<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
<META http-equiv=Content-Type content="text/html; charset=iso-8859-1">
<META content="MSHTML 6.00.6000.16587" name=GENERATOR>
<STYLE></STYLE>
</HEAD>
<BODY bgColor=#ffffff>
<DIV><FONT face=Arial size=2>Robert</FONT></DIV>
<DIV><FONT face=Arial size=2>Do you need to use any moisture with the
polyurethane ?
Nat</FONT></DIV>
<BLOCKQUOTE
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=rgc1701@earthlink.net href="mailto:rgc1701@earthlink.net">Robert
Campbell</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A
title=nsrca-discussion@lists.f3a.us
href="mailto:nsrca-discussion@lists.f3a.us">nsrca-discussion@lists.f3a.us</A>
</DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Monday, January 07, 2008 12:41
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> [NSRCA-discussion] Vacuum
Bagging - More Info</DIV>
<DIV><BR></DIV>
<DIV><FONT face=Arial size=2>I've just rejoined the discussion list and
noticed a great discussion on vacuum bagging. I also have the low cost
ACP vacuum bagging system and I love it. I've done wings for a couple of
sport models and a few EDF kits and am very happy with the
results.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Someone posted that the ACP system draws a 3 psi
vacuum. That seems about right. If you do the math for a 200 sq in
wing panel, that's equal to stacking 600 lbs on top of your wings! And,
the pressure is perfectly distributed, ensuring a solid bond between the skin
and the core.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>One trick I started doing a few years ago is
using polyurethane glue (Gorilla or Elmers Pro Bond) instead of epoxy.
My technique is to edge sand the skin sheets and then tape then together on
the outside of the skin. I then apply the glue to the inside of the skin
and take an old credit card to squegee off the excess. I leave just
enough glue to make the skin appear damp. I then place the skins on the
core, wrap with breather cloth and insert into the bag. I then place the
assembly back into the cradles and add some weight (2 large books are enough)
to stabilize the assembly. Once I'm happy with the alignment of the
cradles, skins, and cores, I start the pump and let it run 18 to 24
hours. The next evening I have a very light, perfectly skinned
wing. The bond is extremely strong because during the curing process,
the glue soaks into the skins and it foams and works its way down into the
core. The glue also seeps into the butt joints of the skins
and bonds them with virtually no ridges on the outsides of the
skins.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>I've become a firm believer in vacuum
bagging.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Rob</FONT></DIV>
<P>
<HR>
<P></P>_______________________________________________<BR>NSRCA-discussion
mailing
list<BR>NSRCA-discussion@lists.nsrca.org<BR>http://lists.nsrca.org/mailman/listinfo/nsrca-discussion</BLOCKQUOTE></BODY></HTML>