Need recommendation for easy-to-print engineering filament
I’m embarking on a insect-weight combat robot build (generally <1.5kg total weight). I’ll probably start with a 150g fairyweight (antweight in the UK). At this size, bots are usually 3D printed with very little, if any, metal armor. Carbon fiber filled nylon is usually used by serious builders, but I need a filament that is easy to print on the stock Mini. Any recommendations? I’m thinking about carbon fiber PETG, but which brand? I’ve also seen other fibers used - Kevlar, fiberglass, steel, etc.
Ultimately, I want the toughest print I can get from a stock Mini (just a hardened nozzle upgrade).
RE: Need recommendation for easy-to-print engineering filament
I'll try to answer my own question since I haven't received any replies and others may be interested in knowing the answer.
After a couple of days of research, I've determined that carbon fiber filament is not needed for my purposes. CF improves stiffness, but often degrades other qualities of the filament, such as tensile strength. I know, this sounds counter-intuitive, but it is true for filament with very short CF strands. Most CF filament is about 20% CF and 80% polymer. The CF displaces the binder (polymer), so the extruded cross section has 20% less binding capacity than non-CF filament. This reduces tensile strength and this has been shown in tests from multiple sources.
For my application, I don't need stiffness as much as I need strength and toughness. Plain PETG is probably better than CF PETG for me. However, there is an even better option. I've ordered some Taulman Alloy 910 which is a nylon that is modified to print easier than normal nylon and combines the stiffness of PLA with the durability of nylon. It does not use any composite fibers like CF, so a hardened nozzle is not necessary.
I had previously ruled out any type of nylon because it is not a supported material for the Prusa Mini. However, I've learned that it prints well on the Mini and a number of people have posted success stories. I suspect it is not listed as a supported material because of first layer adhesion problems on the stock Prusa build plates. However, with a bit of care, it seems to be possible. Here's a thread with a discussion of printing nylon on the Mini.
RE: Need recommendation for easy-to-print engineering filament
It depends what you need to defend against. For impact resilience don't ignore flex filaments. For mechanical cutters consider gluing a Kevlar cloth cover on the outside - it will be ripped off but is then very likely to clog the opponent's saw.
1.5kg sounds like a very big insect. Even my largest robots are smaller; 'though they are not intended for combat.
Cheerio,