Nautilus Drydocks ALVIN (3D printed)

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  • gboxwood
    Lieutenant
    • Nov 2023
    • 77

    #16
    I'm done with the printing and this is a big relief... I will post pictures of all the parts during the weekend.

    Question about the drive for this build: this is how I envision it, is this a correct assumption?

    ALVIN-007 by Giacomo Bosso, su Flickr

    The propeller is 120mm in diameter, 5 blades from Raboesch, M5 threaded connection to the main shaft (which I then envision to be 5mm DIA).

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    • He Who Shall Not Be Named
      Moderator
      • Aug 2008
      • 12195

      #17
      Originally posted by gboxwood
      I'm done with the printing and this is a big relief... I will post pictures of all the parts during the weekend.

      Question about the drive for this build: this is how I envision it, is this a correct assumption?

      ALVIN-007 by Giacomo Bosso, su Flickr

      The propeller is 120mm in diameter, 5 blades from Raboesch, M5 threaded connection to the main shaft (which I then envision to be 5mm DIA).
      You need a seal at the 'short shaft' to keep water out of the cylinder.


      Click image for larger version

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      Who is John Galt?

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      • Subculture
        Admiral
        • Feb 2009
        • 2114

        #18
        What you have will work, but It'll run smoother if you run a dog bone at each end (constant velocity).

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        • He Who Shall Not Be Named
          Moderator
          • Aug 2008
          • 12195

          #19
          You also need an ahead and astern thrust bearing at the base of the propeller hub.
          Who is John Galt?

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          • gboxwood
            Lieutenant
            • Nov 2023
            • 77

            #20
            Printing completed, here is the layout of the parts:

            Senza titolo by Giacomo Bosso, su Flickr

            Senza titolo by Giacomo Bosso, su Flickr

            Senza titolo by Giacomo Bosso, su Flickr

            Senza titolo by Giacomo Bosso, su Flickr

            And the summary of this printing effort:

            ALVIN-008 by Giacomo Bosso, su Flickr

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            • gboxwood
              Lieutenant
              • Nov 2023
              • 77

              #21
              The lower hull parts are joined first, I start the post-processing by sanding parts with a coarse sandpaper.

              Senza titolo by Giacomo Bosso, su Flickr

              Then I coat them with the XTC resin by Smooth On, sand them and coat them one final time. Below the first coat of resin:

              Senza titolo by Giacomo Bosso, su Flickr

              I will reinforce the joints with fiberglass in the process.

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              • gboxwood
                Lieutenant
                • Nov 2023
                • 77

                #22
                I tried a very quick video to show the parts, I'm no YT personality and I never do it but I thought it could be quicker this way.

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                • Subculture
                  Admiral
                  • Feb 2009
                  • 2114

                  #23
                  Looking good. Wonder why those files don't have the lower viewing port- makes a useful potential vent for the lower hull if you leave the port unglazed.

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                  • gboxwood
                    Lieutenant
                    • Nov 2023
                    • 77

                    #24
                    Originally posted by Subculture
                    Looking good. Wonder why those files don't have the lower viewing port- makes a useful potential vent for the lower hull if you leave the port unglazed.
                    Yes I noticed it myself this morning as I was working on it...

                    Comment

                    • Subculture
                      Admiral
                      • Feb 2009
                      • 2114

                      #25
                      Perhaps that port was removed at some point in its evolution. It's certainly had at least one change of pressure sphere in its long lifespan which changed the layout of the ports amongst other changes.

                      Comment

                      • gboxwood
                        Lieutenant
                        • Nov 2023
                        • 77

                        #26
                        I spent some time with the lower hull today, sanding the first resin coat smooth:

                        Senza titolo by Giacomo Bosso, su Flickr

                        Senza titolo by Giacomo Bosso, su Flickr

                        The white spots in the resin mean you sanded all the way back to the plastic. This is why I typically use more than one coat.

