From: DMeriman@aol.com To: undisclosed-recipients:;
Subject: R/C"ing the Revell 1/72 GATO Class Static Submarine Kit,
Part-5 Date: Saturday, December 16, 2006 11:35:44 PM Attachments: 000_ygp2E8D.jpg
A Report to the Cabal:
Remember my agonizing, my fear filled proclamations of doom about what would happen when I split the two hull halves horizontally? If, at the time I completed that operation, you had stepped outside and listened carefully, you would have heard a faint, "SPROINGGGG!!!" off in the distance, as the last cut was performed over here in Virginia Beach, Virginia.
Anyway ... and not at all to my surprise ... the stress forces captured by the hull last week as I bent it to shape during hull piece assembly did indeed manifested themselves last night as the flimsier upper hull piece was cut free from the lower hull piece. That problem had to be resolved.
Along with the issue of the lost plastic; the kerf (the material chewed up and spit out by the saw blades as I made the cut between upper and lower hulls) that had to be made back up if I was to achieve a tight fit with little visible seam between upper and lower hull piece. Evercoat Metal Glaze polyester filler to the rescue there.
And there was the matter of permanently attaching the superstructure deck pieces atop the upper hull half ... what was left of the upper hull after my weight reduction hatchet job. Here's a bit of 'synergy' for you: It's the attachment of the deck pieces to the upper hull that straightens up the piece, reducing the degree of warp. Splitting the hull horizontally induced a severe upward bowing of the upper hull piece, addition of the superstructure deck pieces, straitened it back out. A bit of the old Ying and Yang. I love it!
With access to the hulls interior accomplished I did a little work to get the WTC shaft outputs to match, as best I could, with the two propeller shafts -- work I'm currently engaged in.
So, let's get caught up on yesterdays work:
SPROINGGGGG!!! ... Yikes! (kick's the cat for a solid hour)
You're only looking at the stern, the entire upper half of the upper hull describes a very noticeable bow. Obviously, the stress imparted to the hull during assembly of the port and starboard halves, to some degree, relieved itself by assuming the bow when the (flimsy) upper hull was removed from the (stout) lower hull. Got to get this bad-boy back into alignment ... time to get Medieval on its ass!
The hit-man of choice here will be the superstructure pieces themselves; when they are glued atop the upper half of the hull, those pieces will, to a high degree, restore 'straightness' to the hull union. Trust me!
... We will never speak of this again!
Even being terribly careful with the Dremel Moto-Tool circular blade, I still wound up kicking out a substantial amount of plastic as kerf. Add to that the plastic lost as I straightened the cut lines with a sanding block, the total amount of height lost to the two hull halves was about 3/32". I had to make up that material. I did so by first placing a masking tape damn each side of the four matting faces (two on the upper hull, two on the lower hull), filling the space over the mating surfaces to the edge of the masking tape damns with Evercoat filler, waited for it to cure hard, then removed the tape, and block sanded the new matting surfaces to the correct height.
Here you see the thin formula filler, Evercoat Metal Glaze, some cream hardener (MEK paste catalyst), and a multi-sheet mixing palette (God damn! Have I been miss-spelling 'palette' wrong all these years!?! What a dope!), and a common mixing/ application putty-knife.
The buildup of the lost kerf to the matting surfaces of the upper and lower hull halves went very quickly. Here I'm peeling back the low-tack 3M masking tape that had formed the dam that held the Evercoat filler in place till it hardened. Initially I was planning on coating the filler/styrene unions with thin formula CA adhesive to strengthen the bond between them, but found (should have guessed) that the high styrene dissolving ingredients within the polyester based filler would both etch and fuse the filler to the kits styrene plastic. Neat! I observed this same phenomena as I did filler work on the vacuformed styrene SubTech ALBACORE and MARLIN kits, and had forgotten how tenacious the cohesive bond was between filler and raw plastic.
Sometimes things just work out for you ...
... Sometimes not.
Almost finished building up Evercoat filler onto the matting surfaces of the lower hull half. This to replace the kerf lost at the upper hull/lower hull separation plane. The same process will be done to the upper hull once the superstructure pieces have been glued in place, straightening and stabilizing the piece substantially.
After pulling the pieces of tape that constituted the dam that held the filler from the lower hull half, I worked the new faces with a broad sanding block outfitted with #100 sandpaper. You see that big block in foreground. The same operation was performed on the upper hulls matting faces after I had attached the superstructure deck pieces.
There are areas that require cohesive glue applications where the cement has to have 'body' to it; situations where a more volatile cohesive (such as the Ambroid ProWeld I've been using up to this point) would evaporate away as time consuming alignment operations were taking place. Such is the situation, and the demand for a slow working cohesive, with the next job: the bonding of the five superstructure pieces to the upper hull.
