Assembling a 1/87 USS NAUTILUS kit

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  • He Who Shall Not Be Named
    Moderator
    • Aug 2008
    • 12241

    Assembling a 1/87 USS NAUTILUS kit



    NAUTILUS PART-1

    I first became aware of the model work of Andreas Schmehl a few years back while checking out the articles at one of the few forums dedicated to r/c submarine model building. His work-in-progress (WIP) -- a format of article writing that is heavy on in-progress photos with supporting text -- dealt with the construction of a 1/23 scale, U-1. Germany's first combat submarine. It was the most comprehensive and well laid out WIP I had ever read.

    That multi-part article had everything: CAD design, CNC'd hull masters; 3D printed detail parts; hard-shell, GRP hull tools; RTV rubber tools for the small stuff; GRP lay-up; resin casting; WTC design and manufacture; trimming; detailing; and painting.

    As Andreas put it: "I mainly use CAD to create a virtual model of the hull and the interior technical structure. From that I produce the 3D files for manufacturing 3D-printed parts and for milling preforms for the GRP tooling". What Andreas calls 'preforms' we American's understand these as masters, or patterns.

    Once Andreas had worked out the 'plans' in CAD, he sent the files to a second party fabricator who used them to cut machinable plastic medium via CNC milling machine, and to poop out plastic parts via 3D printer. Those parts, back in Andreas' hands, becoming the masters of off which he would produce the actual model parts.

    Masters by robot. Tooling and model parts by the good doctor.

    SkyNet, call your office!






    His U-1 article showed me, in a very well laid out article, the use of computers and mechanized subtractive and additive item manufacture as part of the model building process.





    Andreas has done the same thing with his current r/c submarine project: a dry-hull 1/87 scale model kit of the famous, USS NAUTILUS.
    His first USS NAUTILUS, assembled from his kit -- as is the European practice -- was configured as a dry-hull type r/c model submarine. With the exception of the sail and a portion of the stern (where the stern plane, rudders and propeller shafts make up to their respective running gear and linkages) the entire hull is dry.



    Another European practice -- most suitable for dry-hull types r/c submarines -- is to access the interior through a set of bayonet rings that seal with an o-ring. Set into the forward and after sections of the model, the bayonet rings produce a radial break between the two. To access the interior all that is required is a slight rotation of the hull halves to free the lugs of the bayonet rings and simply pull the two hull halves apart. A positive, quick, easy and pressure-proof closure method. Attaching the equipment-device mounting structure to the stern exposes everything when the forward section of hull is removed.

    Unlike wet-hull type models -- which require opening the hull through a horizontal equatorial break, removing the WTC, and only then gaining access to the devices by removing the end-caps of that WTC -- the dry-hull bayonet rings make for excellent access to the internals for repair, de-watering, adjustment and maintenance tasks.



    The advantage of the dry-hull is that there is plenty of available volume in which to stick all the propulsion, control, and ballast sub-systems.

    However, as the superstructure and portions of hull above the waterline will displace so much water when they are immersed, it takes a great deal of water weight --- taken into an internal ballast tank -- to create the force needed to counter the buoyant force produced by all that displacing structure. A big ballast tank takes up valuable real-estate within the tight confines of the hull.

    The need for such a large internal ballast tank denotes the major disadvantage of the dry-hull type submarine.





    Andreas followed the same manufacturing methodology with his NAUTILUS kit. A second-party produced the masters from which he would make to tooling needed to create the model parts. Here we see some of the CNC milling-machine cut masters.



    Off those CNC cut masters Andreas laid-up these GRP hard-shell tools. A total of eight tools required to render all the hull and sail parts. Those GRP parts rendered as very thin section structures.
    Who is John Galt?
  • He Who Shall Not Be Named
    Moderator
    • Aug 2008
    • 12241

    #2
    The need for such a large internal ballast tank denotes the major disadvantage of the dry-hull type submarine.





    Andreas followed the same manufacturing methodology with his NAUTILUS kit. A second-party produced the masters from which he would make to tooling needed to create the model parts. Here we see some of the CNC milling-machine cut masters.



    Off those CNC cut masters Andreas laid-up these GRP hard-shell tools. A total of eight tools required to render all the hull and sail parts. Those GRP parts rendered as very thin section structures.



