Bob,
Sorry this took a bit of time. I have been laying up my Itch Micro fuses
with the wet seam method. I work fast. I mix up epoxy, and sometimes cool
it down in an ice bath to slow the curing if it is hot out. Anyway, I lay
up each fuse half. By getting the epoxy spread thin, the cure time is
increased. I cut the overlap as soon as I can after getting everything
wetted out, and all air bubbles out of the fuse sides. I then look at how
much epoxy I have left and often mix up a small fresh batch. I try to mix
up as little epoxy as I can since if it is there mixed up, it will get added
to the part and add weight. The first epoxy mixing on the cloth will
stiffen a bit but not much. This I think is an advantage for me. I then
brush a coat of resin along the flush edge of the FG part where the overlap
FG will seam. I then brush excess resin along the outside of the
overlapping FG cloth where the two parts of the mold itself will join. I do
this to make sure that the resin fills in the seam. I also do this because
I try to lay up the main parts with as little resin as I can to keep the
fuse light. When I put the mold halves together I slide the parts sideways
to get the overlapping FG flap to bond to the opposite part. If you have
take a look at my mold pictures you will know what I mean. The excess resin
fills in the seam, and produces a flash around the finished part. The resin
oozes out if there is too much. I cut and sand this off when taking the
part out of the mold. The sooner you put the halves together the better.
The tricky part is getting the overlapping FG to bond flush inside. Years
ago molders told me to run a wet brush on a stick down the length of the
overlapping FG to get it down. The only problem, is that you have to have
some access for the brush to reach. For my Micro fusesand the seamless
method, I take a coat hanger, cut it, bend it straight then on the end I
bend a very tight round. The end will now slide on the FG and I can bend
the coat hanger to reach the wierd spots. Cheap, and you can throw it away
later.
This is where design of the mold is important. Many molds have some open
ends, like for canopies, wing saddles, or even down the tailboom from the
end. If the opening is only via the tail boom, then is it fairly tricky to
reach everywhere. I often cut a portion of the mold out where I know I will
be cutting FG away after the part comes out. In nearly all of the molding
descriptions I have read, rarely do I see this problem addressed. I mayt be
wrong, though. It is very important however. I do not add color, like
black, to my molds as I often hold the mold up to a 100 watt worklight. I
can then seem where the coat hanger reaches, and I know at least I am trying
to get everthing down without bubbles or wrinkles. Often you can sight down
parts through holes and see the seam, just like in a nosecone. This has
take some practice with me, and when I lay up more than 2 parts in a row I
can get this step down well.
For those who see this take a look at my web site to see my references.
http://www.scrollsander.com
I hope this helps.
Chris
>Chris,
>
>Thanks for taking the time to post such a step by step process. For me,
>a picture is worth much more than thousands and thousands of words. I
>am able to fully grasp the the entire process up to a point. It's
>getting the fuze halves together and ensuring the seam is mating
>properly. First, how long after laying up the two halves do you wait to
>actually do the glass trimming? Second, after trimming the two halves
>is there an addition wait time to put the halves together?
>With the nose cone it's easy to see inside and inspect the seam but with
>the closed fuze it seems you are at the mercy of faith.
>
>
>Thanks
>Bob Germano
>[EMAIL PROTECTED]
>
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