[PSUBS-MAILIST] Fiberglass
hank pronk via Personal_Submersibles
personal_submersibles at psubs.org
Mon May 4 17:51:51 EDT 2015
Alan,
Oh I misunderstood, I hate fiberglass! :-)
Hank--------------------------------------------
On Mon, 5/4/15, Alan James via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
Subject: Re: [PSUBS-MAILIST] Fiberglass
To: "Personal Submersibles General Discussion" <personal_submersibles at psubs.org>
Received: Monday, May 4, 2015, 5:38 PM
Hank,I mean
when the fiberglass has cured & just the surface is
tacky.It is
meant to be like this to form a chemical bond with the next
layer.If you
wait for the surface to dry (in time) then the next layer
doesn't adhere as well.I used
clear cast polyester resin in art works, & you had to
add paraphin wax inliquid
form to stop the surface becomming tacky.There are two general types
of polyester resin used for repair. Laminating or Bonding
resin which cure to a tacky surface and Fiberglass or Marine
Finish resin which cures to a non-tacky
surface.Laminating
resin (Evercoat # 100560, 100561)
is used for initial coats on wood or for multiple
applications with fiberglass cloth or mat. This resin is
air-inhibited which means it will cure to a tacky finish and
does not require sanding between coats. This is desirable in
laminating because the layers adhere to each other better.
This product should not be used as a final coat unless
measures are taken to seal out the air during the curing
process.Marine and Fiberglass resin (Evercoat # 100553, 100552,
100554, 100517, 100518, 105499, 105498, 105500, and 105501)
is non air-inhibited or waxed
resin. It is for the final coat. This resin cures
with a hard non-tacky surface. When the catalyzed resin is
applied as a final coat to the laminate coats of resin, the
wax rises to the top, sealing off the air and allows the
resin to cure to a hard finish, which can then be sanded,
painted or gel coated.NOTE: Cannot be used with
aluminum, redwood and/or close-grained woods like oak or
cedar. Do not use with Styrofoam.Alan
From: hank pronk via
Personal_Submersibles
<personal_submersibles at psubs.org>
To: Personal
Submersibles General Discussion
<personal_submersibles at psubs.org>
Sent: Tuesday,
May 5, 2015 9:14 AM
Subject: Re:
[PSUBS-MAILIST] Fiberglass
Alan,
Tacky
means weak hardener ratio or poor mix. Tricky stuff!
Hank--------------------------------------------
On Mon, 5/4/15, Alec Smyth via
Personal_Submersibles <personal_submersibles at psubs.org>
wrote:
Subject: Re:
[PSUBS-MAILIST] Fiberglass
To:
"Personal Submersibles General Discussion" <personal_submersibles at psubs.org>
Received: Monday, May 4, 2015, 5:11 PM
Hi
Alan,
Interesting comment
about the
polyester being designed for one shot. The
polyester resin I used is from 3M and the instructions
say
that it you restart the job on a cured
layer you should sand
it lightly first - so
that's what I did, since it took
about
a month to get the desired number of layers on. It
didn't seem to have any bonding issues
with layers
applied on cured material. This
particular 3M polyester
cures fully in 2
hours, and didn't feel tacky after
that, so perhaps this is brand specific.
Good point about the sections
helping make the mirror versions of the MBTs. I made
templates out of thin particle board to cut
out the foam
sections, and by flipping the
templates was able to make
mirror image
tanks.
Best,
Alec
On
Mon, May 4, 2015 at 4:33
PM, Alan James via
Personal_Submersibles <personal_submersibles at psubs.org>
wrote:
Hi
Scott,some great ideas
from Alec there.I
like his
idea of using sandwiches of
thinner sheets of
polystyrene.You should
be
able to trace a shape on one sheet, cut
it out,
thencopy around it on to
the corresponding sheet of the mirror
imageballast tank, to get two tanks that are
identical.When I did mine
I
marked the hull with a felt pen as to where
theballast tank was going
to fit against
it. I covered this area with
plasticfood
wrap. I then
draped glass mat over
it & epoxied about 3
layers over
this. Polyester resin will
disolve the
plastic food wrap. This approach may be a
problemon vertical walls & there
may be
a similar appoach that works better.You need to embed this
shape in to the polystyrene
section by wire
brushingout the
polystyrene untill it's
a good fit. Because of shrinkage
of the
fiberglass& warping it
won't
nessecarily be a perfect match & may require
additional work.Once you have the
polystyrene shape done you cover it with
fiberglass & go
overthe area you formed
against the
hull.I used epoxy because it
can go
straight on to the polystyrene (test
it first)
&you can spend a month
slowly
building it up, whereas polyester
resin is
designedto be laminated in one
shot. It
is air inhibited & remains
tacky on the outersurface unless it has a wax additive.I
once made a 1/4 size ambulance out of
polystyrene using mainly achain saw.
