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  • Originally posted by Ken_NJ View Post
    I like the way you did this David.

    Difficult to tell in the pictures how you applied the solder.
    What I do for delicate soldering like this is I slice a sliver of solder off of the spool with a Exacto blade. Usually a very tiny chunk, enough for the joint being soldered. Put some paste on the joint, put the tiny chunk of solder on the joint on the paste, then apply heat. The paste holds the solder in place. This minimizes there being a glob of solder on the joint that needs file cleanup if you were to feed solder in from the spool. And only applies the amount of solder that is necessary.
    I've used just the technique you have described, Ken. In resistive soldering: with that process you have to pre-position the solder sliver at the joint, adhering it with the gooey flux, then heating the highly resistive joint with electrical current. Only the joint gets hot, not the surrounding metal.

    Click image for larger version

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    David
    Resident Luddite

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    • How are the pins permanently attached to the model? Also, we need more limber holes.
      Of the 40,000 men who served on German submarines, 30,000 never returned.”

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      • Originally posted by Das Boot View Post
        How are the pins permanently attached to the model? Also, we need more limber holes.
        After the railing assembly is pickled, primed and painted the portions of the pins that insert into the sail are shaved clean, the assembly inserted into the side of the sail and CA applied to the pins from the inside of the sail. The projecting pins on the inside are snipped off even with the inside surface of the sail. Done.
        Resident Luddite

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        • Neat stuff! Thank you for sharing those links.

          Comment


          • Originally posted by Monahan Steam Models View Post
            Neat stuff! Thank you for sharing those links.
            No problem, Nick. Sorry I forgot to post those links initially. Excellent Dive-Tribe Zoom yesterday; you, Ed and Mike are taking us all back to school. Good stuff- tribal knowledge increased a bit after all that. I would love to see these Zooms bumped up to a weekly, not a bi-weekly occurrence.

            David
            Resident Luddite

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            • Originally posted by He Who Shall Not Be Named View Post

              No problem, Nick. Sorry I forgot to post those links initially. Excellent Dive-Tribe Zoom yesterday; you, Ed and Mike are taking us all back to school. Good stuff- tribal knowledge increased a bit after all that. I would love to see these Zooms bumped up to a weekly, not a bi-weekly occurrence.

              David
              David,

              I don't really have a lot to offer at these Drive Tribe meetings (being new) But I do enjoy and learn a lot just listening to those who have the knowledge and skill levels that most of you guys have! I would agree that weekly meetings would be great if possible!

              Rob
              "Firemen can stand the heat"

              Comment


              • Originally posted by He Who Shall Not Be Named View Post

                No problem, Nick. Sorry I forgot to post those links initially. Excellent Dive-Tribe Zoom yesterday; you, Ed and Mike are taking us all back to school. Good stuff- tribal knowledge increased a bit after all that. I would love to see these Zooms bumped up to a weekly, not a bi-weekly occurrence.

                David
                Yes that was a good dive tribe meeting yesterday. Lots of info shared. We went down the tech rabbit hole again. Weekly zoom meetings would be good. Would give more folks a chance to ask questions regarding their builds or share their work.

                Comment


                • With the basic structure of the sail assembled, the brass railing assemblies put away in safe storage, and the FPV camera-transmitter enclosure foundations installed, I test fitted the sail atop the assembled hull and... ******!

                  There was a bow in the sail that resulted in a significant gap between the after end of the sails diesel exhaust muffler fairing and the hull. I'm pointing to it.

                  Unacceptable!



                  The quick, easy fix was to slice through most of the fairing where it met the trailing edge of the sail proper, leaving just a bit of plastic at the bottom. I placed the razor-saw on the after-side of the fairings forward most radial weld line, using that as my guide as I sawed through most of the fairing.

                  With careful pressure I bent the fairing downward to get its ass-end to meet the top of the hull. This over-stressed the little bit of plastic still connecting sail proper from its fairing to maintain the downward slope required so that the after end of the sail-fairing butted down against the upper hull.



                  Of course this resulted in a radial gap were I had sawed away. But this was easily filled with baking soda saturated with CA which formed a hard filler.

                  Note the pink looking 'weld line' running horizontally near the top of the sail. This was formed from Bondo using the same technique I described earlier during restoration of lost weld lines at the longitudinal break between upper and lower hull halves.



                  The inside of the sails fairing also received the baking soda-CA treatment as well.



                  Before filing away excess grout from the surface of the fairing I pencil smeared both sides of the work. As I filed away and got down to the level of the plastic the smear would tell me when to stop with the big guns and switch to descending grits of sandpaper.



                  The objective was to preserve the radial weld line and knock the grout down to conform to the original contour of the fairing.



                  As the sail would contain the removable FPV camera-transmitter enclosure I needed the ability to pop the sail clear of the hull in order to access the system. To achieve that objective I elected to secure the sail to the hull with magnets alone.



                  Eventually the only interface with the sail and the rest of the model would be a flexible hose between the sail mounted snorkel induction valve and WTC's ballast sub-system. In this photo you can just make out the paired magnets within the sail and atop the upper portion of hull where the sail sits.



