Best Filament for Long-term Submerged Prints
 

Best Filament for Long-term Submerged Prints  

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rocheros
(@rocheros)
Active Member

I'm designing a product for underwater use in freshwater ponds. It will be submerged for for months, possibly years, at a time. 

Assume that PETG is the way to go.

My only concern is that PETG is quite flexible. For this use case, however, a more rigid material is preferable. It's not required, as I can add stainless steel supports if necessary. But, I'm hoping to avoid that if I can. 

Would appreciate any suggestions from you experts.

Thanks!

 

 

Posted : 22/02/2021 1:57 am
John Doe
(@john-doe-3)
Trusted Member

I would more concentrate on surface area of the object. Like some special for-deep-waters  paint or something like that put on the object.

Posted : 22/02/2021 7:49 am
cwbullet
(@cwbullet)
Illustrious Member
Posted by: @rocheros

I'm designing a product for underwater use in freshwater ponds. It will be submerged for for months, possibly years, at a time. 

Assume that PETG is the way to go.

My only concern is that PETG is quite flexible. For this use case, however, a more rigid material is preferable. It's not required, as I can add stainless steel supports if necessary. But, I'm hoping to avoid that if I can. 

Would appreciate any suggestions from you experts.

Thanks!

 

 

I would go with PETG or PETG with CF.  The flexibility will not hurt anything as long as it is not going to 1000s of feet.  

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Chuck H
3D Printer Review Blog...
Posted : 22/02/2021 10:57 am
rocheros liked
towlerg
(@towlerg)
Prominent Member

It's amazing how a few ribs can can make a part significantly more rigid. Some CAD packages have optimisation routines.

Posted : 22/02/2021 11:05 am
rocheros liked
towlerg
(@towlerg)
Prominent Member

I would have thought nylon but I have no evidence to support that.

Posted : 22/02/2021 11:06 am
cwbullet
(@cwbullet)
Illustrious Member

@towlerg

Nylon or nylon X would be good choices also.  A ltitle more challenging to print but they would work.  

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Chuck H
3D Printer Review Blog...
Posted : 22/02/2021 11:11 am
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Diem
 Diem
(@diem)
Reputable Member
Posted by: @rocheros

I'm designing a product for underwater use in freshwater ponds. It will be submerged for for months, possibly years, at a time. 

At pond-bottom temperatures you might as well use PLA.  At the surface, especially in very shallow, sun warmed water it is not suitable for more than six months or so.

PLA is significantly damaged by solar ultraviolet.  Ultraviolet is filtered out by a few inches of water.

PLA is technically biodegradable: at hot composting temperatures it decomposes in a couple of years.  In cool soil or cold water it lasts for tens of years, OK, eventually it degrades so you are not adding much to the long term plastic burden of the planet but for ordinary purposes it's just another plastic with a decent working life.

Cheerio,

Posted : 22/02/2021 2:46 pm
cwbullet
(@cwbullet)
Illustrious Member

@diem

Not sure how biodegradible it is.  That is another experiment.  

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Chuck H
3D Printer Review Blog...
Posted : 22/02/2021 3:40 pm
Dan Rogers
(@dan-rogers)
Reputable Member

I use both PLA and PETG for fishing lures that I send down to 100 to 150 feet of water.  At depth, the parts all will become infused with water in the internal channels - and even if you go 100% solid fill, water pressure will find a way.  Now, a koi pond is not a high pressure situation, so you will probably do better.  I now make it a practice to a) turn off G code for linear advance (helps with seepage) and then I use spray acrylic after the print to seal the part.  This has made a big difference in the "waterproof-ness" of my lures.

Posted : 22/02/2021 4:07 pm
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mrstoned
(@mrstoned)
Estimable Member

For the planters i make, i usually go with PLA, around 3 walls of atleast 0.8mm wide external perimuter extrusions.

I then use a sprayprimer on the inside (multiple thin layers).

 

Design for submerged is different i the way you have omni-directional force all around, as opposed to gravity and wicked effect in planters.

Also depending on the tupe of pond, leakage from the plastic might be a concern. I would choose a food-grade filament just to be safe.

Now i'm guessing, but PETg is more resiliant to "outer wear" then PLA  as it stretches instead of scrapes.

 

If structural stiffness is needed, a simple exterior bracket-clamp might be all that's needed.

 

Of course, it also all depends of what the design is to be used for.

Might be easier to design it to allow for it to be waterlogged and schedule for replacing inplace of more expensive "beefing up". Improving the design in the process.

Flsun QQ-s "pro". Tevo Nereus. Prusa Mini+ KIT on order....
Posted : 22/02/2021 5:15 pm
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rocheros
(@rocheros)
Active Member

Really appreciate the recommendations!

One thing I should have mentioned: the parts themselves need not be watertight. They're strictly structural and won't contain anything that needs to be protected from water. Water in the voids shouldn't be an issue. In fact, it would actually help as the device needs to be negatively buoyant (it sits on the bottom).

I simply need the material itself to withstand long-term water exposure, the printed layers to not delaminate over time, and as I said earlier, would be good if it could be more rigid than standard PETG.

Ordered some nylon and nylon fortified with carbon fiber today. Already have some PETG with CF. Just need to a new nozzle to print it. Ordered that, too!

 

Posted : 23/02/2021 1:11 am
Diem
 Diem
(@diem)
Reputable Member

One thing I should have mentioned: the parts themselves need not be watertight. They're strictly structural and won't contain anything that needs to be protected from water. Water in the voids shouldn't be an issue. In fact, it would actually help as the device needs to be negatively buoyant (it sits on the bottom).

Choose one of the fills that allow all the voids to be connected and use a couple of strategically placed modifiers with zero perimeters to allow water to enter freely.

I simply need the material itself to withstand long-term water exposure, the printed layers to not delaminate over time, and as I said earlier, would be good if it could be more rigid than standard PETG.

I really do suggest you print a couple of PLA test parts and sink them where you can check on them over time - you might be surprised at the result.

Cheerio,

 

 

Posted : 23/02/2021 2:45 am
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Dragon1291
(@dragon1291)
Trusted Member

I would advise against Nylon unless you are 100% sure the blend you are going with is ok with long term water exposure. At my old job we had  nylon clips that shattered in a high humidity environment. 

Posted : 23/02/2021 6:33 pm
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rocheros
(@rocheros)
Active Member

@dragon1291

Yes, this is what I am finding out as well. Just doesn't hold up in submerged situations. 

Last night I found a YouTube video from a company called VisionMiner discussing the pros and cons of Nylon with CF.  The link is cued to the spot where he talks about how Nylon can degrade during long-term water submersion.

Posted : 23/02/2021 7:55 pm
Photogad
(@photogad)
Eminent Member

Just don't use cubic infill, it will make the object float to the surface

Posted : 26/02/2021 12:05 am
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