                        Senza titolo by Giacomo Bosso, su Flickr

                        I also added 4x 30mm draining holes following what Bob did on his model (according to the YT video).

                        The joint are reinforced with a layer of 110 grams fiberglass cloth. I do this on top of the first coat of XTC resin because the XTC sticks to the plastic incredibly well and probably better than any other laminating resin.

                        Senza titolo by Giacomo Bosso, su Flickr

                        This will be sanded smooth once cured and then coated with XTC one final time.
                        Last edited by gboxwood; 12-04-2023, 03:35 AM.

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                        • Alucard
                          Lieutenant Commander
                          • Aug 2023
                          • 101

                          #27
                          Great job, good information.

                          Comment

                          • gboxwood
                            Lieutenant
                            • Nov 2023
                            • 77

                            #28
                            Thank you!

                            One thing I always try to do is "de-feature" the STL files to the extent that it makes printing easier and/or more efficient.

                            For that purpose, I use the Meshmixer software which is a pain to work with and at which I'm not very good at. However, some times it is easy, like in the example below.

                            It does not make a lot of sense to print the front hook together with the lower hull, this detail can be rendered much better if printed as a separate part and added later.

                            So, I removed the one I printed with the hull...

                            Senza titolo by Giacomo Bosso, su Flickr

                            Senza titolo by Giacomo Bosso, su Flickr

                            ... and I then separated the two parts in Meshmixer:

                            ALVIN-009 by Giacomo Bosso, su Flickr

                            ALVIN-010 by Giacomo Bosso, su Flickr

                            Then I can print the hook separately and use real screws to attach it to the hull for added realism and scale detailing.

                            ALVIN-011 by Giacomo Bosso, su Flickr

                            Comment

                            • gboxwood
                              Lieutenant
                              • Nov 2023
                              • 77

                              #29
                              Hi Guys, I started thinking about the dive system for this application and I would like to pitch it here for your feedback.
                              I'm thinking simple here and maybe it will be too simple but let's give it a try...

                              Now, in the following diagrams, RED means CLOSED/NOT RUNNING and GREEN means OPEN/RUNNING.
                              Also, the ballast tank only is shown.

                              These are the states I envision at the moment.

                              ALVIN-012 by Giacomo Bosso, su Flickr

                              1. Surface trim
                              - snorkel solenoid closed (normally closed)
                              - pump not running

                              2. Diving
                              - snorkel solenoid open
                              - pump runs and fills the ballast tank with water

                              3. Submerged trim
                              - snorkel solenoid closed (normally closed)
                              - pump not running

                              4. Surfacing (below snorkel depth)
                              - snorkel solenoid open
                              - pump runs and empties the ballast
                              * the snorkel diameter shall be chosen so that it is way smaller than the tank in/out line diameter
                              * this way, the snorkel will let in some water but less than what the pump pushes out... until a balance is reached
                              * hopefully, when that balance is achieved it will be enough to raise the snorkel above water
                              * testing will confirm the above scenario

                              5. Surfacing (above snorkel depth)
                              - snorkel solenoid open
                              - pump runs and empties the ballast​

                              6. Emergency surfacing
                              - a completely independent system opens a valve that releases compressed air into the tank
                              - an equally independent valve should open as well in order to let the water out of the tank form a different route than the pump in/out line

                              Does any of this make sense?

                              Thank you in advance!​

                              Comment

                              • RCSubGuy
                                Welcome to my underwater realm!
                                • Aug 2009
                                • 1762

                                #30
                                A pump, three separate solenoid valves and a pressure vessel? Why are you making this so complicated?

                                Alvin needs next to no positive buoyancy. You want a precision systems such as a piston or water pump (I'd go the pump route as you outlined). Just have a sealed tank, a geared pump and one solenoid. Wire the solenoid and pump in parallel so the solenoid opens with pump power. This is an Eden/Sheerline/OTW style system that is simple, reliable and very precise.

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