Strongest possible print settings

[RobSly 0]

This part is 3 mm thick/2 mm thick bottom. I am looking for the perfect Curasettings for my ender 3 v2 with petg to make this model as strong ass possible. Its not important that it has to be supernice, it has to be strong! Especially the bridge!

Should I print with no walls and a strong infill pattern? I really hope someone could give me some hints or maby have a profil I can use for cura 🙂

[Smithy 1,041]

Strong can be everything, but I think your part should be as stiff as possible?

PETG is for that case not the best choice, but depending what you mean with strong/stiff I think it should also work with PETG when you want to mount a Go Pro.

 

I would use enough bottom and top layers that you have no infill at all, for 2mm it really doesn't matter. 

[RobSly 0]

Hi, thanks for your reply. It is important that the bridge is strong and can withstand as much forces as possible. The hole under the bridge is for a velcro strap. I use petg because it is going to be used outside in the sun and also for the strenght. 

Edited December 31, 2021 by RobSly

[geert_2 533]

It also depends on how flexible it has to be, thus how resistant to warping?

 

When I print carabiner hooks in PLA, they are much harder than in PET. However, I need to bend the carabiners to make them hook around stuff, and then the PLA carabiners break sooner than the PET.  PET is a bit more flexible, so it can withstand more warping. But after a year or so, they also tend to fail.

 

PLA generally cracks before it fails. My PET generally snaps all of a sudden without warning. Could be different for different brands.

 

Also, PLA can be glued easily with cyano-acrylate glue, after roughening its surface with sandpaper or a file. PET is much harder to glue.

 

If it has to sit in the sun outdoors, laying around on sand or stones, PLA is going to warp for sure. You would need a high-temp version PLA (+60-70°C). PET can withstand the sun, at least here in Belgium, Europe, in our moderate climate. I don't know about deserts.

 

If it has to snap-lock around things, a PLA lock will initially snap much harder. But due to creep deformation, it may loose its clamping force. And it may become more brittle and break after a year or so.

 

For printing, I would recommend printing very slow, so the new melt has time to warm-up the previous layer and bond well, and the extruded saugages have time to spread into all corners. Also print in thin layers, that gives less indents, less layer lines. But printing slow makes the filament sit in the nozzle for a very long time, so reduce temperature to the absolute minimum of the range of that material, or even slightly below the range. So it does not decompose in the nozzle, nor clog it. I would print at 100% infill, and a couple of outer lines (e.g. 2x or 3x nozzle width), to give the best interconnection and least amount of internal gaps that could cause stress. But some people say that a bit less infill would give more flexibility and more ability to absorb shocks. I don't know. So, that might be worth comparing too?

 

Make a small test model, and do the comparative tests on it.

 

In general, if it was for myself, I think I would rather go for PET. My PET-prints do survive in the car, PLA-prints don't. If not strong enough, then I just make them thicker...

 

If you have nylon or polycarbonate, or maybe PU, they could be way stronger and/or more resistant to breaking, but I have no experience with printing these. Seems to be more difficult.

 

 

Carabiner hooks: left in PLA (cream), right in PET (green)

 

Note the cracks and permanent deformation in the PLA parts, they are close to failure:

 

The model in CAD:

 

The fracture-surface of a PET one. Notice how the fracture-lines go diagonally through all layer-lines, they don't follow the layers, or not too much. You can see the primary and secondary starting points, the centers of the star-patterns. This one snapped very suddenly, without prior cracks or warning, typical for this PET: