What would be a good filament for building strong “non flex (speak stiff as possible)” parts? I am looking for a filament to print actual tools and they should be as rigid/stiff as possible.
But I also want it to print without much hassle, without enclosure and without high-temps, so no nylon and PC for example. Can you recommend filaments for my described scenario?
I already checked Tom’s #Filaween wall of data, but it is clear that there are many filaments missing.
Would ASA or carbon fiber filled filament be something I am looking for?
You are looking or ColorFabb PA-CF. Prints very easy without warping at 50°C on G11 (similar to FR4). PA-CF is stiff as hell.
@Niko1 I‘ll take a look at PA-CF.
@Alex_Skoruppa Maybe worth a try, thx for this tipp. I know you did print CF and ASA parts, what is your opinion on them?
Wouldn’t nylon be good for this?
Carbon fiber fill is… it’s cool, but it’s only as tough as whatever it’s filled into. The CF adds some small amount of strength, but I think people are mislead about “fill” filaments to a degree.
Anyone has experience with POM/Acetal? Google says it may be good, too.
Commenting to subscribe because it’s clear those commenting have much more experience in this area and I’d like to learn more.
Ditto Adam.
@Rene_Jurack POM typically has four times the shrinkage of ABS. It’s available as a filament but I question its printability. It’s something I plan to try with an exotic DIY machine but otherwise it’s probably best to avoid.
What kinds of tools?
Without considering composites or annealing type effects, all filaments have to obey the iron triangle of FFF:
Stiffness + Temp Resistance = Warping.
ABS and PC warp because they’re stiff and have high glass points. PLA is stiff and low-warp because it has a very low glass point. PETG is moderately low-warp because it has a moderate glass point and a moderate stiffness.
Big exceptions:
- Highly crystalline plastics like virgin nylon and POM will warp drastically more than amorphous plastics like PLA or PETG, for comparable Tg and stiffness. Crystallinity is good for most mechanical properties but awful for FFF bed adhesion. All mainstream filament blends are low-crystallinity polymers. (PLA is an oddball because it can be printed amorphous for low warp and then some blends can be annealed crystalline for better performance.)
- Composite fiber fillers with low coefficient of thermal expansion like fiberglass and carbon fiber will greatly reduce warping AND increase stiffness in any plastic. This is the best way to break the temp-stiffness-warping relationship. Adding composite fiber to a high-warp, high-toughness material like nylon or POM or PP is super advantageous… IF the plastic sticks to the fiber properly. For example, composite PLA is stupid because PLA doesn’t stick well to the fibers, and it’s generally pretty dumb to pair a stiff, brittle plastic with a stiff filler… you get a brittle and weak composite. (CF-PLA is super stiff but tends to be no stronger than virgin PLA.)
For max stiffness, I strongly recommend a composite filament, but make sure you get a premium mechanical application version like 3dxtech sells rather than “look how cool carbon fiber is” hobbyist nonsense.
Want to see where this conversation ends up. For a possible comparison test PLA that has been annealed (baked and then dipped in boiling water) is nearly as strong as ABS from some of the tests I’ve read. It will shrink during the process but is much less prone to warping from what I understand.
I haven’t seen PETG mentioned, so that’s something Id look at. But you may need to look at printing molds and casting it. Look at smooth-on for their resins.
PETG is not stiff.
Oh, aside from CFR- or GFR-filaments, you may also want to consider designing parts to be reinforced with selective bits of metal. For example, it’s usually trivial to boolean a hole out of the part for a long bolt or threaded rod that clamps the part together. You can reinforce selectively this way, like along a long handle or to reinforce Z layers against delaminating. Adding a few M5 bolts in smart places will add a more strength and stiffness than any filament selection…
Oh, one more comment… CF filaments might not be a good choice for hand tools due to the possibility of getting surface fibers into people’s hands as skin irritants. I haven’t seen any research or anecdote on this yet, but I’d be hesitant to try it myself.
Today I had to realise that PA-CF becomes soft after a few days. I think it is a moisture Problem. F**K!
@Niko1 Can you elaborate?
Perhaps next weekend.
Water is a plasticizer for nylons, but the CF should keep it fairly stiff and stable… at least compared to virgin PA…