Thanks for you frank reporting of mistakes/problems as well as
milestones, Rob. Your openness is a blessing to those of us who are
trying to learn...
This is my first post, but for some months I have been sitting down
the back of the class...

Regards,

Jeff

--- In harryproa@..., "Rob Denney" <harryproa@...> wrote:
>
> G'day,
> Can't find it on the Nida web page, but the honeycomb cells are a bit
> lower melting point than the felt scrim. Problem with too much heat,
> if you over heat the cells, the felt melts and there will be no bond.
> I have used bog on the deck and the hull, adds less than half a kg,
> but is a pain to do. Hull came out pretty well, deck is curing at the
> moment. Will bend the hull (slowly!) over the weekend.
>
> regards,
>
> Rob
>
> On Fri, Jul 4, 2008 at 2:15 AM, captian_rapscallion
> <captian_rapscallion@...> wrote:
> > 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
> >> > >
> >> >
> >> >
> >>
> >
> >
>