Homebuilt ROVs Forum

I am thinking of 3D printing a flange for 4" PVC pipe that will allow me to secure a piece of acrylic. 100% fill, using PLA. I will probably use a smoothing compound to get the piece as smooth as possible.

The pipe-facing side would have a deep groove that will be partially-filled with marine epoxy to create a watertight seal around the pipe. The other side will be smooth to allow for a gasket sandwiched between the acrylic and the flange. The acrylic will be secured using 12 machine screws and nuts/washers.

An image is attached.

Do you think this will work for depths of approximately 100'/33m?

Yes, I think it would.

If the gasket face is the side which lies on the print bed, which I assume it is, then you might not even need to use a smoothing compound. You want that face nice and smooth but you might actually be better leaving the area that is to be bonded with epoxy as it will adhere better to a slightly rough surface.

I've tried this SEE HERE and it didn't work.

I also make a lot of 3D Printed fishing lures and I full coat them with epoxy and I've still had pin holes that can fill the lure up even at 8-10 feet of depth... when they get back to the surface they are like a squirt gun.

You can try it but I highly recommend fully testing the chamber before putting anything inside it that can get ruined.

-Steve

Thanks for the reply.

So the issue isn't the epoxy/PVC interface, but the PLA itself?

OK, so then what I might wind up doing is using flanges from plumbing supply house, similar to: https://www.pvcfittingsonline.com/851-0 ... lange.html and cutting acrylic to seal it up with bolts and the accompanying gasket kit.

Do you think that is a better option?

Another option if you want to use your original design is to have it 3D printed by a company such as Shapeways. They use a sintered plastic method and I believe that nylon parts made this way are waterproof.

Look into printing it with PETG. It's supposed to be waterproof and strong. I'm going to buy some and experiment with it, maybe print some floats and weigh them down to see how deep they'll go without leaking/imploding.

perry wrote:So the issue isn't the epoxy/PVC interface, but the PLA itself?

Yes even printing at 100% it's not going to be as solid as you think it's just the nature of 3D printing.

Materials like Ian mentioned such as PETG may have claims of being waterproof but I believe its only refereed to as waterproof when people are making vases out of it. I seriously doubt it would hold up to any kind of pressure... but if anyone does try it post the results so we all know for sure.

-Steve

I knew that PLA wasn't exactly solid, but I was hoping that coating it in (read: dunking it in) epoxy would have been sufficient.

I am not going to pay for 3D printing services, particularly for unknown materials.

I keep going back and forth with threaded PVC fittings, gaskets and flat end caps with external collars and lengths of external threaded rod. I'm even thinking about getting small cutting boards (HDPE) from the local dollar store and milling out a circle and laying a gasket in the groove and tightening it down with threaded rod.

Threaded fittings would be OK, but they seem unreliable. At least with face-sealing an O-ring or gasket, you know you have contact.

My current thought is to just get SCH80 4" flange and either cutting a groove for an O-ring or just using the commercial gasket and cutting acrylic for over the end.

Thoughts and opinions?

Do you need stuff printed?

In the Netherlands and probaly also in other locations you can also use metal in 3D printing at some shops. That should hold up to pressure better than platics and easier to make waterproof afterwards in case of small leaks.