    In addition to the resin and GRP parts he produced from this tooling, Andreas also produced the art work from which he had acid-etched a fret of wonderfully detailed deck, radar antenna reflector, other detail parts ... and even a painting mask needed to produce the white '571' on the sides of the sail.

    Also provided in the kit is a set of water-slide type decals containing the white draft markings for the hull and upper rudder.



    With this picture I'm jumping ahead a bit -- this is Aundrea's initial assembly of his kit. I include it here to point out the use of the very detailed acid-etched deck pieces. Provision is made in the upper GRP hull to accommodate this. A slight step is provided atop the hull to sit this .015" thick acid-etched item atop the hull so that it sits flush. Though the USS NAUTILUS is distinctive of lines, it is a rather boring subject to look at if the details that are there are not exploited to the maximum -- such is the case with the deck: safety-track, slotted wooden deck, deck hatches, marker buoys, cleats, torpedo loading skid, these and more are items captured by the brass metal deck pieces. Even a bridge deck grating is provided on the acid-etched fret.



    Andreas will be making this kit commercially available. What is pictured above is what I would consider to be a more than adequate kit: right down to pages of exploded-view, orthographic and isometric drawings outlining not only assembly of the kit proper, but recommendations for the fabrication and assembly of the European style internals.
    A preliminary kit. What I'm presenting here is likely not the definitive version -- note that there is no bayonet rings to accomplish the water tight radial break between forward and after hull halves; that the hull pieces (five of them) are provided split to suit those wishing to assemble this r/c submarine as either a wet-hull or dry-hull type; and no form of tech-rack (as the dry-hull guys would describe the internals mounting arrangement) or water tight cylinder (WTC) is provided. Also, there may be material changes before the production kits hit the street. So, regard what I've pictured here as a Beta test article, subject to change.



    The resin pieces are of exceptional quality. Right down to the bezels and gyro-repeater that attach to the open bridge!
    The items to the right include the bow plane foundation, anchor well, bow planes (detailed right down to the universal cup joints that make up to the retract/deploy struts), deck sonar faring, anchor, and deck hatches. In the middle we see the mast foundation, open bridge well, sail top with all mast and bridge openings, antenna and snorkel induction items, as well as the scopes and antennas attached to their respective fairings. Items to the left are the two rudders and two stern planes.
    The dark items are cast from epoxy, the lighter items are cast from polyurethane.



    ... And these two little jewels: the NAUTILUS propellers! Brass, no less. However, it is prohibitively expensive to have these propellers cast in brass, so I'm working on Andreas to consider a white-metal alternative -- any heart-burn about that in the future, you can blame me. You do want a kit you can afford, right?....
    It's obvious Andreas did his homework on these. The blades appear to be of a scale thickness -- no small feat! And they are of the right shape. These two wheels are simply gorgeous! Matched with the right motors and gear-train, these propellers should scoot the NAUTILUS along at a very good clip.



    The nominal GRP part thickness is about .050"! In the world of model submarines that is as good as it can get! And the uniformity of the lay-up is even throughout the parts. These two observations point to a fabricator who has been grounding in aircraft quality GRP part fabrication. Which Andrea was. He studied at the feet of an FAI quality contest r/c powered glider fabricator and flyer. The quality of his glass work is a testament to this early training. You can't buy that type of training!

    Note that the hull kit is presented in five pieces. This break-down offers the customer the option of assembling this kit either for dry-hull or wet-hull operation. Now, that's smart tool-design! And greatly increasing the market this project is aimed at.

    A dry-hull would demand gluing the two long center hull pieces together, then bonding the bow to the main hull, and making up a set of bayonet rings to the stern of the main hull and forward end of the tail section. Access would be the radial break between bayonet rings.

    If configured for a wet-hull -- as I'm doing with the kit Andreas provided me -- you would bond the forward and after hull pieces only to the bottom main hull piece, leaving the long upper hull half as the removable element, providing plenty of internal access in which to mount and set-up a removable WTC (Caswell-Merriman SubDriver in this example).
    Who is John Galt?

    Comment

    • He Who Shall Not Be Named
      Moderator
      • Aug 2008
      • 12241

      #3


      An artifact of Andreas' lay-up process are the radial and longitudinal flanges at the edges of the GRP parts. The flanges are beneficial in that they contribute a great deal of rigidity to the parts, and offer considerable glue area when bonding adjacent sections of hull together.