Great
fun but one hell of a mess.Alan
From: Alec
Smyth via
Personal_Submersibles <personal_submersibles at psubs.org>
To: Personal
Submersibles
General Discussion <personal_submersibles at psubs.org>
Sent: Tuesday, May 5,
2015 3:33 AM
Subject:
Re:
[PSUBS-MAILIST] Fiberglass
Hi
Scott,
Coincidentally your timing is
really
good, because I just finished four
rather complex-shaped
MBTs for the new sub.
Since my sub is a one-off rather than
a
series production item, I used the method of glassing
foam
plugs that are then dissolved, rather
than making molds. To
summarize:
- The plugs
are a sandwich of
many layers of pink home insulation foam
from HomeDepot. When I did Snoopy's saddle tanks I
cut
out the sections with a hot wire, but
this time I realized
my jig saw does the
job in about a tenth the time. Step one
is
to cut a whole bunch of sections and glue them together.
If I weren't so tight-fisted, the ideal
solution here
would be to mill a single
block of foam using CNC equipment,
but I
get by with what I have on hand if it'll save
money - and a milling job would probably take
quite a lot of
it.
- The
glued
sections are only a rough draft of
the final form. Next you
have to shape them
until the steps between sections are gone
and everything is nice and smooth. I use three tools to
go
from the draft to the final product, in
this
order:1) A plain old wood saw2) A
Stanley Surform shaver, with flat and or
rounded blade
fitted depending on the
surface. This thing is absolutely
essential
and I use it for 99% of the job. See http://www.stanleytools.com/default.asp?CATEGORY=SURFORM+TOOLS+AND+BLADES&TYPE=PRODUCT&PARTNUMBER=21-296&SDesc=Surform%26%23174%3B+Plane+Type+%96+Regular+Cut+Blade3)
Sand paper
I'm
afraid I have no scientific answer to ensuring
symmetry. I
just put the plugs side by side
and do a bunch walking in
circles, taking
measurements, and using a level. The plugs
won't come out identical, but close enough to be
functional. This part is more sculpture
than
science.
- Next,
paint
the plugs with several coats of
water-based paint. This is
to prevent the
resin from dissolving them. Water-based
because if not you run the risk of the paint dissolving
the
foam.
- Now apply
layer after layer of wetted fiberglass cloth.
I don't
mean all in one sitting, I mean
iteratively for about a
month. There are
two main considerations then, cloth and
resin.
I can't
give
you a specific recipe for cloth or the cost for cloth,
because I used a combination of material I
already had on
hand and new stuff. I have
purchased from http://www.fibreglast.com
in the past, but this time found lower prices
on eBay for
what turned out to be perfectly
good material. Mostly I used
6.5 oz (quite
light) cloth so that it would drape better,
but that depends on the shape of your tanks. For
instance,
on the inside face that goes
against the hull, you can get
away with
much heavier material since its a gentle curve in
just one plane, and the same goes for any flat
surfaces. But
if you have compound curves
or tight curves its way more
challenging to
drape cloth without forming air bubbles. I
make the walls that go against the hull thinner, since
they
aren't going to be banging against
things like the outer
or upper faces will.
On average I probably put down ten to
fifteen layers of cloth. The pros use vacuum bagging to
prevent bubbles. With my caveman fiberglass
skills I just
try to avoid them in the
first place by selecting
better-draping
cloth, and when I get a bubble I remove it
with a flap wheel before putting down the next layer. In
the
middle of my layup I put down several
layers of Kevlar. This
material is trickier
to work with than fiberglass, it
can't
be sanded and once cured you can only really go
through it with carbide tools. The idea is to
increase
survivability by making the MBTs
puncture resistant. If I
hit a rock or a
dock I still expect the resin might crack,
but it should be quite hard to put a hole in the Kevlar.
You
might think this hard layer should go
on the outside, but I
put it mid-schedule
so I could sand imperfections out of the
fiberglass layers above it.
This job (new
sub, not Snoopy's
tanks) took ten
gallons of resin. Everyone will tell you
epoxy is stronger than polyester resin. However, epoxy is
$76 per gallon vs. $34 for polyester, and
Snoopy's
polyester tanks have held up
perfectly well for years. So,
for me, this
is a case of cheaper-is-sufficient and I went
with polyester.
-
Iteratively sand and fix imperfections with a
fairing
compound. I used West Marine's
#410 fairing filler (http://www.westmarine.com/buy/west-system---410-microlight-filler--P004_120_004_016).
You can do this with Bondo as well, but #410
is easier to
sand.
-
Dissolve the
plugs. When I made
Snoopy's saddle tanks the pink foam
dissolved instantly with gasoline. This time, despite
being
the same brand foam it was somehow
gasoline resistant, but
acetone did the
job.
Best,
Alec
On
Mon,
May 4, 2015 at 9:22 AM, via Personal_Submersibles <personal_submersibles at psubs.org>
wrote:
Alec,
I
was curious if you could go into details about the
making of your saddle tanks?
*Where did you get the foam and
fiberglass and what
types did you use
*How did you shape the foam to ensure symmetry
*Was there any difficulty or anything you
would do
differently
Thanks,
Scott Waters
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