Subject: Re: [harryproa] Re: cling wrap
From: Rob Denney
Date: 5/14/2009, 8:00 PM
To: harryproa@yahoogroups.com.au
Reply-to:
harryproa@yahoogroups.com.au



The scrim is on the Polycore. It is different to the scrim that holds
segmented foam or balsa together.

Holes in the core refers to foam or balsa, and let air and excess
resin through to the top surface where the air is vacuumed and the
excess resin absorbed into the bleeder material.

The panels are very stiff if glassed both sides and bend about as much
as ply of the same thickness, but are much lighter above about 6mm.
Glassed on one side they are fairly easy to bend in a simple (not
compound) curve. Bending should be done slowly and evenly or,
particularly with Polycore, it will bend unevenly.

regards,

Rob

On Fri, May 15, 2009 at 4:51 AM, Malcolm Phillips
<malcolmdphillips@gmail.com> wrote:
>
>
> This has been an interesting thread.
>
> By scrim did you mean the holes in the core to let the air through to the
> top,
> or peel-ply under the panel?
>
> I assume that once you have made a panel you bend it into shape as if it was
> plywood?
> How easy is it to bend? Do you have to do it before it is fully cured or
> anything?
>
> thanks
> Malcolm
>
>
> On Thu, May 14, 2009 at 11:21 AM, Rob Denney <harryproa@gmail.com> wrote:
>>
>>
>> True, as far as excess resin is concerned, so you need to be more
>> careful with your application. However, the scrim lets air through so
>> there are no voids.
>>
>> On Thu, May 14, 2009 at 10:51 PM, Robert <cateran1949@yahoo.co.uk> wrote:
>> >
>> >
>> > -in polycore there is no such thing as a 1mm diameter hole. this adds
>> > 1kg
>> > /m2. a dispersal medium loses the finish of the table. no such thing as
>> > a
>> > free lunch-- In harryproa@yahoogroups.com.au, Rob Denney <harryproa@...>
>> > wrote:
>> >>
>> >> The foam is perforated (1mm dia hioles every 100mm or so. Lets the
>> >> air and the exces resin out. Without the holes or a dispersal
>> >> material underneath, you invariably get a huge air bubble where the
>> >> vaccum cannot reach, regardless of how much resin is in there.
>> >>
>> >> regards,
>> >>
>> >> Rob.
>> >>
>> >> On Thu, May 14, 2009 at 8:31 PM, Robert <cateran1949@...> wrote:
>> >> >
>> >> >
>> >> > I was wondering about the ability to remove excess resin when making
>> >> > wide
>> >> > panels. I was thinking about single panels to make the bottom and one
>> >> > and a
>> >> > half sides of the lw hull, about a 2.4 wide panel at its widest.
>> >> > Derek
>> >> > used
>> >> > to do it on the table without bleeding or dispersal medium
>> >> > underneath. I
>> >> > suppose very careful measuring of resin would allow this.
>> >> > In tropics, too long exposure to humidity can cause problems with
>> >> > epoxy,
>> >> > but
>> >> > If you are immediately covering it , then I suppose it is not a
>> >> > problem,
>> >> > regards,
>> >> > Robert
>> >> > --- In harryproa@yahoogroups.com.au, "Herb Desson" <squirebug@>
>> >> > wrote:
>> >> >>
>> >> >> Hi Rob,
>> >> >>
>> >> >> Not sure about the clingfilm manufacturer - the label is in
>> >> >> Thai. Will see what I can find out about the thickness - it isn't
>> >> >> much
>> >> >> thicker than kitchen use film, but tough enough you can stand on it
>> >> >> to
>> >> >> unroll it without puncturing it (just once). I do all my work in
>> >> >> bare
>> >> >> feet,
>> >> >> to reduce dust and punctures.
>> >> >>
>> >> >> The ground I use is a fairly smooth concrete carport (i.e., garage
>> >> >> without
>> >> >> walls) floor. Not as smooth as a formica table probably, but no
>> >> >> seams.
