingness to try new tasks and their ability to make it work.
Part 15 >>