      However, in those cases where you want a much stronger bond between the hull parts, it's best to grind away the flange and to lay in reinforcing strips of glass tape on the inboard side and saturate the tape with epoxy resin. Part-2 of this article will deal with that and other kit assembly issues.



      The two pieces that make up the stern section of the hull. Here you can see, to better advantage, the radial and longitudinal flanges at the edges of the two pieces.
      The lower pieces is a hatch incorporated in the dry-hull version of the hull -- needed to access the linkages and running gear in the wet stern section. Not needed on the wet-hull version I'm assembling, I bonded the hatch permanently to the after portion of hull.
      Who is John Galt?

      Comment

      • greenman407
        Admiral
        • Feb 2009
        • 7530

        #4
        Beautiful detailed work. looks Good! By my reckoning its going to be about 43" long. Thats the same length as the 1/72 Revell Skipjack from tip of prop cone to bow. May I ask what Subdriver you are going to use? Ive always wanted a 571
        IT TAKES GREAT INTELLIGENCE TO FAKE SUCH STUPIDITY!

        Comment

        • He Who Shall Not Be Named
          Moderator
          • Aug 2008
          • 12241

          #5
          Originally posted by greenman407
          Beautiful detailed work. looks Good! By my reckoning its going to be about 43" long. Thats the same length as the 1/72 Revell Skipjack from tip of prop cone to bow. May I ask what Subdriver you are going to use? Ive always wanted a 571

          Likely a 3", two-motor affair

          Click image for larger version

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          Who is John Galt?

          Comment

          • Albion
            Captain
            • Dec 2008
            • 651

            #6
            Maybe offer the brass props in the "gold" kit ;)

            Next time someone points out it takes 42 muscles to frown, point out it will only take 4 muscles to b1tch slap them if they tell you how mnay muscles you need to smile:pop

            Comment

            • greenman407
              Admiral
              • Feb 2009
              • 7530

              #7
              OK so I cant help myself and HIJACK Daves thread and post some Nautilus pictures.
              IT TAKES GREAT INTELLIGENCE TO FAKE SUCH STUPIDITY!

              Comment

              • greenman407
                Admiral
                • Feb 2009
                • 7530

                #8
                couple more........
                IT TAKES GREAT INTELLIGENCE TO FAKE SUCH STUPIDITY!

                Comment

                • He Who Shall Not Be Named
                  Moderator
                  • Aug 2008
                  • 12241

                  #9
                  NAUTILUS PART-2
                  Part - 2 to this article has got to be the most boring installment to this WIP! No flashy painting techniques. No exotic model building techniques on display. No combination of kit parts to make this thing look like the eventual USS NAUTILUS.

                  BORING!

                  But, what I'm presenting here is a vital phase to the kit assembly task: the gluing together of the separate hull sections; the bonding of the bow to the lower hull main section, and bonding the stern section (itself made up of two separate parts) to the lower hull main section. The desired result will be a removable main hull upper piece that permits access to the models interior. The huge equatorial spit in the hull making WTC installation and removal an easy and quick task.

                  About this specific kit: Most manufacturers produce GRP hull pieces that arrive warped out of shape, pieces that demand of you the design and creation of specialized holding fixtures, weird hand contortions, and other means of coaxing the parts into proper alignment as you bond them together.

                  Not the case with this model! Andreas has produced GRP parts of very, very tight maintenance of original tolerance. Near zero warpage. This model kits GRP hull parts rigidity owed to his incorporation of longitudinal and radial flanges. Those flanges both a blessing and a curse: the flanges kept the GRP parts true of form, yet most of those flanges have to be ground away to permit application of internal layers of reinforcing glass tape and resin as the parts are bonded together.




                  The end game her e will be the permanent bonding of the bow and stern sections to the lower hull, leaving the upper hull to be removable in order to access the interior of this wet-hull type r/c submarine.




                  To insure correct alignment of the hull sections to one another I first secured them into a coherent hull assembly with the aid of brass straps, those straps bolted to adjoining hull sections -- three straps per adjoining parts sufficient to insure a secure, non-slipping union. By making the holes in the straps a sloppy fit to the machine screws, enough slop is present to permit adjustment to me made as the parts are brought into symmetric alignment with one another.





                  First task was to drill and tap holes needed to pass the 2-56 machine screws used to hold the straps tight that pulled together adjacent GRP model parts. Initially I used masking tape and hand pressure to hold a pair of parts together, but only long enough to work out strap placement and where to drill the holes.





