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Topic: Sealing an ABS with clear window to make it waterproof (Read 8481 times) previous topic - next topic

windoze_killa

I want to put an 1.3" OLED display ina small ABS case. It will have a window in it (obviously) so you can see the display.

Question is, how do I seal this window? I would like it to look professional. The hole will be CNC cut so nice smooth edges. I have thought of silicon but it can be messy.

Any ideas?

Paul_KD7HB

You failed to identify the material the window is made from. Until you decide that, sealing material decision is impossible. Does you CNC cut leave a ledge for the window material to set on?

The very best sealing material is that used to seal automobile wind shield/screen glass to the metal body.

Paul

windoze_killa

Thanks for your reply. At the moment I have no idea what the window will be made of but probably thin polycarbonate (1.5 - 2mm)

kionokitse

Try a solvent cement with methylene chloride. This works really well on both materials. Methylene chloride solvents tend to be fairly non-viscous, so make sure your joint is tight to start with. I'd also do a quick test with some scraps to get used to the process. Methylene chloride will dissolve ploy-carbonate quickly so if you get any on the middle of that window that's a big no no. This will also work on acrylic if you choose to go that route. Here is a link to a product I found.

https://www.amazon.com/Weld-Acrylic-Adhesive-Applicator-Bottle/dp/B0096TWKCW

windoze_killa

Thanks. I have used that before and yes it is a pain when you get it where you don't want it (and keep your minds out of the gutter). I like the car window sealer idea. Bitumastic is easy to remove with a bit of alcohol. I just hope it is good enough to stay sealed. This ABS box with be on a motor bike handle bar or head stem.

Paul_KD7HB

Thanks. I have used that before and yes it is a pain when you get it where you don't want it (and keep your minds out of the gutter). I like the car window sealer idea. Bitumastic is easy to remove with a bit of alcohol. I just hope it is good enough to stay sealed. This ABS box with be on a motor bike handle bar or head stem.
Please tell us the device is completely self contained. No wires or other stuff going through holes in the box.

Paul

windoze_killa

There will be wires coming out. Some to power and others to sensors. the back half will be filled with epoxy so that part of it will be fine. I am just worried about the OLED display.

Paul_KD7HB

There will be wires coming out. Some to power and others to sensors. the back half will be filled with epoxy so that part of it will be fine. I am just worried about the OLED display.
That is what I suspected. You are going to put this device on a moving vehicle that is subject to rain and blowing rain and wind-driven water. Water loves stranded wire because capillary action makes it move through the twisted strands. Wind driven water moves even faster. Let me describe the electronic control unit we used to make for a motorcycle manufacturer.

The box was a commercial ABS box that was machine to accept waterproof automotive connectors on the box ends. After testing, we used RTV to seal the edges of the connectors to the box openings because the epoxy potting compound was as fluid as water and took 24 hours to completely set up. There were NO wires going into the box! A gasketed cover completed the box.

In use the box was mounted under the motorcycle seat to further protect it from water. Epoxy potting limits water getting to your device, but is not completely water-proof. Just takes longer!

Paul


windoze_killa

The far end of the wires will be terminated in sealed auto connectors, the same as already used on the bikes. I have been producing similar items (without displays) for nearly 10 years without a single failure so I am confident that side of the project will seal fine. The epoxy I use is only 5 minute stuff as I found the 24 hour stuff wicked like water just as you said. Any wicking at the box end actually aids in the sealing. Having said that I have also considered a socket on the box but I don't think i can find a sealed one small enough. The box is only going to be 50mm x 40mm and about 20mm high.

Paul_KD7HB

I think your experience proves your methods are working, so don't change! Most any sealed automotive connectors are available, but we found the minimum order quantity of 1,000 might limit smaller manufacturers like yourself. The motorcycle company went out of business in 2008 and the owner literately disappeared owning us a bit of $. I could not find a buyer for the remaining connectors. They were all paid for. So, I ended up putting them in the dumpster.

Paul

windoze_killa

NOOOOOOOOOOOOOOOO.

What connectors were they and how big?

CrossRoads

#11
May 26, 2020, 05:46 am Last Edit: May 26, 2020, 05:47 am by CrossRoads
Have you looked at NEMA rated enclosures here?
https://www.polycase.com/nema-enclosures

"NEMA enclosures and boxes are weatherproof and waterproof, designed to protect sensitive internal equipment in harsh outdoor or indoor environments."

They'll do custom too.

And NEMA rated glands for wires, use the filter on the side to select the desired rating level.
https://www.polycase.com/catalogsearch/result?q=gland
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

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