3D Printed parts - Working at depth?

[saxman242]

Plus.. there's something to be said for just making things yourself. I'm not sure I can put it into words, but it definitely feels good.

There's also something to be said for knowing how to use the proper tool for the job. An fdm printer is not that in this case.


Now, if you wanted to use the fdm printer to print a master, pull a silicone mold off of it, and then cast a new plug out of a homogeneous material that was more appropriate for the application, you could get a part much better suited to the application and still enjoy the satisfaction of doing it yourself.

 

[seb13]

I'm not familiar with the mask or part, but do lots of 3d printing.

Some parts are used for 60psi+ CO^2 carbonation (using beer kegging fittings to carbonate beverages from used plastic coke bottles and the like). We make carb-o-ritas (carbonated margaritas ;-) and similar.

The quality of the material and the process of printing will have a significant impact on the finished product and it's properties. If this is just a 'plug' and not under pressure, it should be fine. If it is pressure bearing (to seal the area previously containing the communications gear, I personally would not do it.

The plug will not have to maintain high pressure as the interior of the mask will be at the same pressure as exterior. It just needs to prevent air from escaping. I am more concerned if micro bubbles are trapped inside the piece as they will be at surface pressure and will shrink at pressure, potentially separating the layers of the 3D printed part.

Pardon my ignorance, but why wouldn't you just contact the manufacturer of the mask and buy the proper plug? This seems like an awful lot of work for a part that you aren't even sure will work. It seems like failure of this part could potentially lead to a fairly sporty situation, so why take the chance?

OCEAN REEF Diving | Integrated Diving Mask

I tried and their customer service is nice and responsive, but I get something like "Yes, we sell the part, you have to call on the phone to order it", when I asked about the price, the answer was "Well, we don't have a catalog, just call us". I fell a little bit uncomfortable, ordering a part for which I don't know the price, nor the shipping cost and will have to give my credit card number to someone on the phone...
Anyway, in the end, I will try to get the part from my LDS but was surprise how easy it is to model and print a part that fits.

FDM parts are not air tight, even at 100% infill. I'd be less worried about microbubbles and more with interlaminary issues long term when under pressure. If you have the cad model and want a more reliable solution, I'd just send the model off to either be printed on an sla machine or machined out of delrin.

That's a good suggestion, I should try the professional printing online services and maybe print from nylon.

Plus.. there's something to be said for just making things yourself. I'm not sure I can put it into words, but it definitely feels good.

Yeahhhhh!

 

[saxman242]

maybe print from nylon.

An SLS part out of powdered nylon would be a much better choice than an fdm part. I have used BuildParts Home for sls nylon parts in the past and have always had amazing results. They are geared more towards professional clients though, so I can't speak to their pricing for a one or two off part.

 

[emoreira]

I've been 3D printing parts for scuba BCDs since several months. I print at 100 % infill with PETG and ABS. Those parts have been used in dives without any broken part. I've also printed with FLEX filament 2nd stage caps and a blind comms plug for an Ocean Reef Neptune Full Face mask with PLA.
All parts have done it's work without any problem. I do not print parts that hold pressure.
Many people said that I'm playing with "life support gear", however I print parts because that "life support gear" many times breaks like old paper.

 

[The Ruttmeister]

SLS nylon is generally more brittle than FDM. Plus there are far fewer material options... stronger? maybe, depends what you mean by stronger.
And SLS still has issues with 'micro bubbles' encapsulated within the part. (SLS and sintering processes in general cannot produce fully dense parts, ever). That said, the scale of any bubbles or voids inside the part is so small that they are irrelevant compared to the print material, I wouldn't worry about that.

Only advantage that SLS has is this context is surface finish, in every other way FDM it the better choice. Its an open question as to whether that surface finish matters (and can't be solved with a bit of sandpaper).
And for the price of a single SLS part you can buy a couple of spools of nylon or whatever and print a couple of Kg's. Heck, some services you could buy a cheap (rubbish) FDM printer and still save money.
And the SLS part is absolutely going to cost more than the genuine part.

