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CB italian midget sub : lining up the hull halves

This is the place to post your submarine build- ups.

Postby raalst » Sun Feb 03, 2008 6:44 am

The casing for the first half of the mold is ready.
I also sealed the gap between boat and board with
paraffin wax.

Image

after the silicone rubber layer I will apply a layer of plaster,
and then the rest of the casing is filled with PU foam.
This will be leveled to the top of the casing, and the casing sealed with
another board. Then the whole is put upside down, and I should have
a mold half in a box with a fixed plaster interior, and a
removable silicone rubber inner mold
Regards,

Ronald van Aalst

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Postby raalst » Sat Feb 09, 2008 4:16 pm

the first layer of rubber has been applied. finally...

Does anybody have a good tip (from his/her *own* experience)
for a filler material in the silicone rubber ?
a filler material means more volume for less bucks, hopefully.
Regards,

Ronald van Aalst

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Postby U812 » Sat Feb 09, 2008 4:47 pm

Not really and filler can make the RTV weak. Generally I brush layers on. Up to about 3/16 of an inch thick making sure I keep the out side of the RTV as smooth as possible. Once you make your mother mold it will be well supported. If it's a good RTV that's all the thickness you'll need. Anymore is a waste. Just take your time. The mold is everything.

Steve

P.S. If you plam to use plaster be careful. It is a weak and heavy material. Back it up with burlap. first do a splash layer. Then follow up with burlap and plaster. Another coat with just plaster. Lighter and stronger. Best is to make an epoxy glass mother mold if you can.
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Postby raalst » Sat Feb 09, 2008 5:18 pm

Thanks for the tips !
I *will* reinforce the plaster shell.

I agree epoxy is lighter/stronger but I am a bit scared about
- exact ratio's of stuff and catalyst required
- toxicity
And polyester might shrink/warp too much and distort the
RTV mold.
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Ronald van Aalst

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Postby U812 » Sat Feb 09, 2008 5:42 pm

You bet Ronald. Like I said. Take your time. You put a lot of good work into that hull and you don't see a model of this subject everyday!

Best of luck,

Steve
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Postby raalst » Sun Feb 10, 2008 7:53 am

here is a picture of the second layer of silicone rubber.
Note I colored the second layer so I could see what was
covered and what was not.
third layer will be white again.

Image
Regards,

Ronald van Aalst

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Postby Sub culture » Sun Feb 10, 2008 8:16 am

A polyester resin hardcase will work okay. Shrinkage is negligable- if it was that bad, you wouldn't be able to cast a hull from it (think about it)

Andy
'Why are you staring at an empty pond?'

Want to dive your boat in crystal clear water? Then you had better Dive-in- http://www.diveintomodelsubmarines.co.uk
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Postby raalst » Sun Feb 10, 2008 9:15 am

I'm considering GRP.
(Glass Reinforced Plaster) ;-)
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Ronald van Aalst

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Postby Paul » Tue Mar 18, 2008 4:21 pm

Your sub is looking great. Can't wait to see it finished.
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Postby raalst » Tue Mar 18, 2008 5:48 pm

Thanks Paul ! Me too...

almost finished with the silicone for the first half now...
Even having two hull halves per the 18th of May seems ambitious now.
(18th is our local dutch yearly sub event)
Regards,

Ronald van Aalst

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Postby raalst » Sat Mar 22, 2008 1:27 pm

Next Phase ! plaster time ahead.

as you can see the silicone is rather lumpy, this is because I re-used
small shreds of old cured RTV in the middle layers. Because of
this, I think I can leave the registration bumps out of it.

I must confess 2 cockups :

*always* plan before you drill a hole
Image

*always* plan before you saw a hole in a plank. The little built-up
of the boat is now crammed into a cut-out recess in the planking.
Otherwise the plank could not be attached full-length to the board..
Image

My late grandfather would have been disappointed. He teached me
woodworking far better than this...
Regards,

Ronald van Aalst

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Postby raalst » Mon Mar 24, 2008 8:52 am

plaster is being applied. I found a synthetic wool sold in pet shops
(it is called filter wool and intended for aquariums) and used that
as "rebar" for the plaster instead of burlap.

first impressions about it are good. but of course all shall be revealed
then the box is turned and the original removed.

Image
Regards,

Ronald van Aalst

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Postby raalst » Mon Mar 24, 2008 11:56 am

Compared to this, the egyptian kings sleep their eternal sleep in
cardboard boxes :)

Image

btw, what is this metal wire stuff called in english ? over here it is
called kippengaas (hen's mesh)...
Regards,

Ronald van Aalst

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Postby Pirate » Mon Mar 24, 2008 1:02 pm

Ron,

We call it chicken wire. But won't it rust in the plaster, therefore negating any structural integrity?

As Steve said, burlap or hemp is traditionally used here in the plaster.

Pete
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Postby raalst » Mon Mar 24, 2008 3:43 pm

Hi pete,

no, the chicken wire is galvanized and the plaster is only
wet for a short while.
I had no burlap or hemp around (smoked it all :twisted: ).
Regards,

Ronald van Aalst

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