                  Use of a three-foot straight-edge -- placing it to the sides, top, and bottom of the central 'main body' portion of the hull -- was used to check symmetrical alignment between the bow and stern sections to the main body. Loosening the involved straps, repositioning the fit between the sections, and re-tightening the straps was all that is involved to move things around till they are in proper alignment.

                  To ensure all elements of the hull lined up correctly I included the (eventually) removable upper hull section to the assembly. Once a proper fit between the parts was achieved the upper hull half piece was unstrapped, and the process of bonding the bow and stern pieces to the lower hull begun.







                  For the moment, the radial and longitudinal flanges are left on all the parts, and the hull sections are strapped together. Once the hull is assembled, the individual straps are identified with a number, that corresponds to the same number printed on the hull. The assembled hull was then taken apart so I could go about the nasty work of grinding off the radial and longitudinal flanges, with the exception of the flanges between main hull halves and the bow and stern part radial flanges that would mate with the upper hull section.




                  The longitudinal and radial flanges at the edges of all GRP hull parts -- to be joined permanently with epoxy saturated fiberglass strips -- were ground away with moto tools equipped with sanding drum and carbide cut-off wheel. The objective is to present a uniform flat internal surface upon which the reinforcing strips of fiberglass cloth can lay and soak up resin, without the internal 'bump' of a flange getting in the way.

                  The after hull piece has a 'hatch' which has utility on a radially broken hull, but is useless when you are making a wet-hull with the big upper hull half made removable for access. So, you see the flanges between this after hatch and rest of the stern piece being ground away in preparation of bonding.




                  In some cases, like this, it's a good idea to remove the straps before getting into the glass bonding chore. The strap screws projected into the hull a bit and would interfere with the lay-up of the fiberglass tape used to lap over the seams between hull parts.

                  So, to keep things together, I tack glue the hull parts together with CA adhesive, then remove the straps and screws. The machine screws cleared away it was a very simple matter to mix up some laminating epoxy and lay in the fiberglass reinforcing strips within the hull assembly.




                  Four-ounce weight (fiberglass cloth/matt density is expressed by weight per square yard) cloth tape was cut into inch-and-a-half wide strips. Those strips cut to a length that would girdle, from the inside, one-half the diameter of the hull. These strips, when saturated with resin becoming the reinforcement that would permanently bond adjoining hull sections together.

                  A neat way of working out developed length of the strips is to use a malleable item, like solder wire, as demonstrated here, to determine the required length of strip needed within the model, then to straighten it out and use that to determine the length of the strips required. Fiberglass matt and cloth is best cut out with a disc-blade knife as seen here. A cutting board of wood works very well, as long as the direction of cut is in line with the grain of the woods surface.




                  The reinforcing fiberglass tape is laid within the model after first brushing on some catalyzed laminating resin. Note the long handle to the disposable brush here -- it permits easy application of resin to those areas not easily reached by hand.

                  The many holes used to secure the metal straps were first covered from the outside with pieces of tape. Once resin was laid up within the hull it filled these holes -- the hardened resin restoring the outside of the part ... no more pesky holes to fill and be bothered with later.
                  Who is John Galt?

                  Comment

                  • greenman407
                    Admiral
                    • Feb 2009
                    • 7530

                    #10
                    Dave, whats the advantage to the bow and stern being bonded to the lower section? Usually we make a Z-cut.
                    IT TAKES GREAT INTELLIGENCE TO FAKE SUCH STUPIDITY!

                    Comment

                    • He Who Shall Not Be Named
                      Moderator
                      • Aug 2008
                      • 12241

                      #11
                      Originally posted by greenman407
                      Dave, whats the advantage to the bow and stern being bonded to the lower section? Usually we make a Z-cut.

                      A fair question, and one deserving a good answer.

                      .... and I'm so glad that one of you tobacco chewing, gum smacking, southern degenerates have taken a few minutes away from your loud, oily, stinky, loud, uncouth, and loud speed boats to, ever so briefly, rejoin the race of Man!

                      I would have gone for the Z-cut had it not been the necessity to keep all the bow plane retract mechanisms in the same portion of hull in which the SD will be mounted -- doing it the way I'm describing in the WIP keeps the linkage a simple affair up forward.

                      ... Now: back to your moon pies and RC cola you alligator dodging Red-Neck, you!

                      M
                      Who is John Galt?