>> >> >> Since
>> >> >> I only do the top side, the core smooths out any minor unevenness
>> >> >> and
>> >> >> probably would hide any local uneveness less than 1/2 inch. My
>> >> >> maximum
>> >> >> local
>> >> >> unevenness is maybe 1 millimeter.
>> >> >>
>> >> >> The carport works fine for the dory, and may be ok for an
>> >> >> elementarry
>> >> >> size
>> >> >> boat. Bigger than that I will need to make a bigger carport or shed,
>> >> >> which
>> >> >> is not a problem for me as I have 4 hectares to work with.
>> >> >>
>> >> >> What I do is unroll the film, put the foam core on it, which mostly
>> >> >> keeps
>> >> >> it flat - beer bottles work pretty well to stop it from clumping in
>> >> >> the
>> >> >> breeze. Then I unroll the top layer of film and re-roll it (so I can
>> >> >> unroll
>> >> >> it quickly after the resin is applied. Then I apply the fiberglass
>> >> >> (top
>> >> >> side
>> >> >> only), peel ply and vacuum set up. Then I unroll the film and do a
>> >> >> dry
>> >> >> run
>> >> >> to check that the vacuum will work.
>> >> >>
>> >> >> After that I re-roll the film, apply the resin by pouring and
>> >> >> rolling
>> >> >> (or
>> >> >> pushing it around by gloved hand), unroll the film and apply vacuum.
>> >> >> I
>> >> >> am
>> >> >> not doing infusion, just vacuum to remove extra resin. Very simple
>> >> >> really. I
>> >> >> don't see much need to do two sides at once and hence no need for
>> >> >> infusion.
>> >> >>
>> >> >> I have had no problems seeing where the film is, maybe because it is
>> >> >> a
>> >> >> bit
>> >> >> thicker or maybe because I have shaded outdoor light, which is
>> >> >> easier
>> >> >> to see
>> >> >> film in, instead of shop lights.
>> >> >>
>> >> >> For panles much bigger than 1 square meter this really works much
>> >> >> better
>> >> >> with assistants to control the film when unrolling after applying
>> >> >> resin. It
>> >> >> can get quite anxiety provoking and messy if it starts clumping with
>> >> >> a
>> >> >> time
>> >> >> limit. Other than that step I have so far done everything by myself.
>> >> >>
>> >> >> I hadn't heard about bleeder cloth until today - guess I didn't do
>> >> >> enough
>> >> >> research, but I am happy with my work around. I think I still need a
>> >> >> bit of
>> >> >> peel ply to keep the vacuum hose from sticking to the panel, or at
>> >> >> least to
>> >> >> make it easier to take off - I find it difficult to remove the hose
>> >> >> when
>> >> >> resin accumulates without peel ply. But the peel ply can be only
>> >> >> about
>> >> >> 6
>> >> >> inches wide, just enough to make the hose easy to remove. The vacuum
>> >> >> hose is
>> >> >> 5/8 inch clear plastic hose cut in a spiral that I lay around the
>> >> >> panel
>> >> >> and
>> >> >> inside the shop vac hose. The cling film covers everything.
>> >> >>
>> >> >> Best regards
>> >> >> Herb
>> >> >>
>> >> >> --- In harryproa@yahoogroups.com.au, Rob Denney <harryproa@> wrote:
>> >> >> >
>> >> >> > G'day,
>> >> >> >
>> >> >> > Good stuff! I have tried cling film in the past, but it was too
>> >> >> > hard
>> >> >> > to see where it was and wasn't. That was only 300mm wide. Any idea
>> >> >> > what thickness yours is? And who is the manufacturer?
>> >> >> >
>> >> >> > How do you keep the sheet flat if you bag it on the ground?
>> >> >> >
>> >> >> > It sounds as if you are not using a bleeder cloth? This goes on
>> >> >> > top
>> >> >> > of the preforated plastic on top of the peel ply and soaks up
>> >> >> > surplus
>> >> >> > resin, so there is none available for lumps.
>> >> >> >