I'd just go ahead and make the part and try it. I'd go with PET, because its much easier to work with than nylon (and doesn't change size with moisture the way nylon does, its a sponge!).
As Seb13 says, its not a pressure bearing part (and if it becomes pressure bearing you have other things to worry about!).

Biggest advantage of making it yourself is actually that you can work on getting the fit perfect (without the time and cost of SLS), which in my experience is the critical factor when replacing screw type fittings with FDM versions. In addition to the basic, "can I make a watertight part" issue, which is generally not a problem any more.
You can't beat a lead time of zero days.

Plus its fun!

And I wouldn't bother with SLA before anyone suggests it, the materials are much less durable and suffer from UV exposure related issues.

 

[seb13]

I've been 3D printing parts for scuba BCDs since several months. I print at 100 % infill with PETG and ABS. Those parts have been used in dives without any broken part. I've also printed with FLEX filament 2nd stage caps and a blind comms plug for an Ocean Reef Neptune Full Face mask with PLA.
All parts have done it's work without any problem.
Many people said that I'm playing with "life support gear", however I print parts because that "life support gear" many times breaks like old paper.

Interesting, so PLA is actually working for part exposed to water. I just "heard" that it's water sensitive, so that's the reason why I was considering PETG for the final part, but my PETG prints are less "clean" than my PLA prints. I would love to use PLA instead.
You also mentioned "blind comms plug for an Ocean Reef Neptune Full Face mask with PLA", that's exactly what I'm trying to do! I would be interested in your design if you are willing to share. I can also share mine. I am particularly interested in the thread type you used. I am using the default ISO thread in Fusion360. Seems to work fine, but wondering what you came up with.

 

[emoreira]

Interesting, so PLA is actually working for part exposed to water. I just "heard" that it's water sensitive, so that's the reason why I was considering PETG for the final part, but my PETG prints are less "clean" than my PLA prints. I would love to use PLA instead.
You also mentioned "blind comms plug for an Ocean Reef Neptune Full Face mask with PLA", that's exactly what I'm trying to do! I would be interested in your design if you are willing to share. I can also share mine. I am particularly interested in the thread type you used. I am using the default ISO thread in Fusion360. Seems to work fine, but wondering what you came up with.

I designed the part with FreeCAD. I copied the thread from the female thread.

 

[seb13]

I designed the part with FreeCAD. I copied the thread from the female thread.
View attachment 560482

Nice job! It's very similar to my first iteration where I copied the surface air valve design with the handles. Then I realized, I actually don't need to move the part while diving and decided to make it low profile with the internal handle. I tried to copy the original design. I'll check the difference between your thread and mine, thanks for the share!

 

[saxman242]

stronger? maybe, depends what you mean by stronger.

The issue with fdm parts are they're incredibly anisotropic due to poor interlayer bonding. SLS parts, in my experience, tend to be far more homogeneous. In this particular case, an fdm part (printed in the orientation that most anyone would print the part) is reacting any loads at the roots of the printed threads entirely through the interlayer bonds. This is the worst possible scenario for that part.

Will it work? Yah, probably, at least for a while. You're not doing yourself any favors by printing it on an fdm machine though.

 

[emoreira]

The issue with fdm parts are they're incredibly anisotropic due to poor interlayer bonding. SLS parts, in my experience, tend to be far more homogeneous. In this particular case, an fdm part (printed in the orientation that most anyone would print the part) is reacting any loads at the roots of the printed threads entirely through the interlayer bonds. This is the worst possible scenario for that part.

Will it work? Yah, probably, at least for a while. You're doing yourself any favors by printing it on an fdm machine though.

Any one has it's own experience. I did print many parts already and it's not as fragile as many think. Proper settings and a correct design are key. It's like driving, could be extremely dangerous if driving wrong.