<p>Calculations such as you want are not possible in my opinion except in such general terms as to be useless. Differences in layer height, layer adhesion, print quality and what heat you printed the item would all affect the physical properties.</p>
<p>Since it's not a manufactured item with known properties but a unique one. You would have to print and test it yourself.</p>

CC BY-SA 4.0
2022-10-07T10:45:10.103Z
2022-10-07T10:45:10.103Z
Kilisi
<p>Here are some general issues with load bearing 3d prints for this type of usage:</p>
<ul>
<li>If this is to be used outside, plastic has issues with both water and UV exposure making it brittle.  PETG does better on both of these areas than either PLA or ABS.</li>
<li>Plastic generally does better with compression than with shear or pulling.  In other words, hanging something from plastic might not work well but it might work as a bottom support or in a situation where it is squeezed rather than pulled.</li>
<li>Even if the plastic appears strong enough initially, it may &quot;creep&quot; where the plastic deforms under stress over time.  This applies to all three of compression, shear, and pulling.</li>
<li>To optimize for strength, print direction is critical.  You want to make sure that the stress will not be trying to shear print layers.  Also (for any material, not just 3d printed plastic), curved shapes are stronger than square corners.  A fillet instead of a corner makes a big difference, but more extreme curves are even better.</li>
<li>If you are going to make this out of modular pieces joined with a second material, it is very hard to characterize the strength of the resulting composite, but generally it is stronger than using a single material.</li>
</ul>

CC BY-SA 4.0
2022-10-08T15:32:08.570Z
Regarding creep, it's very material dependent whether and to what degree it happens. The general consensus is that PLA and nylon do creep, ABS, ASA, and PET don't, and PETG probably does.
R.. GitHub STOP HELPING ICE
CC BY-SA 4.0
2022-10-08T15:38:19.963Z
ABS does creep, but not a lot, and not nearly as much as PLA.  ABS is fairly elastic, tending to return to its previous shape when stress is removed, but it can be made to creep.  PLA tends to conform to the shape the stress puts on it, even when it is very small and brief.
user10489
CC BY-SA 4.0
2022-10-08T14:12:52.783Z
2022-10-08T14:12:52.783Z
user10489
<p>You could print a decorative layer that attaches to the WPC board.</p>
<p>It would be faster and cheaper, and there'd be no doubt about its strength.</p>

CC BY-SA 4.0
2022-10-08T11:05:24.423Z
i was beginning to lean in this direction too: it would save tons in filament cost since strength would no longer be required
velis
CC BY-SA 4.0
2022-10-08T13:59:06.647Z
It's far too easy to fall to the [Law of the instrument](https://en.wikipedia.org/wiki/Law_of_the_instrument). To a man with a hammer, every problem looks like a nail.
Ray Butterworth
CC BY-SA 4.0
2022-10-07T13:55:45.790Z
2022-10-07T13:55:45.790Z
Ray Butterworth
<p>I need to build me a small support wall 250x80 cm mounted on two metal supports approximately 200 cm apart.</p>
<p>I was looking into WPC (Wood Plastic Composite) boards and then it hit me that I may be able to make it functional AND pretty with my 3D printer (Prusa MK3S + MMU2).</p>
<p>However, I have zero idea on how to calculate whether the board will be able to handle the weight of the soil I would shovel behind it, if at all.</p>
<p>My current design proposal is to make a hexagon mesh of PETG filament. The hexagons would have cylinder cutouts in all three directions, through which I would then hammer in cylinders to bind them together. Perhaps even some edge contours so that they fit perfectly.</p>
<p>But, my problem is that I don't know how to calculate the strength of such a solution (or any other).</p>
<p>Is this even a viable idea?</p>
<p>The filament type needs a bit more explanation:
My current proposal is PETG since I read that PLA will become brittle with time (as I can attest to myself having to replace my flag pole holder every 3 - 4 years)</p>
<p>I don't want ABS since I have horrible experience printing it.</p>
<p>I did not find anything of particular use when searching for &quot;3D print load-bearing&quot; on this site and similar with Google searches...</p>

CC BY-SA 4.0
2022-10-07T11:50:56.563Z
The answer is: "Yes you can", but at what design... (not as compact as WPC boards). Maybe you should add an image of the geometry or a sketch. I can't see you print lengths of 80 cm. Furthermore, it might become pretty impractical to print considering the multiple parts and it may not be cheap.
0scar
CC BY-SA 4.0
2022-10-07T17:45:09.797Z
People make load-bearing parts for printers that handle kg-scale moving parts accelerating at 3-5 gs out of ABS, ASA, PC, and PET, so in general yes, but it depends on the specifics of your load.
R.. GitHub STOP HELPING ICE
CC BY-SA 4.0
2022-10-07T18:10:08.470Z
Even if your design ends up being strong enough, consider the time and cost of printing it vs simply buying some WPC and installing it. Unless you're in it for the "Look what I did, it's so cool!" factor, it seems totally impractical and overly expensive to me...
FreeMan
CC BY-SA 4.0
2022-10-07T19:47:20.797Z
They've 3D printed entire bridges (I think just for pedestrians so far, not sure if there are any vehicle-rated bridges yet).  So it's possible, just not likely to be within an amateur budget....
Darrel Hoffman
CC BY-SA 4.0
2022-10-07T21:54:34.147Z
Yes, of course, in your wording. Hasn't YouTube showed you 37-or more examples?
Robbie Goodwin
<print-strength>
Can I 3D print a wall assembly and expect it to be load-bearing?
velis
# Can I 3D print a wall assembly and expect it to be load-bearing?

