It's been some time since my last post, sorry. I do however have some progress to report on.
I took some time last week to start digging deeper into getting the 3D printer working. YouTube and Google are well known sources of information (as everyone knows - duh!) and there are tonnes of tutorials and "for Dummies" content out there, including how to calibrate and start printing with this early generation HicTop Prusa printer.
First thing I learned was that any design 3D model must be converted to G-code by intermediary software. G-code is the machine language used by 3D printers, milling machines, etc. to interpret the 3D design in a way that can be understood by the machine, i.e. how to move the stepper motors in each of the 3 axis, how/when to extrude the filament and the path the print head must follow.
The software that does this for 3D printing is generally referred to as "slicer" software.
I loaded up the official 3D test file from the HicTop website which comes as an "STL" file. The test file is a 4 leaf clover shape. In a nutshell, an STL file stores information about 3D models. This format describes only the surface geometry of a three-dimensional object without any representation of color, texture or other common model attributes.
These files are usually generated by a computer-aided design (CAD) program, as an end product of the 3D modeling process. “.STL” is the file extension of the STL file format.
The STL file format is the most commonly used file format for 3D printing. The true meaning of the file extension .STL has been lost to the mists of time.
It’s widely believed to be an abbreviation of the word STereoLithography, though sometimes it is also referred to as “Standard Triangle Language” or “Standard Tessellation Language”.
With the file downloaded, I ran a free slicer program called Cura. Cura has many settings to customize a print but for this test, I went with the defaults with the exception of the filament diameter which I changed to match what I had loaded in the printer. Cura then converted the STL file to G-code, which was then exported to a SD card. The SD card gets placed in the printer and I started my first print (which as you will see below turned out pretty good!).
I asked Cura to add a base to the print called a "raft" - this is a small lightweight layer that is laid down first, giving a good base for the print to adhere to:
With the raft complete, the printer moves into position to create the 3D print, guided by the supplied G-code information:
Layer by layer, the extruder lays down a steady stream of melted filament, building upon the layer before it. I captured a video of it working here. This isn't sped up, it actually works at this speed (sorry about the noise!)
The test model is actually much taller, but to save on filament (and time), I stopped the print after a while as I was satisified everything was working as it should. I'm pleased as how well it turned out - nice and smooth and well defined shape wise:
Excited to try another print, I went back to the internet to find a 3D model for an airplane part I can use for my build. I'd seen someone had posted a trim cable fairing for Zenith aircraft. This fairing works as a passthough and strain relief in the tail of my airplane, or anywhere else that might be suitable.
I downloaded the free model (thanks to 3D model sharing site www.thingverse.com) and upoaded it into Cura Slicer.
Instructions from the original 3D modeller said they had best results when they inverted the model for printing and adding support structures. Support structures are somwhat like a "raft" described above and are used to support parts of the 3D model that overhang, preventing them from sagging or warping. First step is to invert the model:
Next I asked Cura to add supports. Here is a screen capture of the model showing all the layers including the supports (light blue). Cura allows you to show each layer of the print head path(in dark blue) - this is layer 133 of the print. You might notice adding support increases the print time and filament material used:
With the model exported to the Sd card, I started the printer again, this time with the new model I just converted with Cura. The following few pictures also show the second model in the set - a drill hole template that was included with the fairing model. It again starts with a raft for both:
The drill template is only about 15 layers thick, so when the printer finished it, I peeled it off the bed.
The printed item breaks away easily from the raft. The small scorch mark you see is actually extra filament that leaked out of the hot end print head and dropped on the printed piece (more on this later):
As I looked at the finished drill template. the printer chugged along building the fairing layer by layer. It's hard to capture the process as the bed and print head are constantly in motion:
Slowly the model starts to take shape:
Getting close to being complete, but you can see the print head is leaking badly!
After just over an hour, the printer head moves back to the home position and reveals the completed print!
Some room for fine tuning, but overall it seems like it turned out well!
I asked for the supports on the entire print as I didn't know any different, so Cura added them inside the throat of the fairing too. That will be easy to fix by cleaning it out with a small drill bit.
The print seems to have either warped or sagged at the one corner. It didn't affect the print in any way, but I suspect this requires another check of the print bed levels.
The main body of the print breaks away from the raft easily:
So do the supports. I'm printing these initial models with PLA (Polylactic Acid) which is different than most thermoplastic polymers in that it is derived from renewable resources like corn starch or sugar cane. Most plastics, by contrast, are derived from the distillation and polymerization of nonrenewable petroleum reserves. Plastics that are derived from biomass (e.g. PLA) are known as “bioplastics.” All the waste created by the supports and rafts can be recycled.
The base of the model is very smooth as it was last to print (model was printed upside down as per the suggestion online). The upper surfaces are a bit rough, but I think that's more to do with the support settings than anything and those can be adjusted.
The next models I tried printing were some edge markers. Unfortunately, they didn't work out well at all. I suspect I failed to set the model scale corrrectly and it looks like the extruder leak still needs to be addressed!
Overall, I'm really pleased that I got the printer working. I learned a tonne and I'm looking forward to doing some more with it. The possibilities are endless!
Back to the shop this morning to work on inboard slat #2. I followed the exact same process as the first slat and that experience made this one go much faster. I finished priming and assembling it back together:
After a hour or so in the slat box I finished riveting it together. Slat # 2 complete!
So, my completed parts picture is starting to fill in nicely!
I put both outboard slats aside for the time being and pulled the outboard slat skins out of storage to begin laying out the measurements for both of them. They follow the same method as the inboard ones, other than they are longer than the inboard slats. The inner skeleton remains the same, it's just shifted a bit more towards the centre:
A couple of hours later and the outboard left is substantially complete. Next up I'll continue the process and bend the trailing edge.
More to come with the 3D printer. I'm really stoked to try the 3D scanner and print something from that!
Another 15 hours done on the wings. Stay tuned for more, thanks for following along :)
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Husband, father and 911 dispatcher. Long time pilot with a licence that burns a hole in my pocket where my student loan money used to be. First time aircraft builder. Looking to fly my own airplane.