                      Comment

                      • greenman407
                        Admiral
                        • Feb 2009
                        • 7530

                        #12
                        Well Thank You Sir for that Info. NOW YOUVE OPENED UP A CAN OF WORMS! RETRACT Mechanism!!! Thats so cool! Just like in the Gato? Or a bit different? Please ......carry on. By the way.....I dont chew Tobacky.....but I am a degenerate........SO THERE!!! I guess I told him huh.
                        IT TAKES GREAT INTELLIGENCE TO FAKE SUCH STUPIDITY!

                        Comment

                        • He Who Shall Not Be Named
                          Moderator
                          • Aug 2008
                          • 12241

                          #13
                          Originally posted by greenman407
                          Well Thank You Sir for that Info. NOW YOUVE OPENED UP A CAN OF WORMS! RETRACT Mechanism!!! Thats so cool! Just like in the Gato? Or a bit different? Please ......carry on. By the way.....I dont chew Tobacky.....but I am a degenerate........SO THERE!!! I guess I told him huh.

                          LOL. Arn't we all?...

                          Yeah, same type retract -- two opposed spur gears, meshing to counter-rotate. Simplicity itself. Only difference between the NAUTILUS unit and the one for the GATO is the greater radius between strut and spur gear pin.

                          M
                          Who is John Galt?

                          Comment

                          • He Who Shall Not Be Named
                            Moderator
                            • Aug 2008
                            • 12241

                            #14
                            USS NAUTILUS, PART-3

                            Unlike most other wet-hull type r/c submarines, this one -- because of the need to achieve an unbroken linkage to the SubDriver (WTC), located in the lower hull, and the bow plan operating and retract linkages, also located in the lower hull -- features a U-cut type break between the two hull halves. With the U-cut both radial breaks occur from centerline up to the top of the hull.
                            Unfortunately, the U-cut prevents tilting of the upper hull as it's placed down on the lower hull. Where the more familiar Z-cut, with its high radial cut aft and low radial cut forward permits use of a radial capture flange forward, and a single machine screw aft to secure the entire hull assembly -- an assembly that requires angling in the two hull halves during assembly. Not so with a model. making use of right-angle U-cuts.

                            Presented here is how I worked out the fasteners used to hold the two hull halves together, as well as how 'indexing bolts' (as the German's would describe them) are employed to index the two hull halves tightly together against transverse loads.



                            With this type hull separation scheme some means of registering the two hull halves together has to be devised so that they fit together as a tight, non-shifting unit, secured with the minimum number of mechanical fasteners.

                            I worked out an array of indexting pin-in-hole bolts along the longitudinal flanges of the upper and lower hull pieces to prevent transverse motion of the assembly. I would love to claim authorship to this feature, but ....

                            ... It's a system I stole from Andreas (who produces this kit). He chronicled the use of the pin-in-hole indexing array in this excellent U-1 WIP thread, http://www.modelboatmayhem.co.uk/for...6a4d50934dcc7b

                            Longitudinal regidity and alaignment was assured by the vertical flanges at the radial edges of the upper and lower hull.

                            Closure was achieved by a fore and aft machine screw holding the upper hull down upon the lower hull -- that required manufacture and installment of two brass foundation pieces to receive those screws.



                            The pin-and-hole indexing array, that would register the longitudinal edges of the upper and lower hull halves together, started by working out an even spacing between the pins and holes along the length of the flanges. This done with Sharpie-pen and ruler.



                            The pin-and-hole indexing array started with laying out of longitudinal lines. That job best done with a compass: the pen point set high enough to cause the shank of the compass needle to ride along the outer face of the hull as the tool is drawn along, its pen tip inking a line along the length of the flange face.

                            I elected to install the pins within the flanges of the upper hull half, and the holes to receive the points of those pins drilled into the lower hulls longitudinal flanges.



                            The compass was adjusted to put the inked line in the center of the flange. As the tool retained its initial setting during the mark-off of the four longitudinal flanges, I was assured uniformity of line-to -hull-surface spacing. close enough for government work. However, as a check, I would later use an old pattern-makers trick to assure a more precise mark-off to assure proper alignment of pin-to-hole.

                            The trick is to work one pin-hole pair at a time. Not till a set of pin and hole had been successful achieved, would I move on to the next set.

