[PSUBS-MAILIST] Compass Video

[Alan via Personal_Submersibles]

Jon,
I like the choice of PVC & think it would be quite strong, & if you
potted inside, even stronger.
I am paranoid as I have destroyed a lot of electronics with salt water.
And had water sucked up inside the wire jackets for a metre due to
heating & cooling.
Maybe on the compass project strip a section of the wire going through
the epoxy & use one of the techniques in the link to improve the PVC
bond X 3 times. And go over the board with the epoxy. Was doing this 
on my LED driver last night.
Alan



> On 14/06/2019, at 9:32 AM, Jon Wallace via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> Alan, all great points and I wouldn't argue against them.  You may be right about the epoxy/pvc adhesion, and as usual the internet isn't much help.  I can find as many "don't do it" as "it works fine" opinions out there.  I should have scuffed it up a bit though, that would have helped with adhesion.  In the past I have fabricated my own "blue globe" fittings out of brass compression fittings but I wanted all plastic so I wouldn't have to worry about decay of the brass by salt-water.  I mentioned a couple of times in the video that this was a non-critical component but maybe should have impressed that a bit more on the viewer.  PVC certainly would not be my choice for a critical application.
> 
> Jon
> 
> 
> On Thursday, June 13, 2019, 08:22:08 AM EDT, Alan via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> 
> Jon,
> that was one of the most comprehensive "How to" videos I've seen.
> Have one of those compasses so will emulate that.
> I have reservations about epoxy sealing the wires though.
> I did a lot of experiments with glues & PVC wire jackets & found a lot of
> the glues disappointing. I found one product specifically for PVC boats
> that stood out.
> I have mentioned before that I potted a couple of wires for 1" in to a WD40
> filled housing & the WD40 just ran out between the epoxy & wire jacket
> without pressure. 
> Under pressure I would guess that the PVC jacket would be more compressible
> than the  epoxy resin around it & would tear away from it, letting water in.
> Suggest epoxying the whole board both sides & the wires where they are 
> soldered on, in case of water egress.
> I have strong reservations about the epoxy sticking to the PVC pipe also.
> I would be interested in others opinions on this as potting wires is 
> something we are doing a lot of.
> Alan
> 
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