LW-PLA for buoyancy?

[kammel78]

You absolutely can do single wall prints. Vase mode in Prusaslicer is a great example.

2-3 walls is the default setting for a 0.4 nozzle on various slicers, resulting in a wall thickness of about 1.2mm(depending on layer height setting). Personally, I am a 10 wall guy resulting in 4-4.5mm thick walls for everything I make no matter what my infill setting is. For floats or anything that needs reduced water intrusion that would affect buoyancy, 10 walls is the way to go.

I wasn't generalizing PLA at all. I am referring to the LW-PLA the OP is inquiring about to make buoyant components and floats. LW-PLA is a Specialty PLA formulated, that when extruded, it increases its volume about 3 times reducing its weight 50% by the varied density. For instance, to get a 0.4 wall thickness with LW-PLA, you have to adjust flow down to 50% or less and vary the nozzle temp. At normal flow at a higher temp your wall can end up 1mm to 1.2mm with a single wall count. LW-PLA is a specialty filament that takes a bit of fiddling with design and settings to get right. LW-PLA's intended use is for thin, lightweight, single wall parts for model planes, car bodies and cosplay costume pieces. the parts are are not structurally sound and will only take light loads and stress. So you might get a light part, but it wont withstand any water pressure at depth. Regular PLA is a much better choice.

As I stated earlier in my original statement that "this filament would give no benefit". What I thought was implied was "LW-PLA offers no benefit over regular PLA or any other filament of choice". Hope that clears things up for everyone.

The LW-PLA is really cool stuff. Check out YouTube for instructional videos on settings, design and what people are making with this filament.

I see the confusion. My first post was a response to the guy talking about PLA and when you replied I assumed you were talking about PLA as well, NOT LW-PLA. Makes much more sense...I was genuinely confused why anyone would be saying you should only print PLA single wall.

FWIW, I designed a BOV chin rest specifically to counter the extra weight of the BOV and was able to get the total negative buoyancy equal to a standard DSV. However, my assumption is that at depth (4ata) water ingress will negate any positive buoyancy at 1ata. Haven't tested at depth yet. Printing it watertight would obviously be counterproductive. Could try epoxying the print too, maybe.

I've been trying to source the same material used for uwp floats but it seems like maybe a specialty material.

 

[ScubaToneDog]

I've had really good results with PLA Gloop for gluing and sealing printed parts. It is specially made just for PLA. Worth a try. Its easier than fooling around with epoxy and warping your parts as it cures (had that happen once). I have heard that 2 light coats of spray Polyurethane works, but have never tried it.

As for your floats, the ones I've seen are made with EVA foam or a carbon fiber tube . The foam and carbon fiber tubing can be bought on amazon. The foam is high density and chemical resistant so should stand up pretty well. You could make your own tubes with sheets and resin on Amazon as well. Tough part is making the jig for the tube and not getting resin everywhere...lol. My brother used to make his own custom fly rods with carbon fiber. I have never had patience or artistic skill to make anything like that.

I'm sure you will figure something out.

 

[kammel78]

I've had really good results with PLA Gloop for gluing and sealing printed parts. It is specially made just for PLA. Worth a try. Its easier than fooling around with epoxy and warping your parts as it cures (had that happen once). I have heard that 2 light coats of spray Polyurethane works, but have never tried it.

As for your floats, the ones I've seen are made with EVA foam or a carbon fiber tube . The foam and carbon fiber tubing can be bought on amazon. The foam is high density and chemical resistant so should stand up pretty well. You could make your own tubes with sheets and resin on Amazon as well. Tough part is making the jig for the tube and not getting resin everywhere...lol. My brother used to make his own custom fly rods with carbon fiber. I have never had patience or artistic skill to make anything like that.

I'm sure you will figure something out.

