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the SubDriver becomes modular

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  • He Who Shall Not Be Named
    replied
    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.

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  • He Who Shall Not Be Named
    replied

    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.

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  • Scott T
    replied
    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

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  • He Who Shall Not Be Named
    replied
    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.

    David

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  • Scott T
    replied
    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.

    Leave a comment:


  • He Who Shall Not Be Named
    replied

    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).

    https://www.freemansupply.com/produc...modeling-board.

    ‘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.

    MACHINES DON’T CARE!

    Want some reinforcement? Check out this video (have a puke-bucket handy), https://youtu.be/lxD7f2zCG40



    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).

    STUPID!

    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.



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  • He Who Shall Not Be Named
    replied


    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.

    David

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  • MFR1964
    replied
    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.

    Manfred.

    Leave a comment:


  • He Who Shall Not Be Named
    replied
    Originally posted by MFR1964 View Post
    So, i locked myself up inside my cave to meditate for some months, and you made this, hats off to you, BUT I STILL HATE YOU !!!!!!

    Manfred.
    Ah! Satisfaction!

    My work is done here.

    What's up Manfred?

    Hate you too, buddy.

    David

    Leave a comment:


  • MFR1964
    replied
    So, i locked myself up inside my cave to meditate for some months, and you made this, hats off to you, BUT I STILL HATE YOU !!!!!!

    Manfred.

    Leave a comment:


  • He Who Shall Not Be Named
    replied

    OK, I’ve finalized how the union piece between two lengths of Lexan cylinder interfaces the devices within. I kept things simple by making it a 2.5” diameter-to-2.5” diameter union. Owing to the unions design feature of being split into two halves, I can exploit the major advantage of the union: its ability to sleeve different diameters and/or lengths of cylinder (module) together to form a single system.

    But, first let’s look, with some detail, on how the union goes together; and how that union mounts the devices that attach to the after and forward faces.

    In background is a Modularized SubDriver (MSD). I have omitted the separate battery WTC for clarity. The after module (the after dry space) contains the propulsion, control, and some of the SAS type ballasts sub-system devices. The forward module (the ballast tank) is a ‘soft tank’ in that it is always subject to ambient water pressure and contains the mechanics that operate the vent valve atop the tank. Also seen in the ballast tank is the emergency ballast blow sub-system -- an option for those who operate in open water.

    In foreground are the two halves of a union with the devices that attach to each.

    Between the assembled MSD and the exploded union halves are (to the left) two union halves ready to be joined with their five securing machine screws. Note the o-ring between the halves. And (to the right) an assembled union ready to be outfitted with devices -- this union ready to join two modules together.



    This shot of our current 2.5” SAS type SD. Note the external plumbing, in the form of two cylinder mounted manifolds and the flexible induction and discharge hoses. So exposed, these external hoses present a likely point of failure. The MSD eliminates the external plumbing, placing all within the two modules, out of harms way.

    Also illustrated here is the major shortcoming of the MSD’s union: an increase of overall MSD length as compared to the short-of-length internal after ballast bulkhead of the standard SD design. However, that extra length is more than compensated for exploiting the unions ability to attach a larger diameter ballast section – for a given ballast tank volume, the overall length of a MSD with an enlarged ballast tank cylinder is significantly shorter than a SD of constant diameter.



    Prototyping affirms that the mechanics dreamed up on paper, on the toilet, or during a fevered skull-session with peers actually works in the physical universe; prototype is the stark reality of what works, and what does not work.

    Case in point: when I showed off the initial configuration of the union, my r/c modeling buddy, Kevin Rimrodt (always delighted to catch me in an error!) pointed out that I failed to provide a means of keeping the union from being pushed aft into the dry space by pressure exerted on the ballast tanks side of the union as the MSD experiences greater depth. He squarely put his finger-of-doom on a potentially catastrophic design error.

    ****!

    I had to equip the after half of the union with a ‘preventer flange’; a ring that would butt up against the forward circular edge of the dry space Lexan cylinder. The alteration of the prototype RTV tool done with relative ease, but only after I modified the after half of the union master to incorporate the preventer flange.



