Part - Cowl 1
Introduction
I focused on and printed
Cowl-1 first because I felt it was going to be the hardest to CAD up AND to print. It was and is. It has some serious challenges in both categories. I did not want you all to start with this one because, it is the most likely one to cause you troubles printing and I didn't want you to get a bad taste in your mouth right off the bat.
The main technique to make it easier to CAD up is it is a shell body. In other words, there is no inner wall to define the inside of a printed wall. In Cura everything inside is fair game. Which means, you can't use Infill unless you want to fill the whole thing up. Obviously, we don't so we define how many "wall" lines we want in the model. Since this is purely cosmetic, we only want one wall. However, we do want reinforcement at the front ring to keep it nice and round AND we want to have a nice contoured, scale-looking inlet to feed that hungry turbo-prop engine.
If you'll note in picture above, the orange coloration above signifies the outside of an STL facet. The green indicates the inside. You'll note the lip rolls over and back into the hole. The fact that Cura was able to handle this as I was hoping surprised me. It is printing a single wall as it comes from the back end toward the front and suddenly sees this inner lip sprout out of nowhere and starts printing an interior wall without requiring any supports. This finally meets back at the front tip. I was hoping for this for future war planes like P-51 and P-38 which are critical to their look.
Another feature of this specific print uses
Adaptive Layers. With this feature, Cura notes the slope of the wall from layer to layer... for instance the tops of the exhaust pipes as they merge into the central body. Note in the image below the legend shows the layer thickness varies from 0.15 to 0.33 mm. At the top of the exhaust it is at the minimum while at the top edge (that is near vertical) it is at the maximum layer height.
This feature has two advantages. (1) It makes the layers smaller so the printer has a higher resolution and curve is smoother since the steps are smaller. (2) Because the layers are smaller, it helps on shallower overhangs. In other words, where you might only be able to handle 45°-50° overhangs at 0.25 mm thick, you might be able 70° overhangs at 0.1 mm thick.
Post Processing
There is one problem left that I haven't figured a way to help in either the CAD work or the Cura settings. Note at the top of the exhaust pipes. The over hang is approaching the horizontal. The picture below shows the trouble area and experienced people will say, "
That won't work, it'll just shoot plastic down inside or it needs supports." Actually, the image isn't quite realistic since the lines in reality are 0.4 mm wide. It actually prints, but it does have gaps in it and almost looks like a screen door when it comes off the printer.
For me, it was no big deal... I didn't expect anyone else to want a Turbo Storch. I simply use a piece of masking tape on the inside and use ABS melted in Acetone to the consistency of Elmer glue. I paint it on and fuse into and is the same plastic layer like the printed part. Problem fixed. Now what you all might do using PLA or PETG... I'd sure like to hear your ideas. OR... Do you have CAD or Cura suggestions that I can try. I'm all ears. This print weighs 4 grams in ABS.
Printer Settings
- Quality
- Layer Height = 0.25
- Initial Layer Height = 0.25
- Line Width = 0.4
- Walls
- Top/Bottom
- Top/Bottom Thickness = 0.0
- Infill
- Material
- Printing temperature is highly material specific. 3DLabPrint recommends running PLA hotter than normal to give better interlaminar strength. They suggest nozzle = 230°C, bed = 56°C
- Speed
- Print Speed - is mostly tied to material used and even printer design. I use 60 mm/s.
- Travel
- Enable Retraction = On
- The rest of the setting are very printer specific. My direct drive Prusa uses a retraction distance of only 0.8 mm. It is my understanding that Boden type printers have a much larger retraction distance. Hopefully you have those kind of setting tuned in for your printer.
- Cooling
- Enable Print Cooling - Off. Cosmetically, having it on is better, but 3DLapPrint recommends turning this off to keep more heat in the plastic to cause it to fuse better giving more strength between layers.
- Support - Off
- Build Plate Adhesion
- Type = Brim
- Brim Width = 5 mm
- Special Modes
- Spiralize Outer Contour = Off
- Experimental
- Adaptive Layers = On
- Adaptive Layers Maximum Variation = 0.1 mm
- Adaptive layers Variation Step size = 0.01 mm
Link to Resource is available at -
https://forum.flitetest.com/index.php?resources/inqd-turbo-storch-cowl-1.361/
