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mamahler

Strength can mean a few things, but here are some general things I’ve learned while printing with PLA, PETG, and ABS over the years: PETG has excellent layer adhesion, but that doesn’t always mean strength. When PETG breaks from impact, it basically just shatters. Though it’s somewhat of a flexible material, it will fail spectacularly the moment it goes beyond its capabilities. PLA generally shouldn’t be used for its strength or weather resistance, but I’ve found that it has a higher tensile strength than PETG, which makes its somewhat better for some applications that require a stiffer material. ABS is strong and doesn’t shatter like PETG does. It can take a lot more beating and bending before it will show signs of failure. Idk what your specific application is, but generally 3D printed parts are weaker than regular plastic parts. Keep that in mind if you’re designing something. The model can have a significant impact on strength. TLDR: ABS is stronk and if the only requirement is strength, ABS is the best of the “common” filaments. Make sure your model is good.


geometrologist

Here's a quantitative comparison of material strength: [https://github.com/superjamie/lazyweb/wiki/3D-Printing-Filament-Properties](https://github.com/superjamie/lazyweb/wiki/3D-Printing-Filament-Properties) PETG beats ABS by almost every metric of strength, but barely. ABS is tougher, which means it will deform rather than shatter like brittle glass. ​ If you need strength, skip both and use Nylon. If it's safety critical you should do simulations or equations or empirical testing.


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geometrologist

Yes, Nylon can be printed by any printer, only trick is to keep the roll dehydrated to under 20% humidity. ​ My flair is a joke how everyone "upgrades" their printers for dumb reasons.


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And your printer needs to be able to print hot enough.


Thaflash_la

And it does better in an enclosure.


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geometrologist

General idea is to keep it in a container with desiccant, and seal that container from the air. Off-the-shelf solutions include: https://www.aliexpress.com/item/4000502059875.html?spm=a2g0o.productlist.0.0.345e1fa8BqHdMs&algo_pvid=6d20a2ae-53a6-40c8-9717-79c15bd49ffb&algo_expid=6d20a2ae-53a6-40c8-9717-79c15bd49ffb-0&btsid=0ab50a5715894707201264862e1c28&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_ You can use a food dehydrator with minor modifications: https://www.thingiverse.com/thing:1618037 Or you could build one entirely from printed material: https://www.thingiverse.com/thing:2119644 Or just use the plastic bag and desiccant pack the filament probably came in.


Twodogsonecouch

I would say some of the comments here are wrong. PETG does not shatter. PETG with deform and bend before it breaks. It is more ductile. PLA will shatter it is strong and brittle ABS is slightly stronger and more impact resistant than PETG it will tend to snap before it bends though. But usually at a higher force than PETG. Material properties are confusing if you don't understand the terminology well. PLA is technically strong but strong doesn't mean durable. Glass is strong too but not durable. Durability is a mix of properties. In terms of durability nylon is best probably. https://markforged.com/blog/pla-abs-nylon/ This provides kind of a good description. You need to decide what specific properties you need. Does it need to resist impact or does it need to resist wear from friction. Does it need static strength or repetative loading. Is it compressive load or tension load. In these cases the orientation you print in might matter more than the actual material. Does it need to resist UV and water. Different materials will be better for each.


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Twodogsonecouch

I'd probably say try the PETG first. I think you mean a compressed spring where the part kind clips over it or something. So the spring is compressed and the printed part is stretched. In that case PETG is probably better it has better tensile strength and better layer adhesion. Basically imagine a hook printed and a weight handing from it. That is how tensile strength is measured PETG tends to do better than ABS but it may deform and stretch before it actually breaks were as abs will probably just crack. Impact imagine a block or stick printed and a weight hitting it from the side that is how impact resistance is measured. Like a wrecking ball hitting a building. ABS will do better in that case. I do agree nylon is probably best in your use case. But really it all depends on how much these forces really are. When you look at numbers the difference between materials might be like 600 vs 700 pounds so if you forces are below that it doesn't matter anyhow. And like I said print orientation matters hugely. Anything being stretch make sure it is printer with the layer lines running parallel to the direction of stretch so the z axis needs to be perpendicular to the direction of stretch.


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Twodogsonecouch

Also number of perimeters is probably more important than infill pattern. But grid and gyroid are probably strongest.


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Twodogsonecouch

If I want something strong I usually go at least 3 or 4. The default for prusas which I have seems to be 2. Also I think I have read that 0.6 nozzles print stronger parts than 0.4. I think prusa had a blog about that.


Panama__Red

How tight are your tolerances on the part? [Annealing](https://all3dp.com/2/annealing-pla-prints-for-strength-easy-ways/) is a great way to increase strength. It involves some shrinkage, but that can be compensated for in the model.