I redid a fuse plug a while back. I was very pleases with the result,
but it took allot of time.
I took my mold, waxed it as best I could. I them mixed a whole bunch of
west systems (any high quality epoxy will do) epoxy and mixed it with
cab-o-sil (fumed silica) to make a good, thick paste. I then smeared the
goo in the fuse surface of the mold, keeping the epoxy only on the fuse
surface, not the mold flange. This coating was about a quarter to a half
inch thick.
I did this, coating both halves of the mold with the epoxy goo making a
good carvable surface. after both sides had set, I mixed more of the
epoxy/silica goo and applied a liberal coating to the mold seem and joined
the two mold halves to create a seamless new, one-piece plug.
After all the epoxy cured, I filled the hollow space with plaster for
structural support. Note: one point of my mould was open enough to do this,
so if your mould has no opening, you may have to make one.
After this was completely cured, I cracked the plug out of the mold.
This was where things when wrong. It turns out the thick epoxy layer
generated enough heat in the curing stage that it actually melted the
release wax and bounded to the resin of the mold. This resulted in chunks
of the first mold to be broken off and stuck to the new plug. I had to
chisel and grind away at these chunks until they finally cracked off.
The old mold ended up in more than the original two planned pieces.
Chips of the mold were missing and the mold was lost forever.
Now, looking back, I realize this could have bean avoided had I made a
thin (less than a 16th of an inch) gel or surface coat, allowed that to
cure, then added the thick pasty coat of epoxy goo. This surface coat would
have saved them mold by not melting the wax, and allowing the part to
separate.
Still, this process can be risky if you value your mold and your time.
I would only do this if you don't plan on using your current mold or can
make a new one out of the original plug.
Best of luck,
Erik Alber
"The Resin Head"
http://SuperSailplanes.freeservers.com
http://NuanceHLG.8k.com
----- Original Message -----
From: "Mark Miller" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Friday, February 16, 2001 9:51 AM
Subject: [RCSE] Plug Question
> I have a mold for a fuselage which I would like to
> modify a bit. I would then like to make a mold of the
> modified part. I do not want to destroy the original
> plug I have for the mold. Does anyone know of a
> substance I can put in the mold to make a copy of the
> plug which I can then make the modifications to. I was
> thinking of some kind of epoxy concoction but I think
> it might be hard to deal with. Plaster of Paris is
> another thought but I'm not sure. I seem to remember a
> molding prototyping substance which is easily carved
> and sanded but firm enough to make a mold of. Any
> thoughts out there?
>
> cheers,
>
> Mark
>
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