Update 3/20/16: Duplicating the Black Dragon
Posted by Matty on March 20, 2016, 16:03:55
With apologies for such a long absence - at least, lacking reports of any actual progress - I'm going to give you some rare (for the last 10 years, anyway, since I stopped giving away these) glimpses of Matt Stein Models' technique, progress, on a current product in development. Which, as I (yet again am forced to) pack everything up and move, is one of only two remaining items - and the sole Matty's Models project - on the bench: |
Click on Image for FULL RESMy 1/535 "Black Dragon", stripped of nearly all fiddly bits - catapults/floatplanes, masts, antennae/gun directors, and even several quad-40s (which were going to go, anyway - see below) - is having her lower hull molded in RTV rubber, to develop a correction for the "Flat Bottom Boat" hull of this ubiquitous, affordable and immortally-classic Revell Missouri kit, from which she was accurized.
Although low on the Matt Stein Models commercial agenda for new releases, that agenda is shot to hell these days, anyway, by an unexpected move - and this project, the last scheduled for packing away to storage, ironically became the latest beneficiary of attention, and progress, in the meantime.
While the above pics may look like the model has simply been lowered into a large mass of RTV, no decent mold of this hull-bottom could ever be obtained that way. The problem, first of all, is the trapping of air pockets - especially large ones, between the twin skegs/rudders/prop struts (see below), but also smaller bubbles to be expected anywhere, particularly along the bilge keels. Nor would vacuum de-airing be the solution - even assuming you did have a "pressure pot" large enough to enclose this entire configuration - as the vacuum would risk cracking/rupturing (if not outright exploding) any assemblies which trap significant air: for example the 5-inch turrets. And finally - all air-trapping concerns aside - just submerging an entire (hollow) ship model into (dense) RTV presents the simultaneous difficulties of holding it down far enough, yet still upright, and not too deep, leaving sufficient RTV under the keel: the problems multiply exponentially.
Thus, the current state-of-the-art approach at Matty's Models is always to find a way to paint on the critical, innermost mold surface:
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___FULL RES_FULL RES_____In the earliest pics I took of this project (left), the process is already well underway: the model, resting on its deck and penetrating a membrane of packing tape over a box deep enough to house the superstructure (again, minus masts), is sealed in place and RTV mold rubber applied. Clear tape permits monitoring for RTV leakage (left, bottom), and subsequent correction(s) to reduce waste. Around the model, a cofferdam is lined with scrap RTV blocks (so plan your box length accordingly - which I didn't get quite right, this time), to provide "free" extra bulk in the ultimate mold - this barrier ultimately backed and likewise sealed using aluminum HVAC tape, which stands up on its own.
Once mounted/assembled, as shown at left the hull bottom is then painted - with a small, soft brush, everywhere - with RTV at maximum acceptable viscosity: the purpose being of course to get 100% faithful molding of the entire surface. Although this project actually started months ago, to make good use of the excess RTV (almost always) produced in other mold-making activities, it could be done in a single, dedicated step. The next steps, as shown at right, are sequential pours of RTV - each allowed to harden before the next - building up a significant thickness to support the overall shape of the mold, predominantly but not absolutely required free of (small) bubbles. The difference between this and simply pouring the remainder of the mold - requiring a vastly larger, stronger and more complex scaffolding/setup - is that here RTV is "tricked" into "piling up" over the subject, to form the minimum, physically strong mass desired. The "trick", with each subsequent batch of RTV, is to monitor its viscosity in the pot after mixing - and, at just the right moment pouring the rapidly-stiffening mixture over the subject. Executed perfectly (again, not the actual the case here), this can be completed (for a model of this size) in as little as 3x pours (even 2x, for smaller models): ranging from the consistency of something like a heavy hand lotion (right, top), to about the viscosity of Marshmallow Fluff (remember that stuff?). Inclusion of small air bubbles (or recycling isolated RTV scraps, as seen here) present no problem: the inside lining is already completely established and secure, with these pours adding only mechanical support.
Indeed, once hardened, the entire assembly can then be removed from the box:
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___FULL RES__FULL RES___At left, looking like she is sinking by the stern, through a clear sea surface - itself another great discovery, with potential for dioramas - the RTV leakage through the membrane is not as bad as it looks: all having flowed downward and away from the deck, and its entanglements (still, I'm absolutely glad to have removed all the catapults, A/C, crane, etc.).
With the tape removed, as at right, the thick mantle of RTV looks like a massive, entrapping raft of ice - yet another diorama possibility, and also RTV can be sculpted very interestingly - but of course the purpose here is that the mold lining is well-supported. Such that now the entire assembly could be "sailed" in a tub of RTV, its thick skirt of rubber now keeping it level, and mantle guaranteeing sufficient thickness under the keel - meanwhile any air pockets (even substantial bubbles) essentially be damned! Still, further avoidance of air-trapping can and was done: first trimming off the hairy edges of the skirt (right, at bottom), and then tapering these edges to flare back smoothly into the underlying blanket, covering the hull.
The above was done, as seen in the first/lead-in pic, above, as well as the following:
Click on Image for FULL RESNote a LOT - perhaps fully a third or more - of the total (relatively expensive) RTV got trimmed off. But of this, very little will ultimately be wasted. Instead most if not all, chopped into rectangular blocks and/or small "cobbles", will be recycled directly back into this (and other) completed mold(s). Indeed, some 25% or so of the RTV seen here has already been recycled - exactly as described above - from previous molds! So, you can see the above type of variation on the standard, "pour-everything-once" method also can yield significant improvements in economy/efficiecy.
In any case, that's where this project sits as of today - soon, actually, to be two projects: the hull-bottom upgrade for the Revell 1/535 Iowa-class kit and the refit of my Black Dragon - USS New Jersey at Leyte Gulf - whose deck needed repainting anyway, ergo removal of many small parts - which, in turn, were slated for replacement with Matty's Models' Twin-5inchers, Quad-40mms, Mk37 Directors, (upcoming) OS2U KingFishers, GMM and WEM PE - and/or straight reworking/improvement(s), anyway.
So, once the above mold is completed and lets loose of my Black Dragon, I should be able to work on/show you that refit, as well...