    Only the forward face of the after union master was re-worked. A .095” thick disc of polystyrene was glued to its forward face. The fix was quickly addressed with putty and primer, then used to modify the existing rubber tool to produce the ‘improved’ parts.



    The offending portion of tool cut out, it was reassembled with the modified master installed, and a new batch of rubber mixed, de-aired, and poured through the hole in the strong-back. After the new rubber had cured, the tool was opened up, the master removed, and the tool used to produce the improved union parts.



    The cast resin unions are produced with an outside diameter significantly larger than that of the Lexan tube. I’ve done this to account for the very wide tolerance of diameter between different manufacturers and lots of product on the market.

    I employed a modified face-plate as a specialized lathe holding fixture and a standard four-jaw chuck to hold the work as I refined the diameter of the union radial flanges to suit a specific inside diameter of Lexan tube.



    As the MSD routs the Low Pressure Blower (LPB) plumbing internally, through the union, I’ve eliminated most of the external flexible hose runs that were sometimes problematic with the old versions of our SAS type SD’s.

    Note that the induction and discharge hoses from the LPB terminate at brass nipples set into the union. The discharge line dumps air directly into the ballast tank. The induction line continues on the wet side through a hose that makes up to the top mounted induction manifold. From atop that manifold another length of hose runs up to the top of the models sail where it makes up to the snorkel head-valve.



    I’ve retained my style of ballast sub-system linkage to open and close the ballast tank vent valve. However, there has been an active and very slick offering of alternative vent valve linkage and location at the Nautilus Drydock forum. I regard these as concepts worthy of exploration at a later date.

    The single manifold glued atop the ballast tank routs the induction line that originated at the top of the submarines sail, down into the horizontal induction nipple set within the union, and on into the LPB.

    I included an emergency gas blow bottle, hose, and blow valve in the MSD prototype to insure that this optional installation does not interfere with the other devices within the ballast tank.



    With the MSD battery power enters the after dry space through the motor bulkhead. Here are two examples of the different type motor bulkheads I developed for the 2.5” cylinder: One a single-motor, single-shaft; and the other a two-motor, two-shaft motor bulkhead. There are other type motor bulkheads, but these are illustrative of how I make up the power cables to the devices within the MSD.

    To insure watertight integrity, I use pass-through brass threaded studs through the resin bulkheads to pass the current from battery to MSD devices. The power cables are common 18-gauge two-conductor ‘zip-cord’. I favor Deans connectors between the MSD’s motor bulkhead and battery WTC power cables.

    Note that strain-relief brackets are employed to prevent pulling force being presented to the points where the power cables make up to the studs.



    This is how power is routed from the separate battery WTC to the MSD.

    To make things water-proof (kinda) I coat over the connectors at the studs with RTV sealant. The Deans connector male and female conductors (particularly the positive conductors) are coated with silicon grease before they are made up and the cable ends of the Deans connectors are encapsulated with RTV sealant.

    Yes, with use water gets into the connectors and wicks into the conductor wire. Water is insidious! But, that is easily addressed every couple of years by replacement of the cables. No big deal.





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  • He Who Shall Not Be Named
    replied
    Originally posted by Subculture View Post
    Thread hijack alert!
    Yeah, Andy. I thought I was clear of the Casswell curse, but he just keeps pulling me back in!

    David
    swinging my arms like an ItalianDon

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  • He Who Shall Not Be Named
    replied
    (I'm a Moderator! maybe I have a button here that will turn Mikes CPU into a fragmentation grenade?)

    Leave a comment:


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

    I still know where your 'nerves' are! Enough with all that lathe work, and goopy casting resin I say! Get FUSION 360 and get with it! Do you want me to come over there and show you how to use it?

    (please say no!)
    (where the **** is that 'ban' button!???……………)

    Leave a comment:


  • Subculture
    replied
    Thread hijack alert!

    Leave a comment:

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