>> >> >> > If you are sanding the panels anyway, peel ply is not required.
>> >> >> > The
>> >> >> > ATL resin is great stuff, has out times of several days if
>> >> >> > required.
>> >> >> >
>> >> >> > regards,
>> >> >> >
>> >> >> > Rob
>> >> >> >
>> >> >> > On Thu, May 14, 2009 at 1:33 PM, Herb Desson <squirebug@> wrote:
>> >> >> > >
>> >> >> > >
>> >> >> > > Hi,
>> >> >> > >
>> >> >> > > I have been experimenting with a 4 meter dory before starting on
>> >> >> > > a
>> >> >> > > harryproa
>> >> >> > > and have learned a few things that might be interesting.
>> >> >> > >
>> >> >> > > 1. I have found some large rolls of 1.4 meter wide heavy duty
>> >> >> > > clingfilm/saranwrap at the local diy. It has all the usual
>> >> >> > > properties
>> >> >> > > of
>> >> >> > > clingfilm - sticking together, clumping etc. But also doesn't
>> >> >> > > need
>> >> >> > > to
>> >> >> > > be
>> >> >> > > taped and holes can be plugged after applying vacuum just by
>> >> >> > > dropping
>> >> >> > > a a
>> >> >> > > small piece on the hole. Holes are very rare so far. I am using
>> >> >> > > a
>> >> >> > > shop
>> >> >> > > vac
>> >> >> > > at the moment (may change later) and find that the film makes a
>> >> >> > > good
>> >> >> > > seal
>> >> >> > > around the non-smooth hose. I have had no problems with the film
>> >> >> > > breaking
>> >> >> > > under vacuum.
>> >> >> > >
>> >> >> > > 2. With the cling film I don't need a table - just use a double
>> >> >> > > length
>> >> >> > > of
>> >> >> > > film at least for narrow panels, which is all I need for the
>> >> >> > > dory.
>> >> >> > > This
>> >> >> > > saves a lot of set up time as I just use any smooth piece of
>> >> >> > > ground
>> >> >> > > instead
>> >> >> > > of a table. This means working on the ground, which has lead to
>> >> >> > > some
>> >> >> > > aching
>> >> >> > > hamstrings, but I am adapting and my assistants (all Thais)
>> >> >> > > don't
>> >> >> > > understand
>> >> >> > > why my hamstrings hurt.
>> >> >> > >
>> >> >> > > 3. Given my experience to date with the film I don't expect any
>> >> >> > > problems
>> >> >> > > with wide panels.
>> >> >> > >
>> >> >> > > 4. The nylon I have used as peel ply is allowing lumps of resing
>> >> >> > > to
>> >> >> > > remain
>> >> >> > > in the panels. This is partly because the resin I have used so
>> >> >> > > far
>> >> >> > > sets too
>> >> >> > > quick in the Thai weather, which is usually well above 80
>> >> >> > > fahrenheit.
>> >> >> > > I have
>> >> >> > > located a supplier 1000 kilometers from here (ATOL) who say they
>> >> >> > > can
>> >> >> > > solve
>> >> >> > > that problem.
>> >> >> > >
>> >> >> > > 5. I will try using only the cling film for most of the panel
>> >> >> > > (except
>> >> >> > > where
>> >> >> > > the vaccum hose goes). This will allow me to see lumps and press
>> >> >> > > them
>> >> >> > > out
>> >> >> > > when I have more pot life. It will mean the cling film won't
>> >> >> > > come
>> >> >> > > off,
>> >> >> > > but
>> >> >> > > as I will paint the hull, a light sanding prior painting (which
>> >> >> > > would
>> >> >> > > be
>> >> >> > > necessary anyway) will remove it (I hope).
>> >> >> > >
>> >> >> > > I am very happy with the clingfilm and think it solves lots of
>> >> >> > > problems.
>> >> >> > > Also, I don't see any reason to bother with a table.
>> >> >> > >
>> >> >> > > Best regards
>> >> >> > > Herb
>> >> >> > >
>> >> >> > > --- In harryproa@yahoogroups.com.au, Rob Denney <harryproa@>
>> >> >> > > wrote:
>> >> >> > >>
>> >> >> > >> G'day,
>> >> >> > >>
>> >> >> > >> You will not save much by bagging the small panels