(Asked by: username_0 on 2022-10-07)

I need to build me a small support wall 250x80 cm mounted on two metal supports approximately 200 cm apart.

I was looking into WPC (Wood Plastic Composite) boards and then it hit me that I may be able to make it functional AND pretty with my 3D printer (Prusa MK3S + MMU2).

However, I have zero idea on how to calculate whether the board will be able to handle the weight of the soil I would shovel behind it, if at all.

My current design proposal is to make a hexagon mesh of PETG filament. The hexagons would have cylinder cutouts in all three directions, through which I would then hammer in cylinders to bind them together. Perhaps even some edge contours so that they fit perfectly.

But, my problem is that I don't know how to calculate the strength of such a solution (or any other).

Is this even a viable idea?

The filament type needs a bit more explanation:
My current proposal is PETG since I read that PLA will become brittle with time (as I can attest to myself having to replace my flag pole holder every 3 - 4 years)

I don't want ABS since I have horrible experience printing it.

I did not find anything of particular use when searching for "3D print load-bearing" on this site and similar with Google searches...

**Tags:** print-strength
> **Comments:**
> **username_1**: The answer is: "Yes you can", but at what design... (not as compact as WPC boards). Maybe you should add an image of the geometry or a sketch. I can't see you print lengths of 80 cm. Furthermore, it might become pretty impractical to print considering the multiple parts and it may not be cheap.  
> **username_2**: People make load-bearing parts for printers that handle kg-scale moving parts accelerating at 3-5 gs out of ABS, ASA, PC, and PET, so in general yes, but it depends on the specifics of your load.  
> **username_3**: Even if your design ends up being strong enough, consider the time and cost of printing it vs simply buying some WPC and installing it. Unless you're in it for the "Look what I did, it's so cool!" factor, it seems totally impractical and overly expensive to me...  
> **username_4**: They've 3D printed entire bridges (I think just for pedestrians so far, not sure if there are any vehicle-rated bridges yet).  So it's possible, just not likely to be within an amateur budget....  
> **username_5**: Yes, of course, in your wording. Hasn't YouTube showed you 37-or more examples?  

---

## 3 answers

### Answer by username_8 on 2022-10-07. Score: 8 | Accepted answer

You could print a decorative layer that attaches to the WPC board.

It would be faster and cheaper, and there'd be no doubt about its strength.

> **Comments:**
> **username_0**: i was beginning to lean in this direction too: it would save tons in filament cost since strength would no longer be required  
> **username_8**: It's far too easy to fall to the [Law of the instrument](https://en.wikipedia.org/wiki/Law_of_the_instrument). To a man with a hammer, every problem looks like a nail.  

---

### Answer by username_6 on 2022-10-07. Score: 4

Calculations such as you want are not possible in my opinion except in such general terms as to be useless. Differences in layer height, layer adhesion, print quality and what heat you printed the item would all affect the physical properties.

Since it's not a manufactured item with known properties but a unique one. You would have to print and test it yourself.


---

### Answer by username_7 on 2022-10-08. Score: 1

Here are some general issues with load bearing 3d prints for this type of usage:

* If this is to be used outside, plastic has issues with both water and UV exposure making it brittle. PETG does better on both of these areas than either PLA or ABS.
* Plastic generally does better with compression than with shear or pulling. In other words, hanging something from plastic might not work well but it might work as a bottom support or in a situation where it is squeezed rather than pulled.
* Even if the plastic appears strong enough initially, it may "creep" where the plastic deforms under stress over time. This applies to all three of compression, shear, and pulling.
* To optimize for strength, print direction is critical. You want to make sure that the stress will not be trying to shear print layers. Also (for any material, not just 3d printed plastic), curved shapes are stronger than square corners. A fillet instead of a corner makes a big difference, but more extreme curves are even better.
* If you are going to make this out of modular pieces joined with a second material, it is very hard to characterize the strength of the resulting composite, but generally it is stronger than using a single material.

> **Comments:**
> **username_2**: Regarding creep, it's very material dependent whether and to what degree it happens. The general consensus is that PLA and nylon do creep, ABS, ASA, and PET don't, and PETG probably does.  
> **username_7**: ABS does creep, but not a lot, and not nearly as much as PLA.  ABS is fairly elastic, tending to return to its previous shape when stress is removed, but it can be made to creep.  PLA tends to conform to the shape the stress puts on it, even when it is very small and brief.  

---