I don't think it's EVA, EVA compresses too much. This stuff is much harder. Backscatter Underwater Photography & Video General Plastics (among others) are making proprietary foams for stuff like ROVs and other industrial marine applications. I'll probably start a new thread and stop hijacking OPs thread.

 

[ChrisMBC]

No, this is all really interesting stuff! I’m well aware of the existing foam options - my desire to print stuff is because I want to make more complex shapes than just a tube, and 3D printing is a lot easier than the subtractive processes.

I’m very curious about that PLA Gloop - I might look into the ABS version and have a go making some watertight structural floats

 

[kammel78]

FWIW, Overture and Polymaker both have pre-foamed LW PLA that doesn't require much more than tweaking retraction settings that may be worth giving a shot.

@ChrisMBC if you have a design, I'd be happy to help test, both different filaments and in water. I have very similar use case.

 

[ChrisMBC]

Bumping this slightly dormant thread to share: I bought some of Bambulab's new ASA Aero filament, and ran my first underwater test with it last night. Initial results were execellent: printed with 100% infill, there was no buoyancy shift from 0 to 30m, and the print weighed the same after the dive as before (i.e. no water absorbtion - not generally the case with a lot of my printed parts, even with 100% infill).

Hopefully the results stay consistent even deeper, but if so, it looks like we have a viable way to print buoyant material, which is excellent news for things like custom camera floats, or a neutrally-buoyant mount for a computer on a DPV (which was my first test print).

 

[kammel78]

Bumping this slightly dormant thread to share: I bought some of Bambulab's new ASA Aero filament, and ran my first underwater test with it last night. Initial results were execellent: printed with 100% infill, there was no buoyancy shift from 0 to 30m, and the print weighed the same after the dive as before (i.e. no water absorbtion - not generally the case with a lot of my printed parts, even with 100% infill).

Hopefully the results stay consistent even deeper, but if so, it looks like we have a viable way to print buoyant material, which is excellent news for things like custom camera floats, or a neutrally-buoyant mount for a computer on a DPV (which was my first test print).

Curious what the actual buoyancy was?

What's your thought process on printing 100% infill, to prevent water ingress?

 

[ChrisMBC]

Curious what the actual buoyancy was?

What's your thought process on printing 100% infill, to prevent water ingress?

The print came out to 0.6g/cm3; I think I can improve on that a little by tweaking the print settings as well

Idea with 100% infill is exactly preventing there from being any water ingress, which I've seen with all other prints that I've tried. It should also make the max depth more consistent - if I can work out the max pressure that the gas bubbles in the foam collapses, that would be the limiting factor.

 

[davehicks]

The print came out to 0.6g/cm3; I think I can improve on that a little by tweaking the print settings as well

Idea with 100% infill is exactly preventing there from being any water ingress, which I've seen with all other prints that I've tried. It should also make the max depth more consistent - if I can work out the max pressure that the gas bubbles in the foam collapses, that would be the limiting factor.

I printed and have been diving some Nauticam port floats that I made a few month back. I printed them with PLA+, and then coated with epoxy resin. I used 4 walls and 8% infill to keep the weight at a minimum. The custom fit design for the Nauticam Port 87 float collar I made is +355g or 12.5 ounces.

I also made some Floats that fit on a 12-inch ULCS strobe arms. I printed these in ABS and used acetone smoothing to make the parts watertight. It worked well for a couple of dives, but ultimately leaked. My design used a sandwich of the two parts with a channel for the ULCS arm. I think I used 8% infill with two internal ribs for 50% for structural support.

The weight/buoyancy advantage of this design over Jumbo STIX float cubes was marginal, so I didn't iterate on the design. If I decide to try this again, I will paint the parts with epoxy resin after the ABS smoothing.

Regarding this LW ASA filament, I would be interested in the weight buoyancy figures for something that approximates 4 jumbo stix floats. That would be 65mm square and 200mm long. Based on your .6g/cm3 figure, that would make your LW filament about 50% heavier than my ABS parts, which were about 200g.