                  Magnets were also employed to insure a tight hold-down between upper and lower hull halves at the longitudinal break.



                  Basically -- as illustrated by this training-aid I built to show how magnets are employed to hold structures together -- a set of magnets are secured within cast resin foundations which in turn are CA'ed within the model parts. A pair of magnets are so arranged to exert their magnetic force to hold the parts together. The magnets are sized to withstand most operational and handling loads, but not so powerful as to prevent deliberate separation of model parts when required.



                  Years ago, I developed the tooling required to produce cast resin magnet foundations of geometries that would suit just about anything I would want to use the magnets on. In most cases the magnets -- typically of the disc or cylinder type -- are tight interference fits to the foundation that supports them; and those foundations provide the broad footprint that aids in adhering a unit to the inside of a model part.

                  Here I'm using a hand-press to set cylindrical magnets into their respective foundations.



                  Four magnet units are being glued within the base of the sail. As I wanted the bottom end of each magnet to touch the surface of the upper hull, I achieved that objective by pulling a neat trick: As each unit was placed inside the sail, another a raw magnet was placed the outside of the sail to hold the one inside in place. The internal magnet units were lower than they had to be so that when I gently placed the sail upon the upper hull all units would be pushed upward (dragging their outside counterparts upward along with them). This positioned each bottom face of a magnet to just touch the surface of the upper hull.

                  The sail was carefully removed from the upper hull and CA applied to permanently affix the units within the sail. You can make out the raw retaining magnets still clinging to the outside surfaces of the sail.



                  The sail was then firmly held to the upper hull with rubber-bands and the entire assembly inverted to give me access to the inside of the upper hull so I could work out the location of the hull mounted magnets that would interface with the sail mounted magnets.



                  As magnetic force is ruled by the inverse square law, it behooves you to get the joining magnets -- one inside the removable sail, and its counterpart set within the upper hull -- as close as possible when the sub-assemblies are joined if maximum attractive force is to be realized.

                  As the wall thickness of the hull (about .095-inch) represents a stand-off distance between a pair of magnets, just gluing a magnet within the hull would result in a terribly weak attractive force. So, to get the hull mounted magnets to physically touch their counterparts within the sail, holes had to be drilled into the upper hull to pass the hull mounted magnets.

                  But, first, the exact location of where to punch those holes had to be ascertained. That done by simply plopping some magnets down into the inverted upper hull, letting each find its own counterpart, in the sail, through the magic property of magnetism. Neat!

                  I traced the circles where each magnet sat onto the inside of the upper hull and later bored out over-sized holes through which the eventual upper hull magnets would pass so each would actually touch a counterpart up in the sail.



                  Suitably shaped resin foundations, bored with non-interference fit holes, were slipped over a seated upper hull magnet and foundation-to-hull and foundation to magnet unions made permanent with CA adhesive.



                  Though the upper-to-lower hull union was a mechanical one -- the upper hull capture-lip engaging the hulls forward radial flange, and the after end of the union secured with a machine screw -- in some areas along the long longitudinal split some spots presented unacceptably large gaps. These were addressed with magnets that worked to pull the two hull halves tightly together when assembled.

                  A ferrous item -- a flat file in this case -- with two foundation mounted magnets sticking to it was laid down onto the opposed edges of a hull half (in this case the upper hull). The foundations pulled outboard till they made contact with the inside of the hull and were then affixed with CA. This method insured that the face of each magnet fell across the same separation plane that divided the two hull halves.

                  I found that only four sets of magnets were required to pull the seam down tight when the hull haves were assembled.


                  Resident Luddite

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                  • I love your applications of the magnets David. Very slick.

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                    • I knew a few guys who converted 2 door cars to convertibles. The problem they ran into were weak spots. Frame warp, trunk, doors and hoods that no longer aligned. They ended up having to cut places and wield supports into the body, somewhat like you have had to do. Brings back memories.
                      Of the 40,000 men who served on German submarines, 30,000 never returned.”

                      Comment


                      • Originally posted by RCJetDude View Post
                        I love your applications of the magnets David. Very slick.
                        I learned these tricks from Brian Starkes. He's the one who taught me the utility of these things. Credit, where credit is due.

                        David
                        I only steal from the best
                        Resident Luddite

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                        • David,

                          Magnets are great stuff to use, did the same trick with mine splitting the hull, you're getting there, some detailing and painting still ahead, i wonder how you take pictures with both hands insight, pressing the button with your teeth?, or a hidden third arm from your belly?

                          Manfred.
                          I went underground

                          Comment


                          • Originally posted by MFR1964 View Post
                            David,

                            Magnets are great stuff to use, did the same trick with mine splitting the hull, you're getting there, some detailing and painting still ahead, i wonder how you take pictures with both hands insight, pressing the button with your teeth?, or a hidden third arm from your belly?

                            Manfred.
                            Nothing to it, Manfred. Just like this:

                            https://youtu.be/5i9ojh0SN9w
                            Resident Luddite

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                            • Just want to share what I recently found.
                              Ladies may want to hold onto something.
                               
                              Make it simple, make strong, make it work!

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