I think polycore is polypropylene,which usually melts around 160C, to
get it bendable maybe 120-140 C?

--- In harryproa@..., "Rob Denney" <harryproa@...> wrote:
>
> G'day,
>
> On Wed, Jul 2, 2008 at 2:03 PM, Robert <cateran1949@...> wrote:
> >
> > G'day Rob,
> > -To give you someone else to swear at for stating the obvious with
> > 20/20 hindsight from my armchair.
> > Extra bog or extra glass to avoid the centre V.
>
> Would need to be quite a bit of extra glass (basalt, actually) as it
> is only 200 gsm. Bog may have done it, but it introduces another
> variable.
>
> >
> > Can't see that a
> > shallow V is a problem
>
> It's not, but the middle 50% of the boat is glassed all the way across
> and only the middle 25% has the join, so the section is a V between
> two semi circles, which is. It was also not very shallow.
>
> > What was the ambient temperature during this run compared to the
> > previous? A blow heater through the guts may help. Possibly some thin
> > cheap ply on the outside and inside to keep the bending more even
>
> 20C. Some heat may help, I will try it tomorrow when I bend this one.
> I am also using 4mm Polycore for the 3m hull instead of 6mm.
> >
> > To avoid stretch when squashing, a long as possible heat conductive
> > piece of stiff flat metal-possibly box section insulated on three
> > sides, so that you can blow heat down the middle. It then gets pressed
> > all at once rather than squashing it little by little- the process
> > used in spinning and beating metals.
>
> Needs to be seriously hot. I had the wife's clothes iron on full heat
> and even then it was not a quick operation. Bog on the edges works
> (but not if it is vacuumed) or it would not be too difficult to make a
> bog bevel. On the bigger boats, could put a roll of uni or tow along
> the edge to make the step.
>
> > No need to make any comments about slopping resin where it is not
> > needed;>(
>
> Bloody stupid sums it up pretty well.
>
> > Thanks for making the mistakes so we don't have to make as many
>
> My pleasure.
>
> regards,
>
> Rob
> > Robert
> >
> > -- In harryproa@..., "Rob Denney" <harryproa@> wrote:
> > >
> > > G'day,
> > >
> > > Folded up the ww harriette hull today. Did not go well. Mostly
> > because I
> > > rushed it. The centre piece folded beautifully, although it took a
> > bit more
> > > effort than I thought it would. I was concentrating on the
middle and
> > > thought the ends would be following suit. They weren't. The
> > Polycore did
> > > not bend evenly on either side iof the centreline, resulting in a
> > mess. At
> > > one end this was caused by some spilt resin stiffening one side more
> > than
> > > the other, but at the other it just bent crooked, which is a worry.
> > >
> > > The centre section had a fore and aft join along the middle
(trying to
> > > minimise material use) which bent as a V instead of a semicircle
> > like the
> > > rest of it. I also tried ironing the Polycore to taper the edges,
> > as per
> > > the NidaPlast site. It worked, but stretched the material on the
> > underside
> > > so it ended up as a wavy edge which needed to be filled. This had
> > not shown
> > > up on the short pieces I had experimented on.
> > >
> > > Bit disappointing, but the lessons learnt are:
> > > 1) Keep resin off unglassed areas
> > > 2) No fore and aft joins in areas to be bent
> > > 3) Lock the centreline to the table before bending. I used a long
> > straight
> > > edge clamoped to the table for the experiments, completely forgot
> > this time.
> > > 4) Slow bending is even bending. I suspect foam would bend more
> > uniformly,
> > > but would have to be even slower to stop it breaking.
> > >
> > > So, some serious abuse of me by me, some stroppy responses to
> > various forums
> > > (better pressure relief valve than kicking the cat or shouting at
> > the wife
> > > and kid) and I am trying again today.
> > >
> > > regards,
> > >
> > > Rob
> > >
> >
> >
>