Foil Assist Build - Queensland, Australia

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3D Printing Notes
After playing around and doing some test prints… then doing a lot of research, I have learned for max strength…

  • Increase wall thickness (number of shells), minimum 4 layers (as suggested by @hangloose: No Epoxy. 7 walls and 60% Infill and @V_S : No Epoxy. 6 walls and 66% Infill). Increasing infill does not make nearly the same strength (rarely need to go over 50%, and doing so risks print issues).
  • Most obvious is use lengthwise prints eg across the bed, as opposed to layers (vertical) along the longest axis (or whichever length needs most strength) - layer adhesion is the issue - which is greatly improved by the following…
  • Increase layer/extrusion width - either a bigger nozzle or for example (in Cura) Line Width: 210%. The bonus with this is significantly faster prints.
  • Keep layer height less than 1/2 width of nozzle - in testing for a 0.4mm nozzle a 0.15 layer height was strongest. Bonus is a smoother print.

I found all this info from the amazing youtuber Stefan of CNCKitchen:

Also worth noting:

  • I am using an Ender 3 V2 with Cura and using profiles from youtuber CHEP/Filament Friday eg the latest strong print is using his FF5.0_Good (0.2) then applying settings mentioned above (layer height: 0.15, Line Width: 0.84, Infill 60%, Wall Line Count: 7). Also using Tree support type (this is giving me cleaner prints over the standard one)
  • Good discussion on 3D printing here: 3d printing material for motor mount
  • Some people are using epoxy or other glues to fill in voids - but as mentioned above, others are getting reliable strength without - just good print settings and material.
  • Got PLA super strong with settings mentioned above. Its so strong I can’t even remotely break/deform the thin propeller blades!
  • PETG it prints beautifully… but requires specific settings (see below).
    Initially I was finding that under stress its seeming to separate on thin parts (prop blade) with compound curves. However solid parts are excellent - very strong. I was discussing these issue over on this post. .
    I have finalised my settings for this and it is very strong now - see here
    For PETG and PETG-CF - very strong, cannot split walls or layers!:
    • Temp: 230C
    • Speed: 50/25mm/s
    • Flow: 105-115% (default was 95% but this yielded poor wall and layer adhesion)
    • Layer Height: 1.2-2.0 (1.5 is my pref for looks and strength)
    • Fan: 20%
    • Retract 5mm/45mm/s
  • Apparently FDM is considered useless for waterproofness - so some kind of post- processing eg painting or a coating of epoxy is required. Also avoid sharp corners - so use rounded corners/fillets where possible.
  • Regarding suitability for use in water - the following is from someone who does 3D printing for a living:
    “Petg-cf or nylon would be my recommendation for an efoil. Tpu is very hygroscopic so not great for applications involving water. It’s definitely one of the most durable filaments and could work but may not come out nice with a complex shape that has thin walls”
  • The following is a reply from BambuLabs when asked which would be their recommendation for our use:
    “We would highly recommend you PAHT-CF. Bambu PAHT-CF is a composite of PA12 and carbon fiber. Inheriting the advantages of low water absorption from PA12 and high-performance carbon fiber, Bambu PAHT-CF offers excellent mechanical and thermal properties that can be maintained well even when the prints get wet. Higher Z adhesion layers and flexibility make it ideal for creating engineering parts such as functional prototypes, machining fixtures, injection molds, jigs, and low-volume production parts.
    But it cost a lot. If you are in a tight budget, PETC-CF, PA-CF are also good choices.”

Other useful resources:

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3d printing material for motor mount