On Wed, 10 Aug 2016 10:38:21 -0700, unclhank wrote:

On Wednesday, August 10, 2016 at 1:17:33 PM UTC-4,
wrote:
I have had success in making small fiberglass parts using epoxy over
foam method. I'd get a 4x4x1" sheet of closed cell pink foam from
Homedepo (don't use open-cell styrofoam because it doesn't sand
well),heat shape it to the gentle curve of the front of your trailer,
then sand in a nice radius all around using a long sanding block. Then
lay-on 3 layers of 6oz cloth orientated 45 degrees from vertical. You
must use epoxy because boat resin eats styrofoam. After curing, trim
the edges and dig out the foam.........or, just leave it there, except
where the hinges and handle goes. Fill and paint........seems like I
remember having a red door on my Eberly.
Have fun,
JJ

Further to JJ technique:
If I want the "mold" to go away, I do the following:
After shaping, cover the entire surface with masking tape as smoothly as
practical. Overlaps don't matter.
Wax the heck out of the resulting surface.
Do lay up.
Peel and scrape the foam out after curing.
This is an easier clean up than trying to get foam crap off the layup.
Good Luck UH

Another foam that shapes really nicely with a blade and coarse sandpaper
is DuPont FloorMate - its a blue, non-beaded foam that comes in 4' x 8'
sheets in 1 or 1.5 inch (25 or 35mm) sheets. It is easily glued together
with white PVA or (better) pale yellow aliphatic wood glue. Aliphatic is
better if you're going to sand the assembled item because it sands well
without balling up as PVA tends to do.

Epoxy laminating resin is good for glassing the Floormate: I used
Floormate/epoxy resin/glass to make the male forms I used to mould a set
tie-down tip fittings for my Libelle:

http://www.gregorie.org/gliding/tie-down/

If I was making a Eberle door I think I'd leave the foam in place as part
of the door and put a layer or two of 3-4 oz glasscloth over the inside
of the foam to protect it from dings. The extra weight of doing this
would be small but the resulting door would be a lot stiffer and more
resistant to damage.

===========

For what its worth, surfers used to shape the foam cores of their boards
with a wire brush. This shapes the blocks faster than cutting and sanding
does but don't get too heavy-handed and enthusiastic if you try this
method.


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martin@ | Martin Gregorie
gregorie. | Essex, UK
org |