-I have been thinking of that also. Whatever you do will make some
kind of discontinuity. I would simply butt them up possibly with hot
glue providing you have a close fit and glass them . Other
possibilities is to iron a chamfer to opposite sides and overlap with
a little resin in the middle, but this would make a slightly stiff
line. You could fill in with microballoons but this would also leave a
stiff section. You could put a very thin tape glass tape over the
edges to add just a little stiffness and avoid filling the cut
honeycomb with epoxy when you bag it.
I can see your concern with the thought of water moving sideways
through the core. I am going with honeycomb as it shows the best
characteristics under collision and it is a good price. I also have
some trepidation about using PVC as it is a fairly noxious material
long term when burned and is difficult to dispose of. Polyprop is much
less noxious long term but would not want to be too close to it if it
did burn. There are different grades of polyprop and if the membranes
were properly welded I can't see any major problems. It will weaken
under high temperature and if then suddenly exposed to cold water
shock I imagine could induce microscopic tears. Tests have shown it is
less susceptible to catastrophic failure
It is pretty hard to stick anything to it without welding so I would
like to make sure any through bond was attached securely to the back
skin. I can't see how you can get a good stick to the inside unless
you melted in solid polyprop. I would be more tempted to go to the
back side and iron the area to flat at the centre and gradually
increasing to the full thickness at the outer edge. This would well
seal the edges of the honeycomb without any problems of not sticking
-- In harryproa@yahoogrou
>
> Hi,
> I am also drifting a little from the topic, but how do you join full
sheets
> of honeycomb when making a big panel? Do you route out the edges and
epoxy
> in a foam strip? Or something else?
>
> - Gardner
>
> On Thu, Feb 5, 2009 at 8:38 AM, Mike Crawford <jmichael@..
>
> >
> > Oh, and while this may be redundant for most on the group, I
thought I'd
> > add a comment on sealing techniques for anyone who hasn't been
using them.
> >
> > There are two that we (and our boatyard) use, depending upon the
size of
> > the penetration:
> >
> > a) For small holes, overdrill the hole size, fill the hold with
thickened
> > epoxy, let it cure, and then drill the proper hole through the
center of the
> > solid expoxy section.
> >
> > b) For larger holes, drill out the proper sized hold, then use a
router
> > with a bit that fits in between the skins to rout out 6mm of core
material,
> > fill with thickened epoxy, and let it cure.
> >
> > It's also possible to use a hybrid method on larger holds for extra
> > security.
> >
> > - Mike
> >
> >
> >
> > Gardner Pomper wrote:
> >
> > Hi,
> >
> > I don't know if anyone is watching the KSS forums, but I got Derek to
> > give a little more detail on the test he did where he sees water
> > infiltration into honeycomb. It was a sample with unsealed edges,
put in
> > boiling water for a minute, the doused in cold (not ice) water. He
> > immediately got water in 3/4 of the cells. He let it sit for a
day, by which
> > time all except 3-4 cells had water in them, meaning that water
migrated
> > between cells even after cooling.
> >
> > This seems to be a test of what would happen if the skin was
broken, or
> > some cut (cleats, hatches, etc) was not sealed completely. If
water does
> > migrate in honeycomb, might we be better to restrict its use to
the hull
> > sides and maybe the bridgedeck, which does not get as much water
exposure or
> > hardware mounting?
> >
> > Derek didn't specify a manufacturer he tested. I have a sample of
> > Nidacore I am going to try this on. Maybe we could see if it is
true of all
> > the different varieties.
> >
> > Any thoughts? Is this serious or just a reason to be extra careful
> > sealing holes in the honeycomb?
> >
> > Thanks,
> >
> > - Gardner Pomper
> > York, PA
> >
> >
> >
>
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