On Mon, 15 Feb 2010 18:28:26 +0800, "Royston Vasey"
wrote:

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.

I did that today. It's curing in my lab toaster oven right now.

In a word, make a plug that fits or use epoxy, RTV or hot glue to seal
gaps.

I'd made a tube by boring out and turning down ABS water pipe to a
wall thickness of about 1/32". My circuit board was about the size of
a stick of gum, about 5/8" x 2". It has two round cords, one from the
supply and one to the load. I wanted to make this module, the current
regulator, a bulge in the cord.

I turned a plug about 1/8" thick by appropriate dia to fit the tube
with a bop fit -- bop it with heel of hand to get it in. Damned near
airtight. Made that out of fiberglass rod because that's what I had
at hand. (Yes, I protected the ways with a cloth!) I drilled a .110"
dia hole to pass a cord, countersunk it, ran the cord thru it and
drizzled in some 5-minute epoxy to seal that up. When that had cured I
sparingly wiped some 5-minute epoxy on the edge of the plug and bopped
it in. The epoxy was very likely not necessary but what the hell, eh?
I mixed up some Scotchcast 235, a resin intended for encapsulating
electrical stuff. At elevated temperature (about 80C) this stuff is
about as runny as water. It fills nooks and crannies and releases air
bubbles readily. Doesn't stress elex by shrinking because it doesn't
cure brittle-hard like epoxy, it retains a bit of give. Poured it in,
put it in the oven. It'll be "done" tomorrow about lunchtime.