                            The process: First, I drill a 1/16" hole into one of the marked spots along the longitudinal flange of the upper hull. A short length of 1/16" diameter brass rod is chucked up into a moto-tool and spun as I filed one end to a blunt point. The pin was then inserted into the hole, pointy end of the pin projecting over the flange face by 3/32".

                            The next step is to accurately mark onto the lower hull longitudinal flange where the center of this pin goes.



                            I applied a very, very small amount of oil paint (black) to the tip of the friction fit pin, then carefully placed the upper hull down onto the lower hull. I kept pushing till the pin makes contact with the lower hulls longitudinal flange -- and kept pushing till the pin was pushed back with its tip flush with the upper hulls flange face. Removing the upper hull revealed a small dot of paint on the lower hulls longitudinal flange where I would drill a hole to pass the pin. That hole slightly larger than 1/16" (.062") -- this to provide a non-interference fit between pin and hole. That bit was a .064" drill. This produces a very tight, non-interference fit between pin and hole.

                            After removing the upper hull, the pin is pushed to project it's tip 3/32" past the plane of the flange, and CA applied to the inboard side of the flange to affix the pin in place. The two hull halves were assembled to insure a correct fit, then separated and I moved on to the next pin-hole combination. the cycle repeated till the job done.



                            The completed pin-in-hole array seen along the longitudinal flanges of the upper and lower hull halves.

                            The forward screw foundation. Manufactured from 1/2" wide, 3/32" thick brass strip, and bend to a 'Z' shape, is seen here temporarily held within the forward section of lower hull with two 2-56 X 1/4" long machine screws -- these screws eventually removed to clear the way for installation of the eventual forward acid-etched deck piece.



                            Two hull closure machine screws, one forward the other aft, eventually secure the upper hull to the lower hull. The two foundations (the forward one seen here) becoming the interface fixtures between the two halves.

                            (Note the second hole, aft of the other, in the trough of the upper hull. The initial intent was to employ a longer foundation tongue, but that was found to put too much strain on the right-angle bend at the bottom of the foundation piece. With the shorter moment the assembly became a bit more ridged).



                            Temporarily attached to the forward portion of lower hull, the forward screw foundation is seen with the upper hull not yet positioned in place. You can see how a securing machine screw would pass through the hole in the trough of the upper hull, pulling it down and onto the foundation, holding the hull halves in place.



                            This is the end-game: A solid, ridged foundation upon which the inboard side of the upper hull rests upon. So arranged the upper surfaces of the hull halves match perfectly.

                            So, with the pin-in-hole array I've forced the longitudinal union between the two hull halves to index tightly against transverse loads; and the two foundations with securing screws pulling the upper hull half down upon the lower hull half.



                            The upper hull was removed, the lower hull inverted, and CA applied to the foundation-hull matting surfaces, and when cured hard, the temporary securing screws were removed. Then some laminating resin was catalyzed and reinforcing strips of two-ounce glass cloth laid in to strengthen the foundation bonds.
                            Who is John Galt?

                            Comment

                            • He Who Shall Not Be Named
                              Moderator
                              • Aug 2008
                              • 12241

                              #15


                              NAUTILUS PART-4

                              In this part I'm concentrating on how to handle, cut, and trial position the two acid-etched deck pieces. As I departed from the radial aft break to the hull -- this kit designed as a dry-hull with a single radial break aft employing a watertight bayonet type closure. However, I opted for a wet-hull arrangement which, as the hull kit parts were arranged required two radial backs atop the hull. This change meaning I had to split the forward acid-etched deck piece into two pieces in order to work over the forward radial break.

                              In addition to outlining the care and feeding of this kits acid-etched deck pieces, I'll also give you some insight into just what the acid-etching process -- more correctly described as, chemical machining -- entails to give you a better idea of the end-products strengths and weaknesses.




                              THIS is one complete kit: detailed illustrated orthographic and isometric drawings; two beautiful cast brass propellers; GRP sheet marked off to indicate where to cut; bubble free perfectly symmetrical and tight fitting resin pieces; and a complete set of acid-etched parts for the deck, sail bridge, radar reflector, and even a painting stencil used to spray-brush on the large white '571' that goes on each side of the sail.




                              First step is to part the two deck pieces from the tabs that connect them to the fret. This best done with a sharp knife pressing down onto a firm, un-giving surfaces -- such as a sheet of glass or, in this case, a slab of sheet iron. Place the blade edge perpendicular to the work, where the tab meets the part, and press down firmly. 'Snap'! As the part is cut free of the frets tab.




