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Author Topic: Carving foam hulls  (Read 2255 times)

wsnowdon

  • Guest
Carving foam hulls
« on: June 21, 2005, 05:21:57 AM »
Right, heres a method I have used succesfully. 1.Cut out the deck
and keel shapes from ply or thick card. Stick deck onto keel as per
normal model construction. (this gives a strong template to cut to).
2. If you have an electric bread or carving knife, it is perfect for
rough shaping and Very quick. 3. use foam in layers, bread and butter
fashion lightly tacking to deck and keel with small blobs of PVA, as
after innitial shaping they need to be separated. Join foam layers
with dowels or kebab sticks with glue on to firmly but temporarily
hold layers together. 4. Carve to shape with electric knife if you
have one or an old facshioned bread knife. Sand to final shape. 5 .
Now for the clever bit! Separate layers of foam and cut out
machinery, radio, ballast spaces etc then firmly glue back together
with waterproof PVA glue. you now have an ubsinkable hull. Replace
card deck and keel with permanent deck and keel. 6. When satisfied
with shape, cover entire hull with two layers of model aircraft
tissue stuck on withPVA. This gives a good foundation for your final
finsh. 7. Add card or thin ply bulwarks. Now its choice time. Either
cover entire hull and bulwarks with glass cloth and resin (take care
it doesnt get onto bare foam) or plate in card or gum strip to
simulate plating. If you opt for a fibreglass hull, you can pour
thinners into the hull and the foam dissapeers like magic leeving a
hollow FG hull with a very thin hard plastic coating inside. The
thinners evaporate away. Sorry this is a bit long, Ive cut it to the
bare bones, so if you have any queries please ask. All the best
Walter.

Paulrjordan

  • Guest
Carving foam hulls
« Reply #1 on: June 21, 2005, 05:22:24 AM »
Excellent, Walter...a very useful process and a couple of little
tricks I wasn't aware of. Mind you, one question I have.

Given you have templates for deck and midships profile, how do you
achieve correct bow flair, bilge and stern shape? You didn't mention
if you use the cross sections (frames) too if they happen to be
available. If they are, do you use them in any way to give you the
correct outside hull curves (maybe as outside templates?) and to
achieve the final shape...or do you have some other trick?

and from your companion post:

--- In Paddleducks@yahoogroups.com, "walter (alias Talisman)"
<w.snowdon@n...> wrote:
> Sorry, I forgot to mention, use blue or pink foam as this is far
> and away the best as it is very dense and carves easily with sharp
> edges.

> White foam is poor as it is made from beads which collapse as you
> cut it. Florists foam is too powdery and colapses into dust if you
> put any pressure on it.

Yes I totally agree and just have a little bit of added comment on
the blue and pink which I have had the most success with.

Pink is lighter in weight (the aircraft guys favour it) but a little
more brittle and more likely to crack. Blue is more pliable not so
prone to cracking. In fact if you take blue and slice a 1/8" strip
and run it between your forefinger and thumb, you wouldn't believe
how pliable it becomes and can bew very useful as a "skin" over
ribs. I know of a modeler in our club who builds fabulous models
this way out of meat tray foam!

Thanks again for all the input Walter, it really helps in developing
a body of knowledge which PD modelers may have fun experimenting with.

Regards

PJ
Victoria, BC Canada

wsnowdon

  • Guest
Carving foam hulls
« Reply #2 on: June 21, 2005, 05:22:48 AM »
Evening PJ. Sorry for the ommission. If you have hull frame shapes,
Mark their positions on the temporary deck and keel. Use OUTSIDE
formers/templates (for the ininitiated, these are the bits os shapes
you would cut off if you were cutting hull ribs out). Rough carve the
hull and finish by sanding until the templates touch the deck and
keel fitting evenly around the hull. Do this for each frame position
on both sides of hull, If you have no frame shapes, get as many
pictures of the full hull (or a similiar hull) cutting
and "eyeballing" the shape of the hull. It is suprising how accurate
this can be. For those interested, long before the advent of plastic
kits, I used to build 1/72 scale aircraft models using this method!
My brother and I built in excess of 100 planes using this method
before we got our first plastic kit! our carved models were far more
accurate ! Cheers for now, Walter.

wsnowdon

  • Guest
Carving foam hulls
« Reply #3 on: June 21, 2005, 05:23:13 AM »
Sorry, I forgot to mention, use blue or pink foam as this is far and
away the best as it is very dense and carves easily with sharp edges.
White foam is poor as it is made from beads which collapse as you
cut it. Florists foam is too powdery and colapses into dust if you
put any pressure on it. Builders yards are best for blue and pink
foam or your local model aircraft club will use scads of it for
carving aircraft fuselages or will know of loal suppliers. Cheers,
Walter.

TEX

  • Guest
Carving foam hulls
« Reply #4 on: June 21, 2005, 05:23:38 AM »
I'd like to suggest Hot Wire Cutters. There are sand casting
hobbiests that are usin the same foam you speak of, to make patterns
for hot metal castings. It's referred to as Lost Foam Casting. These
hot wire cutters are usually homemade and look much like scroll
saw. In lieu of a blade, they use nichrome wire. The voltage is
applied with various types of transformers, but a large model train
transformer seems to be the choice in that it gives you variable
heats. It's nothing more than a spring loaded, pivoting upper arm
with a fixed arm beneath the cutting surface. If anyone is
interested, I sure I can borrow some photos and maybe some diagrams
of how they make em.

Foam wings for RC planes has been around since the mid to late 60's.
I don't know of any that use foam fuselages, but I'm not saying
there isn't. They are cut with hot wire cutters. When necessary,
they embed spars in the core to beef up the wings. Then they are
covered with an opaque plastic film (MonoKote) then heat shrunk
using heat guns or tacking irons. They are water and fuel proof.
MonoKote comes in a variety of colors. ... :o) TEX

 

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