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the SubDriver becomes modular

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  • #46
    Always a pleasure to annoy you David, i'm fine, goofing around on this ball of dirt, and running around in the cave.
    Nice solution the modular style, so, WIP V80??, it should be cured by this time.

    Fertig zum unterwasser.


    • #47

      Before the mid-day break for my hideous nap I got this much done converting a 2.5"-to-2.5" pre-production union casting into a 2.5"-to-3" union. I turned a new RenShape radial flange for the step-up required, using the core of a ballast tank half of a 2.5" union for the innards of this pre-production master.

      Anyway, here's how far I got this morning:

      Later I'll produce a step-up union for a larger, 3.75" cylinder.

      "... well, that takes care of Jorgenson's theory!"


      • #48

        It’s one thing to come up with a clever innovation on an old concept – maturing the WTC to a proper modular system being discussed here as example – but it’s another thing to knuckle-down and get on with the donkey-work of actually making the items that will comprise the new system.

        You’re looking at about two-hundred-dollars worth of 2” thick, 40 lbs. per-cubic-foot, pattern making medium. Most of it soon to be reduced to chips on the shop floor. God’s answer to pattern makers, this extremely dense polyurethane foam is so much superior to the Kiln-dried, carefully selected pattern maker woods used almost exclusively a half-century ago. Sugar Pine was my favorite, but all that timber has long been pulled from the bins, completely replaced by the synthetics. Thank you chemical-scientists!

        No grain. No pitch. No drying and cracking over time. RenShape takes to all adhesives, and its high pH sets off CA glue in record time. If RenShape could only cook!

        Here’s the one I prefer for most of my detail work (the less dense stuff requires extensive filling to get a good surface finish, so I use that version only as floatation material or a back-up to a GRP skin).

        ‘Measure twice and cut once’, as the old Carpenter’s saying goes. And that double-check philosophy starts with a carefully prepared set of orthographic shop drawings, to the scale of the work, and oversized to account for tool and casting shrinkage (that fudge-factor more art than math, I can assure you!).

        I had already made a master, a tool, and some castings of the 2.5” ballast tank half of the 2.5-to-2.5 union. Now has come the time to make like units for the 3” and 3.75” ballast tank union halves. To save myself effort I simply took the core of the 2.5” castings and married them with 3” and a 3.75” radial flange. To ready these cores I milled away the 2.5” radial flanges on the mill as seen here.

        Flat bottom work is easily secured to the milling machines cross-feed bed with a simple L-section aluminum strong-back held down with two jacking screws – holding fixture 101. To enhance the friction between work and bed I glued a big piece of sandpaper atop the bed.

        I’m grinding away the radial flange of the original 2.5” diameter after union half. That work has already been done, as seen with the milled union half to the left. The objective is to insert these cores into larger diameter, RenShape radial flanges. One is for the 3” diameter ballast tank. The other is for the 3.75” diameter ballast tank.

        Here I’m turning a larger diameter radial flange on the lathe. I’m holding a core that will insert within the radial flange, that core containing the foundations and pass-through holes needed to operate the vent valve and (if installed) emergency blow valve.

        This is the end-game for the two ballast mechanism cores: use them as inserts into the larger diameter radial flanges.

        Important safety note: only idiots ware long-sleeve shirt, ties, apron strings tied at the front, and gloves around powerful rotating machine tools! First lesson in shop-class: “Machines don’t care” and, “Machines cut metal and flesh with equal enthusiasm!”

        Yes, sometimes I’m a careless idiot. And sometimes … I pay the price, and got the scars to prove it! Not battle-scars. No! Idiot scars.


        Want some reinforcement? Check out this video (have a puke-bucket handy),

        RenShape is easy to cut but quickly dulls high-speed steel. I found it more expedient to do the rough-cuts on the mill and to finish off the round-work on the lathe. Typically a blank was turned to the outside diameter on the lathe then transferred to the mill and the internal cavity roughed out.

        Notice the Michael Jackson glove-look (I was getting blisters from spending two days driving cross-slides, that is why I’m warring the damned thing).


        Every time I look at the pictures of me operating heavy rotating machinery like this I cringe! (In the caring, and caressing voice of Escape From New York’s villain, A-number-One, as shop-class instructor: “WHAT DID I TEACH YOU!!!!”).

        God-damned! Sometimes I’m such a stupid dumb-ass!! And after seven-decades I still have all my fingers! Amazing.

        "... well, that takes care of Jorgenson's theory!"


        • #49
          Question on renshape. Is a super glued joint strong enough to turn? If yes could you then cut the cylinder with a bandsaw then glue it to a solid renshape plate then finish turning?
          Work is looking good.


          • #50
            Originally posted by Scott T View Post
            Question on renshape. Is a super glued joint strong enough to turn? If yes could you then cut the cylinder with a bandsaw then glue it to a solid renshape plate then finish turning?
            Work is looking good.
            I'm not clear on this. Am I turning a RenShape cylinder or a Lexan cylinder, Scott? I face-mount RenShape to a RenShape face-plate all the time without incident. The CA bond is iron strong with that material.

            "... well, that takes care of Jorgenson's theory!"


            • #51
              So I see you milling out the inside portion of the end-cap/ballast tank and
              wondered if it would be less labor intensive to cut, glue then turn/mill the part.

              A good shop teacher always tells you afterward what is easier.