>> >> >> > >> individually.
>> >> >> > >> This
>> >> >> > >> is what blew the budget on Sol 1. It is quicker to nest them on
>> >> >> > >> a
>> >> >> > >> big
>> >> >> > >> sheet and cut them out afterwards.
>> >> >> > >>
>> >> >> > >> Wet laminating and bagging both sides in one hit is much
>> >> >> > >> quicker
>> >> >> > >> than
>> >> >> > >> setting up for infusion. Sealing the bag is time consuming, but
>> >> >> > >> good
>> >> >> > >> preparation and practice speeds it up, as does good tacky tape
>> >> >> > >> and
>> >> >> > >> a
>> >> >> > >> hole free bag.
>> >> >> > >>
>> >> >> > >> Tape down one long edge of the bag before you start wetting
>> >> >> > >> out,
>> >> >> > >> apply
>> >> >> > >> the tacky tape to the other edges and roll the bag and cover it
>> >> >> > >> to
>> >> >> > >> keep it out of harm's way. Run a piece of tape over the area to
>> >> >> > >> be
>> >> >> > >> sealed to so that resin cannot get onto it. Put the cloth on
>> >> >> > >> the
>> >> >> > >> table and have the drilled core, inner skin and vac stack all
>> >> >> > >> ready
>> >> >> > >> to
>> >> >> > >> go. Wet out the outer skin with a fluffy roller/, spread any
>> >> >> > >> wet
>> >> >> > >> areas with a squeegee. No need to be too careful. Wet out the
>> >> >> > >> core
>> >> >> > >> with a squeegee. Put the core in place and the next layer of
>> >> >> > >> glass
>> >> >> > >> on
>> >> >> > >> it. Wet it out with the fluffy roller. Remove the protective
>> >> >> > >> tape
>> >> >> > >> and apply the vac stack. The trick to long layup times is to
>> >> >> > >> spread
>> >> >> > >> the resin quickly. Leaving it in the pot is a disaster. An
>> >> >> > >> assistant
>> >> >> > >> to measure and mix resin is a good plan, as is premeasuring the
>> >> >> > >> resin
>> >> >> > >> and hardner so they only have to be mixed and stirred.
>> >> >> > >>
>> >> >> > >> Use the amount of resin in the absorber material (I use old
>> >> >> > >> carpet,
>> >> >> > >> costs nothing) as a guide to how much resin you need to apply
>> >> >> > >> next
>> >> >> > >> time. If it goes off too quickly, use slower resin, then throw
>> >> >> > >> a
>> >> >> > >> tarp over the vac bag with a couple of blower heaters
>> >> >> > >> underneath
>> >> >> > >> to
>> >> >> > >> speed it up.
>> >> >> > >>
>> >> >> > >> Fitting out and finish are the difference between boats I build
>> >> >> > >> and
>> >> >> > >> those built by professionals and proud owner builders. Your
>> >> >> > >> shell
>> >> >> > >> will take longer than mine as it is more complex, and you are
>> >> >> > >> learning what you can and can't get away with. My interior will
>> >> >> > >> be
>> >> >> > >> bare, to start with, the decks and beam tops will have non slip
>> >> >> > >> on
>> >> >> > >> them, the bottom antifouling, and the rest will be bare resin,
>> >> >> > >> at
>> >> >> > >> least for the first few months. Partly to show off what can be
>> >> >> > >> done
>> >> >> > >> off the table, partly so I can make any adjustments that become
>> >> >> > >> necessary. Suggest you get a breakdown of hours and materials
>> >> >> > >> and
>> >> >> > >> see
>> >> >> > >> how they compare. It is very difficult for builders to quote
>> >> >> > >> using
>> >> >> > >> a new build system, so the more it is broken down, the easier
>> >> >> > >> it
>> >> >> > >> is
>> >> >> > >> to
>> >> >> > >> fine tune the quote.
>> >> >> > >>
>> >> >> > >> regards,
>> >> >> > >> rob
>> >> >> > >>
>> >> >> > >
>> >> >> > >
>> >> >> >
>> >> >>
>> >> >
>> >> >
>> >>
>> >
>> >
>
>

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