[watertight underwater container able to withstand high pressure]

On 1/25/2021 at 4:02 PM, geert_2 said:

When making tiny filters for a vacuum pump, I had to print them very slowly and in very thin layers. Otherwise, if printed at 0.2 or 0.3mm layers, it had lots of tiny openings, through which tiny jets of water squirted out, similar to out of an injection needle. When printing at 0.06mm layers and 25mm/s in PLA, it was water-tight.

 

But if you are going to print your huge model at such a low speed and layer height, it is going to take forever.

 

So, I would make a *small* test model first, and see how that works under high pressure. Put tap water on it, or even via a high-pressure cleaner, and see how that works out (Use safety glasses and equipment!!!). If it is water-tight and can withstand high pressure from inside-out, which is the weakest, then it will also withstand high external pressure.

 

If you would use paint, try to find one that bonds very well chemically, so it does not delaminate.

 

The filters I printed: the bottom was printed with 70% infill if I remember well, to get the tiny holes for the filtering-effect, good enough for this purpose. Then both halves were glued together around the edges.

 

 

 

Thanks! This is very insightful. I am quite new to 3D printing. If I understood correctly, first of all I need to use a very thin extruder, like 0.06mm. Then I need to 3D print with high density. Considering the size of the item is roughly 10 cm diameter x 30 cm height, how long would it take?

[watertight underwater container able to withstand high pressure]

23 hours ago, svandestaak said:

Hi Maurosacchi. Personally, I would be looking at PP with glass/carbon fiber. Extremely strong and PP works well with liquids. Make sure when you print that the z seam alignment is at random. And I would also print it with 100% infill. Final version anyway.

 

If you do want to go for PP, make sure you use the adhesionsheet and/or pp-adhesion from Magigoo. Those are the only adhesion solutions which worked for me when I used PP with GF (30%): XSTRAND™ GF30-PP (Polypropylene + Glass Fiber) (crea3d.com)

 

Sounds like a very interesting project, SandervG forwarded this thread to me. 🙂

 

Thanks! Any specific extruder diameter to be used with this filament?

[watertight underwater container able to withstand high pressure]

On 1/20/2021 at 4:43 PM, GregValiant said:

These are just some random thoughts...

 

The typical printing materials are fond of water.  I'm guessing that would be a downside so if you can get something with a low affinity for water, that would be a prime consideration.  It may be why Delrin was picked over something like Nylon.  A prototype for initial pressure testing could be made from something cheaper(?)

 

Among other things, "Layer Adhesion" will play a part in water-tightness.  Maybe a coating over the print?

 

Thanks for the suggestions. What coating do you have in mind? Epoxy? Is there a specific product and if yes, what filament should I use with it to achieve the end result I am looking for?

 

On 1/20/2021 at 4:43 PM, GregValiant said:

I would make the bottom of the vessel a dome.  The print will be weaker than any traditional solid part.  A domed bottom would enhance it's strength in at least that area.  Taking that further, I'd think about an ovoid as well.  Egg shapes bear up well to uniform external pressure.  The inside could still be cylindrical.

 

Put the battery in and fill it with dielectric oil?  I think any infilled volume would still end up near 100% infill.

 

 

 

Unfortunately I cannot make the whole surface oval. I could make the bottom round though. It would not be possible to use it. This canister is placed on the waste belt of a diver, It would become too inconvenient with that shape.

[watertight underwater container able to withstand high pressure]

I am trying to 3D print a diving canister used to store battery packs that power underwater torches, heating elements, etc. Traditionally these canisters are machined with a lathe using Delrin acetal homopolymer (Polyoxymethylene POM). They are often rated to 200 or even 300 meters (600-900 feet), which means 21 to 31 bars of atmospheric pressure (300-450 psi).

 

This is how a Delrin machined canister would look like:

 

 

And this is one of the 3D model to be used for 3D printing:

 

 

I know POM-C is available from FrontierFila and Uayella as filament for my S5 Ultimaker. Nevertheless I have several questions before commencing this work:
 

1. although POM-C is the preferred material when this item is machined, would it be the preferred solution for 3D printing?
2. once the material is selected, how do I calculate the necessary thickness to withstand the indicated pressure?
3. how do I secure the final result would be watertight?
4. what settings should I use in Cura to execute the printing?

 

It would be great if someone with more experience would guide me through this project! Thanks in advance!