As the project is being wrapped up, for next year’s minor students to continue on, we can reflect on the progress made and of course list the areas which in our eyes have the highest potential for improvement.
During the initial week of the project progress seemed slow, with a quick visit to a metal workshop to receive some guidance on welding processes and settings. Deciding on which axis system to use and acquiring the right parts took longer than expected, luckily there was a Prusa supplier about 20 minutes away by bike!
Assembly of the machine took longer than the day or two we had planned. Plastic parts had to be remodeled and printed or machined out of aluminium to prevent meltdowns. Our heat shielding strategy in the end was more than sufficient enough. However a nozzle for active cooling of the work piece during welding intervals would be a great improvement. The cooling intervals could even be triggered by an infra-red sensor.
Calibration of the welding machine and axis systems went quicker than expected, once the torch was installed and the machine was moving it took less than an hour to find an optimal setting with regard to print resolution and quality. (Given the fact that we had visited the metal workshop gave us quite a leap in understanding which settings to use)
A day was spent researching various variables (travel speed, feed rate, voltage setting etc.) of the machine. This would be an interesting area to investigate with a scientific approach if equipment is made available to test the material properties of the metal structures.
The final frontier which we managed to cross before the project ended was software related. Plugins were written to optimize the g-codes, enabling our “extruder” to start and stop at the right times. Because we used Cura to control the 3D-printer we had to write the plugin in Python which made it impossible to delete the extruder codes in our G-code file because strings are immutable in Python. The extruder codes were superfluous and changed the travel-speed for which we had a fixed and optimized value. So we had to manually delete the extruder codes (E) and change the speed codes (F) in our G-code file.
Major improvements are to be made with respect to the software. For example:
Automatically removing the extruder codes and changing the speed codes. Altering the travel path of the extruder to reduce areas of concentrated heat (by avoiding overlaps and tight corners. Changing the initiation and termination position of the MIG welder are crucial to reduce the amount of imperfections or discontinuities, the pyramid is a great example of this.
As for pushing the physical limitations of the designs, we printed a single wall with overhang. Further research could be made to see up to which angles it is possible to print. The two, double walled pyramids show that hollow structures can be manufactured, but post processing on the interior is naturally limited. Suggestions for printing at acuter angles include using sand or clay as a substrate (a hypothesis for now).
To conclude it must be said that we had an amazing time working on this project. The learning curve was steep but rewarding and I do not think anyone on our team would hesitate to continue optimizing this fantastic machine. Hopefully we’ll see lots of similar projects pop up around the world!
– The Metalprinters