I needed this thick, slow-acting solvent cement to hold up during the time it took to coat the four pins that support each of the side superstructure pieces and as I went about the time consuming task of aligning and pushing together the three superstructure deck pieces into one another and onto the top of the upper hull piece.
Common 'model airplane glue' is such a cohesive. But I prefer an industrial version. Specifically, Weld-On #16 Clear, Thickened Cement for Acrylic Sheet, in the Red tube pictured above. You'll find this stuff at plastic supply houses in town -- if they don't have it behind the counter they can order it for you. OK, don't panic! I'm not gluing acrylic sheet. But, believe me, this #16 has the ass to melt and fuse styrene with to trouble at all. It has all the magic ingredients needed to insure blindness and liver cancer, so it must be good, right? I'm sure there's a sprinkling of Polonium in this stuff too.
Note that I installed white styrene plastic sheet lips to two of the three superstructure pieces that will shortly be permanently welded to the top of the hull. Remember, the model is elastic and you want the deck to be as rigid as possible, so providing the butt joints between deck pieces with lap-plates underneath goes a long way to make the structure much more rigid.
Before permanently gluing the three top pieces of superstructure (the deck) together --I already glued the two side pieces of superstructure in place -- I practiced and 'dry-fit' the parts four times before laying everything out, at the ready, for the actual assembly-with-glue process. Get this wrong and you smear glue all over the place and risk having the super-solvent laden cement ruining surface detailing ... and this kit has super-detailing on the deck!
I found that the best method of assembly here was to first attach the bow deck piece, then the center deck piece, then the after deck piece with plenty of glue applied to the lapping plates, but none to the deck-to-deck butt joints -- I didn't want any excess glue to squirt up the seams and mare the finish of the deck detailing.
My initial research into the relationship of the GATO propeller shafts, their angular displacement vertically and horizontally, was ascertained from a set of Floating Drydock General Arrangement drawings. From that I determined the after most spot in the stern I could fit a 2.5" diameter motor-bulkhead at 1/72nd scale, and the ideal height and spacing of the two motor/gearbox drive shafts on the face of that bulkhead to achieve minimal angle on the intermediate drive shaft needed to interconnect the WTC to the propeller shafts.
I was pleased to find, after test fitting the WTC within the Revell 1/72 GATO hull that I had done my homework well and found the offsets to be pretty much in line with what I had graphically worked out on paper. Within the hull I've denoted the stern tube (the packing tube that surrounds the propeller shaft, not a 'torpedo tube' as some of you may think) position in felt pen. A length of brass rod, held with a hunk of clay, stands in for the intermediate drive shaft between the eventual propeller shaft and WTC. No major offset in either plane. So, I'm good to go for running gear (propeller, bearings, stuffing tubes, and intermediate drive shafts) fabrication and installation.
I've taped the kit provided strut bearing-propeller shaft-stern tube part to the hull to demonstrate how close the intermediate drive shaft is to aligning with the propeller shaft. Not bad. Eventually I'll replace this nonfunctioning kit part with a practical 1/8" stainless steel propeller shaft, a bored out and bearing equipped strut bearing foundation, and a scratch-built stern tube.
I fabricated a structural transverse bulkhead to fit between the two kit provided transverse bulkheads in the upper hull halve. Only the top of the hull needed this -- to pull it in about an eight-of-an-inch to counter the outboard warp that occurred when I split the hull.
Cut from the same 3/32" thick styrene type plastic as the kits other parts, this bulkhead was welded in place using Ambroid ProWeld liquid cement. I beefed up the joint with filler rods stretched from kit sprue.
The upper and lower hull halves fit pretty good now, only a quarter inch bow at bow and stern of the upper hull -- easily pulled down to proper shape with a rubber band forward and aft. Later, a capture lip forward and a single screw fastener aft will be all that is needed to hold the two hull halves together nice and tight.
An array of indexing lips within the upper and lower hull will insure that the matting faces of each half stay in alignment -- even on hot July day's at Carmel!
See that 'X' on the side of the lower hull? It and two like it, along the length of the hull, were checkpoints I marked and measured width at -- I wanted to see how much the sides of the hull sprang out when I separated the hull halves horizontally. As it turns out there was only an 1/8" outboard spring at the maximum width point. And that without prior installation of the two kit supplied internal bulkheads! The pent up stress energy relieved itself, as I had feared, by bowing the upper hull half, as I noted above.
Incidentally, the lower hull also warped, but downwards -- the once straight keep (bottom of the hull) now has a concave bow to it. I'll fix that later with plenty of countering Evercoat filler, before I cut in the main ballast and fuel ballast tank flood/ drain holes.