[PSUBS-MAILIST] Compass Video

[Alan via Personal_Submersibles]

Here's a good article on bonding epoxy to PVC pipe, showing
varying methods & their test results.
https://www.epoxyworks.com/index.php/bonding-pvc-plastic-with-epoxy/
They use a West Systems epoxy but recommend another product. 
Alan


> On 14/06/2019, at 7:16 AM, Sean T. Stevenson via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> These potting compounds are a bit more compliant when cured compared to e.g. a typical marine two part epoxy - particularly the 832FX product. Anything too rigid will have a tendency to break adhesion under strain or thermal shock. Conversely, too soft and it won't hold the pressure, depending on bulk thickness. MG also makes polyurethanes, but I haven't used them personally.
> 
> Sean 
> 
> 
> -------- Original Message --------
> On Jun 13, 2019, 12:52, Alan via Personal_Submersibles < personal_submersibles at psubs.org> wrote:
> 
> Sean,
> interesting; they are not saying it is any more adhesive than normal
> epoxy, but are touting its thermal properties. That makes me think
> that standard epoxy would be OK if the electronics aren't drawing
> much current. 
> Alan
> 
>> On 14/06/2019, at 4:18 AM, Sean T. Stevenson via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>> 
>> My go-to compounds for exactly this application:
>> 
>> https://www.mgchemicals.com/products/potting-compounds/epoxy-potting-compounds/
>> 
>> Sean
>> 
>> 
>> 
>> 
>> ‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
>>> On Thursday, June 13, 2019 7:27 AM, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>>> 
>>> 
>>> Alan,
>>> I have had good luck with epoxy for potting penetrators in metal fittings.  I have pressure tested well past 1,000 psi with good success.  Gamma and E3000 both have 20 pin penetrators using casting resin and were pressure tested above 1,000 psi.  
>>> Having said that, I potted my new compass sensor with epoxy and the sensor has failed possibly.   I have not investigated completely yet.  
>>> I would have concerns now about potting electronics in epoxy.  this is my first time potting electronics,   I would recommend buying electronic specific potting material and keep using casting resin or epoxy for power penetrators.
>>> Hank
>>> 
>>> On Thursday, June 13, 2019, 6:20:21 AM MDT, 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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>> 
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