CB italian midget sub : lining up the hull halves

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  • raalst
    Senior Member
    • Feb 2003
    • 1229

    #1

    CB italian midget sub : lining up the hull halves

    My project this winter (and summer and winter and...)
    is a Caproni type CB italian midget submarine.
    Why this one ? well, it's cute...
    The CB looks like this :


    there are two left in this world, one in the technical museum of Zagreb
    and one in a museum in Trieste.
    I plan to visit one of the two, because there is not too much photo's
    around on the 'Net.

    it is my first scratch build, and it will progress slowly.

    I am building from plans by ANB, which proved difficult to obtain.
    the link to ANB is http://www.anb-online.org/page_info....roducts_id=942
    but their online shop is not operational.
    If you need to contact them in the future, I might be able to help.
    their plans are nice.

    I had the plans copied and 30% reduced so the model will be about
    1m40. It amounts to a scale of 1]http://home.vianetworks.nl/~raalst/cb/cb001.jpg[/img]
    I bought a motorized saw just for this job. cutting about 64 ribs
    by hand is not my idea of a hobby.


    both ribs were then positioned using a 1cm MDF "side view".
    I glued copies of the plan to the MDF and cut out the profile.


    The ribs were spaced and held by M5 threaded rod. So I had the
    profile, and the left and right set of ribs.
    Then I drilled holes thru the profile, just aboove and below where
    the rods are, and tied the halves together with tiewraps, clamping the
    side view profile inbetween. The rod was just flexible enough to align
    the ribs with some precision.


    I used polyurethane foam to fill up the spaces and make a solid
    plug. polyurethane foam is polyester resistant, and I did not have to
    find foam plates of the proper thickness.
    I tried on a test-rig first.

    It turned out quite nice, but the foam had bent the ribs about a
    millimeter outwards.

    the foam remains rather soft, but I plan to apply a hard shell
    by means of polyurethane yacht varnish.

    when foaming the plug, I made sure to
    foam the outer ribs first, and work towards the middle ribs
    It's impressive stuff, that foam. I made a makeshift
    dam to keep the foam where I needed it.


    then some crude sawing, cutting and coarse sanding, and it came out
    like this ]http://home.vianetworks.nl/~raalst/cb/foam3.jpg[/img]

    using a third bottle of foam, after filling the remaining gaps
    the current result is

    A nice side-effect of the foam is that it also glues the ribs to the profile.

    Next steps are filing and sanding the MDF ribs exact,
    then plastering, then varnish, then plastering with polyester.
    after that the scary stuff begins (i.e. moldmaking).
  • Guest

    #2
    One tip I'd suggest is

    One tip I'd suggest is covering the master with a layer of fibreglass matt and resin. Polyester filler isn't very flexible or strong and dents easily.

    A layer of glass and resin will make the plug very strong indeed.

    Andy

    Comment

    • bigdave
      Junior Member
      • Feb 2003
      • 3596

      #3
      A good friend of mine

      A good friend of mine is building the same sub. I always call it the TOON sub. As it looks like it was designed by the Tiny Toons! It's so cute!! BD.
      sigpic"Eat your pudding Mr Land"
      "I ain't sure it's pudden" 20K

      Comment

      • raalst
        Senior Member
        • Feb 2003
        • 1229

        #4
        @bigdave

        I think I know

        @bigdave

        I think I know your friend. He helped me obtain the ANB plans.

        BTW, my contact in Italy informed me that
        the ANB plans can now be ordered via the italian
        business called MagicModel,
        www.magicmodel-online.it
        info (at) magicmodel-online.it

        This shop is run by the secretary of the ANB, or so I understand.

        I have the postal details if required.

        Comment

        • bigdave
          Junior Member
          • Feb 2003
          • 3596

          #5
          Hi Ronald,
          Yes we do

          Hi Ronald,
          Yes we do indeed have the same friend. Best of luck on your project! That is such a cool and unusual boat. BD.
          sigpic"Eat your pudding Mr Land"
          "I ain't sure it's pudden" 20K

          Comment

          • JWLaRue
            Managing Editor, SubCommittee Report
            • Aug 1994
            • 4281

            #6
            Maybe this will encourage our

            Maybe this will encourage our mutual friend to get more progress done with his.

            He's been talking about it for several years now!

            -Jeff
            Rohr 1.....Los!

            Comment

            • PaulC
              Administrator
              • Feb 2003
              • 1542

              #7
              Jeff,

              What is "our mutual friends"

              Jeff,

              What is "our mutual friends" current email address? I wanted to drop him a note regarding the article on his boat in the latest SCR.
              Warm regards,

              Paul Crozier
              <><

              Comment

              • JWLaRue
                Managing Editor, SubCommittee Report
                • Aug 1994
                • 4281

                #8
                Hi Paul,

                E-mail inbound.......

                -Jeff

                Hi Paul,

                E-mail inbound.......

                -Jeff
                Rohr 1.....Los!

                Comment

                • colin-stevens
                  Junior Member
                  • May 2006
                  • 10

                  #9
                  looks like a real beut,

                  looks like a real beut, may look into it myself.
                  keep up the good work
                  colin

                  Comment

                  • raalst
                    Senior Member
                    • Feb 2003
                    • 1229

                    #10
                    the plug is now covered

                    the plug is now covered with gypsum (plastercast ?).



                    the gypsum will enable me to smooth the surface to a degree.
                    the lower part is already sanded, now the upper part must be
                    sanded.
                    After that, some polyester coating will be applied and then the
                    finer smoothing starts.

                    I practiced my first glassing today on another project. seems
                    not to involve rocket science. Might be beginners luck though

                    Comment

                    • raalst
                      Senior Member
                      • Feb 2003
                      • 1229

                      #11
                      today the tower was shaped.

                      today the tower was shaped.

                      I love polyurethaanfoam

                      base shape.



                      nothing is level...




                      the plastic strip is a nice indicator of where to sand.


                      Comment

                      • Guest

                        #12
                        Going well.

                        You're doing things in

                        Going well.

                        You're doing things in the reverse order to my way of working though.

                        I skin the foam with glass and resin, then use polyester filler and glazing putty for the final finish. I don't like using plaster- tried it before and found it lacking in strength, plus it takes a while to fully harden off.

                        However you're method will work, but I'd skin it with resin and glass at the nearest opportunity, as the finish will be very vulnerable up until that point.

                        Andy

                        Comment

                        • raalst
                          Senior Member
                          • Feb 2003
                          • 1229

                          #13
                          Andy,

                          that is the plan. especially

                          Andy,

                          that is the plan. especially after reading Mylo's story.

                          the trade off I made is that I rather work with non-toxic
                          stuff.

                          After the next sanding I will glass the hull and continue with
                          polyester filler.
                          That also means I am banned to the (unheated) shed, as I cannot
                          safely sand polyester filler inhouse.

                          The plaster hopefully makes that there is not too much polyester filling
                          to be done.

                          Comment

                          • raalst
                            Senior Member
                            • Feb 2003
                            • 1229

                            #14
                            applying the polyester went wrong

                            applying the polyester went wrong on the first side I glassed.



                            let's see how the other side will come out...

                            Comment

                            • anonymous

                              #15
                              I really like your choice

                              I really like your choice of subject matter here Raalst. Nice to see you scratch build. I will be watching.

                              Keep going!

                              steve

                              Comment

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