Reusing an RTV Gasket

[Evan1]

I am making a craft from primarily 3d printed parts. The 3d printed hull contains all of the electronics.
This hull is basically a tub and a lid. They meet at a somewhat flat perimeter surface that will be held together with small wood screws every 15mm. The issue is that this meeting/sealing surface is not perfectly smooth. It has 2 main types of imperfections:
-Slight warping. One area has up to a 0.5mm gap while the rest mates better.
-Micro-ridges. There are very fine ridges that traverse the seal line. I am afraid these could become tunnels for water.

My use case:
I will be using my craft in the ocean but only down to around 2 meters or less. So pressure should not be an issue.

I like the idea of RTV silicon or a similar home formed gasket. I like this because I think it could form to the weird shape of my seal surface.
The downside is that I want to open up the hull frequently. I would prefer not to form a new gasket every time.

Is is possible to reuse a dried RTV silicon gasket? Maybe I could spray thin oil to one of the surfaces so it would only adhere to the other surface?
Or are there soft enough rubber gaskets to handle this? Are there other options for gaskets I should know about?

Thanks in advance for any info!

[Bennachie]

Hi,

There was a very recent discussion of gasket materials here-

viewtopic.php?f=13&t=1975

I'm not sure RTV would work well as a reusable gasket at all. It would tend to be too thin around the areas where your screws went through, plus it is not under any compression, unless you made the gasket with the screws not fully screwed down, then tightened them a bit once the RTV had set. Better making a proper gasket.

Another tip if using a box-with-lid type of housing is to mount it upside down, with the lid at the bottom, and make sure all your penetrators are mounted through this lid. That way, if the edge seal or penetrators leak, the main part of the box will act like a diving bell and not let much water in (if you're only going to a couple of meters depth).

[Evan1]

Ok thanks for the good ideas. I am now thinking a really soft seal could work well. Maybe 30A-40A. I'll try a couple and see what works.

[Lucas]

I think the 3D printed hull is likely going to be more trouble than it's worth. Unless you have engineered a solution around it, even at 100% infil water will still easily penetrate 3D printed material. I believe Steve's build thread talks about some of the testing he did in that realm.

Maybe coating it with a resin or similar could make it work for your use-case?

[Evan1]

I think I found the solution to my gasket surface issue- I just needed to sand down the 3d printed sealing surfaces. I was able to get these surfaces to be almost perfectly flat with almost a glass smooth finish. I am doing testing now, but I suspect they will seal well with my 1mm thick 30A gasket.

I will evaluate if the prints themselves are waterproof soon. I suspect they are. What I do to keep them waterproof:
- 104% flow rate
- 1.0mm nozzle
- concentric infill
- 5 mm thick walls