Improving the SubTech 1/60 ALBACORE phase-2 Kit, Part-4

A Report to the Cabal:

Just about finished with the two sail masters. And I'm well underway in making the
hybrid tools for the phase-3 tail-cone, that item needed to produce a part I can
turn into a phase-2 tail-cone production master.

The tail-cone tools I'll be making are hybrids, that is to say, they consist of a hard-
shell and a soft rubber insert. I'm using a 'brushable' type RTV rubber, produced
by BJB, http://www.bjbenterprises.com/silicones.html .

The advantage of this type tool is that the shell is so conformal to the shape of the
master that only a small amount of the expensive rubber is used. Traditionally this
'mother-mold' and 'glove-mold' type tool was built by first building up a clay
mask over the master, the clay a stand-in for the rubber, then building a mother-
mold over the clay using either a GRP lay-up or building the case from ceramic,
then scooping away the clay, then pouring in liquid rubber in the void between
master and inner wall of the mother-mold/case given form by the departed clay.

What I'll be showing off in the next couple of chapters is how to make such a

hybrid tool -- specifically, how I make the various type of tools needed to represent the phase-1, 2, and 3 type stern-cones. Additionally, I'll likely use the same tool making process to produce the two different type of sails for the ALBACORE upgrade kit as well.

Read on:

The phase-1 and phase-2 sail masters ready for another coating of primer. At this point I have caught up the phase-1 sail with the other, having just removed the trailing edge and building up that area of the phase-1 sail to represent the initial 'small cord' dorsal rudder. Though the two sails share the same cross-section, they do vary in the shape of the top as well as how and where the dorsal rudder breaks and is suspended off the trailing edge of the sail -- there simply was no practical way to build a single sail master that would represent all variations it underwent during the ALBACOR's fruitful career.

The phase-2 sail featured a 'bump' atop the sail. I'm not clear why this was done (the ALBACORE was never intended for under-ice work), but something in my deep, dark memory suggests that a new scope was added that necessitated raising the sails height, hence the 'hump' ... Steve Reichmuth: help! Why the hump up there?

Anyway, working from a phase-6 piping TAB (Training Aid Book, used by the crew to familiarize themselves with the boat's systems) drawing I saw this hump defined by an outline. I lofted that dope off the drawing to atop the sail top master by converting the TAB drawing scale to the scale of the model with a set of proportional dividers.

How many of you out there know how to draft and read a set of simple orthographic drawings ... and I don't mean that automated CAD crap! ... I mean, can you do technical illustration with pencil, pen, straightedge, curves, and compass?

No? Then you're a dumb-ass! Learn!

I built up a thin plastic spine that was glued atop the master, you see here I've already built up filler and sanded it back to contour on one side of the spine. I assume that this hump originated with the phase-2 program ... anyone out there in Cabal land know different?

As shaping went along I drew in some transverse pencil lines. Sighting along these revealed asymmetry problems which were dealt with by either more filler or further work with file and sanding sticks. The Reference photo here is of the ALBACORE as it is today, so we're looking at the phase-6 sail in the photo.

From the phase-1, 2 (and maybe phase-3) propeller master I created a high-temperature rubber tool, from which I cast the required number of white metal propeller parts, needed to fill a current SubTech order. These are much better looking, and a bit stronger, than the initial kit provided propeller. The propeller comes faced off, bored to accept a 3/16" propeller shaft, and equipped with a 6-32 set-screw needed to secure the propeller to the propeller shaft.

I was compelled to make the new propeller master, tool, and parts because the new stern-cones are now of correct diameter at the stern.

Facing off a cast white metal propeller part on the little Taig machine lathe. Grunt work!

While I was in a propeller fabrication mode, I also knocked out twenty propellers I promised Steve Neill -- he needs these to fill orders on his nice little vacuformed 1/144 GEORGE WASHINGTON kit. It's the same type propeller initially used on the SKIPJACK class boats (and I've just learned from John Anderson, also on the initial batch of ETHAN ALLEN boats). Damn things are tiny!

A hybrid tool will be built from which to produce phase-3 and on tail-cones i.e., tail-cones without horizontal stabilizers; simply cones with four punch-marked indicators showing where to drill the holes that will accept the operating shafts of the X-tail full-flying control surfaces.

Here a 'parting board' has been set up to mask off one-half of the tail-cone master. The base of the tail-cone master will be RTV'ed to the white portion of the fixture, then clay will be built up forming a damn to contain the glove-mold rubber and fill the gaps between master and parting board.

Before I can make up the phase-2 tail-cone (the only phase where the cruciform, ahead of the screw, control surfaces was investigated) I make the phase-3 and on tail-cone master, from that master I pull an epoxy phase-2 tail-cone production master, outfit it with a set of horizontal stabilizers, the use that production master to make a phase-2 tail-cone production tool and, finally, cast polyurethane kit parts.

Anyone out there following this crazy horse-shit?!....

The master mounted within its holding fixture with clay damn in place, to contain overflow of the 'brushable' mold making RTV rubber I'm using to make the glove-mold. Once the rubber cures I cut away the excess, wax the two faces of the holding fixture down (including the top of the rubber element) then build up a mother-mold from GRP (formed from West System epoxy resin saturating seven-ounce glass cloth).

BJB's TC-5040 'brushable' RTV silicon rubber is a low sag, rather thick formulation of mold making rubber. However, to increase its thickness even more there's an additive that can be mixed in after catalyzing the rubber. The initial coat of rubber went on thin. A second layer, applied after the first had cured hard, was thickened and gopped on, it being an easy matter to pack the stuff high without fear of it running off -- made thick enough, the TC-5040 will stay where you put it. Of course, care had to be taken to de-air the mix in the vacuum pot before pouring and pulling the rubber into shape over the master -- failing to do so will entrap bubbles in the mix, bubbles that would later crush or expand, distorting the mold when subjected to a differential air-pressure during the part casting process (pressure or vacuum assisted casting, for example).

The first coat of TC-5040 applied not only to the tail-cone job, but also to a new sail tool for my 1/96 SKIPJACK kit (Kevin Rimrodt and I are ramping up for a reintroduction of this kit, at a lower retail price ... that means more customer involvement with the kit assembly). There was leftover rubber so I quickly brought out a set of gear reduction body production masters and made another tool for that item. Waste not, want not! Rubber is expensive!

Oh, the term, 'brushable' is a misnomer: You don't use a brush to pull and push the TC-5040 around, you use a mixing stick, credit card, putty-knife, or other such tool.

Tomorrow I build up the other half of the hybrid tools.

Stay tuned, sports fans!