Why It's Important:
The design of this airplane yields an airframe that is inherently light already. The way the components are oriented on the print bed also makes them inherently strong. We highly recommend that you use Lightweight PLA for the construction of the plane due to the critical nature of the CG. To ensure optimum strength and lightness we customized our print settings. This is important for two reasons. Obviously a lighter airplane flies better, but also if you have ever looked at the side profile of the Fokker DR1, there’s really not much to the airplane at all in front of the wings. It is far too easy to end up with a tail heavy model and outside of a weighted prop spinner - a completely non scale solution, there is little opportunity to correct this situation. Pay close attention to your weight and balance to ensure a beautiful flying model.
Lightweight PLA:
This stuff is expensive at first glance but once you understand how it works and you again get your printer settings dialed in you may never want to go back. Embarrassingly, I burned through two solid rolls of this stuff before I stopped and took the time to understand exactly how it works. Once I did, I fell in love. Because of the foaming nature of this product it has the ability to produce parts that are significantly lighter in weight. Those parts happen to be somewhat more like balsa wood and are easily sand able as well. As a weight comparison, I printed the horizontal stabilizer with both materials. The weight of the LW PLA part came in almost 50% lighter! Considering that these parts are the furthest away from the CG of your model that’s a real win. Really this stands to reason because in order to produce parts with a foaming filament that were not over extruded I dialed the extrusion down to 65%. Now suddenly this stuff doesn’t seem so expensive anymore. A 1 KG spool at these settings basically will print the equivalent of two spools of normal filament. I highly recommend using it. Get It here:
Fine tuning your filament:
Cura now contains some great tools to assist in fine tuning and testing prints on your specific filament. We recommend that you learn about the Cura print tower and stringing test functions that it now contains to test and tweak your filament for optimum temperature and retraction settings. These can be found on the "extensions" tab then "post processing." Get these dialed in before printing parts. you will be glad you did.
Horizontal and Hole Expansion:
This is absolutely critical for this model. So many of these parts are designed to interact with each other. Arriving at an exact finished print dimension is critical. Use the image below as a reference in Cura on where to make these setting changes. Also, download and use our free test gauge to dial this setting in on your machine and filament. Each machine will require a different number so make an adjustment to this and run the print test gauge file as a test. Continue to adjust until you get a nice "lego" like fit.
Our Cura Print Settings:
Unlike many other model planes out there, the parts of this model were not created as single wall faces but rather as solid bodies. You will be relying on an unusually low infill and wall settings to create very airy hollow structures where all the strength of the part is at the outside of the shell exactly where it needs to be. This setting will apply to the vast majority of the parts with the exception of the wing, landing gear struts, and motor mount.
Infill: We have had success dialing the infill all the way down to 10%
Wall thickness: Set to 1 layer.
Top / bottom: Also set to 1 layer with 1 finish layer.
Lightweight PLA Settings:
The above settings have also worked with LW PLA but you will have to experiment with your temperature and extrusion settings. As a starting point for our machine we ran at 230C and 65% extrusion. yours will differ so experiment before diving into production. We also have discovered that we can afford to put some more infill back into these parts and still be ahead of the weight curve over traditional PLA. Start at a 15 percent setting and experiment up from there.
Tiny Stringers:
In the case of printing the smallest fuselage square stringers, these parts while plenty strong are just too flexible. Experiment with dialing the percentage way up to 60% also dropping the temperature on these parts will create higher density. I have run these successfully at 105C and 95% flow. At that setting, LW PLA behaves more like normal PLA.
Motor mount:
We recommend normal PLA or PETG for this part.
Wall settings: Set to 3 layers.
Infill: Set to 75 percent.
Top / bottom: Set to 3 layers.
Landing Struts and Wing Struts:
We will beef these up just a little bit, but don’t go crazy here because the real strength of these very thin little parts will be a small 2 millimeter carbon fiber rod that will be inserted through the finished print. Because of this, pay special attention to your Horizontal hole expansion settings as mentioned previously.
Infill: 50%
Wall Settings: Set to 2 layers.
Top / bottom: Set to 2 layers.
Conclusion:
That is it for now on the print settings. Check the main blog here for the next steps. Feel free to reach out to us with any questions. We will attempt to clarify the construction blog including your input as much as possible.
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