              Click image for larger version  Name:	cutting.jpg Views:	0 Size:	87.4 KB ID:	134825


              • #52

                Before I once again get bogged down in the minutia of union and bulkhead pattern and tool making, let me remind you of the objective here:

                The creation of a sub-system of various unions and bulkheads that permits the quick, easy, and fastener-free means of assembling different diameters of Lexan cylinder to form a single, purpose built Modularized SubDriver – a MSD suited for a specific shape of r/c submarine hull with a ballast sub-system sized for that particular model. If the positive features of the modularized SD do not strike you immediately, I will later summarize them for you.

                Examine the photo below. It illustrates the basic differences between the old, constant diameter SD with its many fasteners and sloppy external SAS plumbing; and the new modularized SD showing off the fastener free unions between different diameter Lexan cylinders, varied diameters, and no external plumbing.

                And now, back to the shop!

                Most the gross grinding away of RenShape, as I worked the masters, was done on the milling machine. Once I pulled the work out of that nasty Machinist’s version of a wood-chipper I transferred the work to the lathe to finish shaping. Note the use of a simple aluminum L-section strong-back and all-thread jacking screws to hold the work down tight on the mills bed. KISS.

                I’m not at all shy about drilling and taping holes, welding, or bolting things onto the bed, foundation, spindle, or drip-pan of my machine tools if doing so serves my needs; hand and machine tools can and will be modified to adapt them to my specific wants. I run the show here. Not Dremel, Black & Decker, Chicago Machine or Vigor.
                Secure from rant.

                The union and bulkhead masters nearly completed. I still have to insert the forward union ballast mechanisms into the RenShape 3-inch and 3.75-inch radial flanges.

                Some of the abrasives used to improve the finish of the masters on display here. Bondo was used to fillet the ballast mechanisms inserts and radial flanges.

                In background is a 2.5-2.5 MSD, showing that a constant diameter SD is still possible if the right union is employed between the after dry space and ballast tank cylinders.

                The union and bulkhead masters were given a thin coating of West System epoxy laminating resin. I cut the catalyzed resin a bit with lacquer thinner to make it flow on a bit easier with a brush. The work was left to cure hard for twelve-hours.

                At this point the 3 and 3.75-inch diameter forward union halves received their ballast mechanism innards which were CA’ed in place. I poured on catalyzed epoxy to fillet between inserts and the large radial flanges. Another twelve hours for that to cure hard, then all masters were wet-sanded with various #400 grit sanding tools to rough up the surfaces to insure good bonding of the first primer coat.

                The masters were given three coats of primer, sanding between each. They were then mounted on molding boards, containment damns erected, and the first half of the RTV silicon rubber tools poured.

                Here I’m pouring the second half of the rubber tools that will be used to produce cast resin union and bulkhead parts.

                Each union type (ballast equipped and basic) and bulkhead had its own dedicated two-piece rubber tool. The masters used to create these tools are in foreground. Note the 11/32” brass rod cores inserted into those unions that would receive an o-ring which would later make watertight the conduit that would run the length of the ballast tank.

                It’s not enough to provide just a simple sprue hole (the path the resin takes from mixing cup to interior cavity of the tool) when dealing with a tool that takes a significant amount of resin to fill it. A ‘riser’, a reservoir if you will, is incorporated in the sprue to provide make-up resin to back-fill the cavity as entrapped air-bubbles are crushed during pressurization.

                In these tools I provide a riser right under the sprue hole. First, I cut out the riser cavity in one halve of the two-part tool; mark the edges of the riser cavity with black oil-paint, mash the second half of the tool in place to pick up the paint, which indicates the shape of the riser; and cut out the riser cavity into the second half of the tool.

                Each tool is sandwiched between two wooden strongbacks and the assembly compressed together with rubber bands. Sometimes I gang two or more tools together between a set of strongbacks. This is how the tool halves are pressed together as I pour in catalyzed resin into the sprue hole. Note that each tool has marked on its surface the weight, in ounces, of resin it holds. This goes a long way in minimizing the amount of resin wasted after a pour.

                Before the first pour in a tools life I get a close approximation of the weight of resin required through a simple conversion: I weigh the master, multiply by 1.5, and that gives me the weight of resin required to fill the tools cavity. As you can see, RenShape -- the 40 lbs. per cubic foot stuff -- is a bit less dense than resin.

                Detailed to the left in the below photograph shows how I encapsulate the conduit sealing o-ring within the union/bulkhead. The removable brass rod suspends the o-ring within the tools cavity during the pour. After the resin changes state, the tool is pulled apart, and the rod removed, leaving the embedded o-ring and a bore that will pass the ballast tanks 11/32”o.d. brass conduit tube. The conduit maintains watertight integrity between the forward battery space and the after dry space and while doing so passes the power and other leads between the two dry spaces.

                Polyurethane casting resin is mixed up, poured into the tool(s) and the work is placed into a pressure pot which is pressurized to about 15 psig for the time it takes the resin to change state from a liquid to a solid. Typical in-pot time for relatively thick parts like these is about twenty-minutes. The thicker the cross-section of the tools cavity, the more heat generated during the cure, the faster the state change.

                Last edited by He Who Shall Not Be Named; 11-26-2019, 12:33 PM.
                "... well, that takes care of Jorgenson's theory!"


                • #53
                  The pot is de-pressurized, the work taken out, the tools opened and the cast resin parts extracted.

                  Note the brass rod core piece projecting from the cast part. In its center – now encapsulated within the resin part – is the conduit sealing o-ring. When the core is pulled, it leaves the o-ring and a bore that will later accept the conduit that runs the length of the MSD’s ballast tank.
                  "... well, that takes care of Jorgenson's theory!"