Royston Vasey wrote:
"Ed Huntress" wrote in message
...
"Royston Vasey" wrote in message
. au...
I'm trying to seal a printed circuit board into a PVC part I've turned
out on my lathe. The problem I'm having is the that the epoxy goes quite
runny as it goes through its curing process and some of it runs through
small gaps ( 0.5mm) where I'd prefer it didn't.


I'm using CW177 resin & HY177 hardener in the 5:1 mix recommended.

The data sheet is he

http://www.meury.com.au/uploads/170666853166.pdf

I tried some rapid set epoxy (~90 seconds) but it turns to crap before I
can get it in where it needs to go.


It's not really practical to use anything else (like RTV, tape, hot glue
or wax etc) to seal the small gaps in the bottom of the assembly.

Has anyone played around with this type of problem?

thanks.
As Lloyd an others have suggested, straight epoxy is going to be a problem
if you need to overcome its tendency to run. In fact, it's inherently
anti-thixotropic -- just the opposite of what you want. Epoxy drools.

The two usual solutions are to add a thickener, which doesn't directly
address the problem but which slows down the running, or to add a
thixotrope. That's the better solution in most cases although you have to
be careful because the suppliers usually aren't very clear about what
their products actually do -- thicken it, or make it thixotropic. There
are a couple of other possibilities, like rotating the part slowly while
it's curing, or applying the epoxy in steps, to one plane at a time, and
making sure the plane to which you've applied it is held horizontal while
it's curing. I can't picture your application but it sounds as if these
solutions wouldn't work for you.

Not being up on the latest, I can't give any specific recommendations, but
I'd follow the suggestions of people who understand the difference between
these two properties.

--
Ed Huntress


I agree, sounds like an expoxy with a thixotrope is what is needed. It's not
really practical to do it in multiple steps.



Like I said... West 406. Fumed silica is the preferred agent.
Mix to consistency of mayonnaises to peanut butter and trowel it in.


--

Richard Lamb
http://www.home.earthlink.net/~cavelamb/


"The clock of life is wound but once, and no man has the power
to tell just when the hands will stop, at late or early hour...
Now is the only time you own. Live, love, toil with a will.
Place no faith in time. For the clock may soon be still."