                              To insure I made the initial forward brass deck cut exactly over the radial seam at the bow, I laid in the two acid-etched deck pieces -- which indexed perfectly within the shallow trenches of the hull there to fit them flush with the top of the hull -- and only then laid down a straight-edge and made the first light passes with a brand new #11 blade. The forward acid-etched deck piece was removed from the hull, placed on the cutting plate and at least ten light passes of the knife made, using the initial cuts to guide the blade. The piece was flipped and a straight-edge used to guide the blade as that side was scored.



                              The acid-etched deck pieces are chemically cut from brass sheet. This is flimsy stuff as it is, but after eating away a substantial portion of the material to achieve the high relief and through detailing, the part become exceptionally prone to handling damage.

                              For this reason, other than using a very thin diamond saw, you should refrain from using traditional sawing tools to part one acid-etched part from another. Instead, as I've illustrated here, you make knife cuts along both faces of the piece; sandwich each half between hard-wood strongbacks; and slightly flex, back-and-forth, the parts at the knife cut till the metal fractures.



                              In this shot, you can make out the slight recess in the bow that permits the face of the deck piece to mount on the same plane as the GRP hulls deck. Incidentally, the seam between acid-etched deck and hull, not by any accident, is the same demarcation line between the real NAUTILUS hull and deck. This is one accurately engineered and detailed model kit!

                              Seen to good advantage here is the break in the forward acid-etched deck piece made to accommodate the forward radial break between upper and lower hull halves.




                              Andreas lavished a great deal of research effort and drawing preparation on his kit. It shows in the highly detailed brass metal deck kit parts. He employed a second-party contractor to produced the acid-etched parts -- that outfit using Andreas' art-work to render the engraved and opened details. The process in professional circles referred to as, two-face 'chemical machining'. Acid-etching to you and me.

                              The process goes something like this: A piece of brass or stainless steel plate is cleaned and both sides coated with an air-dry photo-sensitive resin. the sensitized metal sheet is sandwiched between two indexed negative/positive film masks. The top mask represented those portions of deck that will be cut all the way through as well as those areas that are to be cut half-way through. The bottom mask represents those portions of the deck that have to be cut all the way through.

                              Once the photo-sensitive resin is exposed (typically an intense ultra-violet light), the masks are removed, and the sheet agitated within a developer solution that removes/protects the light activated portions of resin. At this point specific portions of the sheet are protected by the resin, the other portions of metal unprotected and now subject to oxidation. The developed sheet is then subjected to either a hot acid or caustic solution soak/impinging spray. Oxidation or corrosion eats away those areas of sheet no longer protected by the resin coating.

                              Hence the term, 'chemical machining'. And you wind up with the thin metal sheet (the 'fret' in some circles) possessing incredibly defined engraved and open areas. Typically, for economies sake, the fret will contain many different acid-etched model parts and masks -- the items within the fret held in place my tiny tabs, elements of the original art-work.







                              This little scratch-build model demonstrates the correct selection of materials and fabrication process to suit specific tasks: acid-etched brass sheet to form cockpit detail, markings painting masks, l.g. doors; cast resin parts for small parts of compound curves; and vacuformed polystyrene sheet for large, hollow, low-weight structures of compound curves.




                              Why do I know so frig'n much about the process of acid-etching? Because I do it myself, in-house.

                              Like all model building techniques this process has its uses. But, only in specific situations. The talent is knowing what fabrication process to employ for specific parts, and when. Acid-etching employed here to achieve incredibly small, well detailed parts and and painting masks.

                              Andreas' kits is an example of correct material and process selection -- each type material and process suited to a specific type part: laid up GRP where you need thin-walled items of high strength and of compound curve; cast metal where thin walled strength and natural color is required; and acid etched items where thin-section plate of fine surface detail is desired. The right material and fabrication process for the right job.




                              The one mystery as to the NAUTILUS detailing not resolved in the kit is the number, placement, and size of the bottom hull ballast tank flood and drain holes, and main seawater suction and discharge holes.
                              Searching my files I found this excellent Jim Christley drawing showing the as-launched NAUTILUS in profile, both cut-away and external. And it's the upper drawing that revealed a great deal of information on those hull penetrations -- holes I'll have to cut into the lower hull for both scale and functional reasons.

                              Who is John Galt?

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