R/C'ing the Revell 1/72 GATO Class Static Submarine Kit, Part-7

A Report to the Cabal:

Time to fix the warts: the imperfections as a result of warps and slight misalignments between glued sections. And there are the inevitable open seams between glued parts that need filling and contouring. The big filling job was at the bottom of the hull, where it had bowed up, into a concave warp instead of straight line, along the keel line. Lots of filler needed there.

While working the bottom of the hull I added strips of brass to form a 'hard keel' -- I'm a 'drive 'em hard and put 'em away wet' sort of r/c vehicle operator and my models make hard contact with pool bottoms and sides with sickening regularity.

I'll show you some abrasion tool making tricks and means of minimizing the area of application of fillers needed to fill part seams.

Let's go ....

The upcoming filler work will demand of you some precision sanding and filing. For the gross sanding you'll use sanding blocks, and as the work get more precise, you'll need to transition to something with a bit more control and ability to negotiate tight areas on the model, something like these special two-sided pieces of stiff sandpaper. I make double-sided sanding squares from #100, #240, and #400.

You make these things by simply folding over a piece of sandpaper that you've place CA adhesive on its inboard paper side, clamp it tight till the glue cures hard, then trip the edges with scissors. To the left you see a clamp I've made from a sanding block and the edge of the work table, a spring loaded clamp does the ... er ... clamping action. The work goes quickly: while one sanding square is clamped, your trimming another with scissors. I had all these knocked out in about five-minutes.

It's a good practice to have all you tools and consumables ready before getting into the filler application and abrasion tasks. Getting fresh sanding squares ready for the job is just one of those tasks. Not the freshly applied CA laid onto the paper side of this #100 grit sandpaper.

The edges of the sanding squares are trimmed with scissors with specific shapes, each suitable for a specific sanding chore on the model. As you use these things and an edge gets fouled with plastic and filler, you simply snip off that edge with the scissors, revealing a fresh cutting edge -- these sanding squares have great utility and get into a lit of tight spaces, and they last a long time.

The filler applied to the matting faces between the two hull halves made up the lost kerf when I went at the hull with the Dremel circular saw. Now is the time (after attaching an array of indexing tabs within the hull, top and bottom) to check the fit; how tight the seam between the two hull halves is. Where necessary I add filler to a mating face or abrade it away with file and/or sandpaper, you see those tools (see the sanding square?) on the table.

A sure fire means of checking line straightness -- long ago taught to me, along with many other neat tricks, as I assisted this old Norwegian house build -- is to use one eye to sight down the line. Any variance from 'straight' is apparent when you do this. Where variations of straightness were found I marked the model and then either filled or abraded to straighten the separation line between upper and lower hull.

The ugly squint you see me demonstrating here is a vital ingredient in this process. Practice it in front of a mirror till you get it right ... you know it's right when it sends small children off screaming and startles adults into involuntary bowel release.

The union between bow and stern piece to the main hull is pretty good. But, there is a bit of a concavity at these unions that has to be filled with Evercoat Metal Glaze. Same situation with the bow piece, but of a lesser magnitude. The other seams on this kit are very tight and the adjoining areas of those seams of correct contour.

You never apply catalyzed filler to unprepared polystyrene plastic -- you have to rough up the surface, give it some 'tooth' before bladding, brushing, or stippling the filler in place. Use of a #100 grit sanding square was perfect for this chore. The triangular shape of the scratches on the hull you see here was dictated by the distortion observed: at the seam between hull halves I found that the top overlapped the bottom, so I had to build up the bottom. I started by scratching the areas of the lower hull beneath the seam for a distance equal to the length of the overlap. And I brought the scratch down to the point where the concavity observed between main hull and after hull piece terminated. The scratched portions of hull guide me as I apply the filler.

I use this disposable paper palette bought from Mattos Inc. to hold the filler and cream-hardener and to mix them. Application tool is either a forefinger, putty knife or stiff brush. The X-Acto blade is there to chase out filler that gets into the seam between the two hull halves before the filler hardens -- don't want to glue them together now!

The catalyzed filler was applied to the scratched areas of the model with the putty-knife. The areas between stern tube and hull were filled using the stiff paintbrush --there's a tight radiused fillet around the stern tube, and the brush is a great tool for achieving this. Of course, care was taken to immediately clean the brush in lacquer thinner as well as the putty-knife and X-Acto blade.

Initial sanding was done with a #100 block, I then shifted to the #100 sanding squares working around the stern tube, then a soft-block (a hunk of foam) sanding with #240. Using a #240 sanding square around the stern tube. Knocking down the major sanding marks and dusting down was done by some swipes of '0000' steel wool.

When properly prepared, styrene plastic is most receptive to polyester based fillers, such as the Bondo and Evercoat brands. Some idiots claim that Bondo like fillers on model submarines don't work because this material absorbs water, swells, and flakes off -- these people are full of shit! I've been doing it this way for nearly twenty years and my boats are holding up just fine ... thank you very much!

I had to control, exactly, the placement of the fillers used atop the upper hull. You have all that glorious detailing up there on the deck, you don't want to clobber it with carelessly applied Metal Glaze. It's a simple matter to use low tack masking tape to protect the adjacent areas of a seam you need to fill. Such is the case in the picture above, the fine engraved and raised deck detailing well protected by lengths of masking tape.

Filler has been applied to the seams. Note the protective use of masking tape. Initial block sanding is done with the masking still in place.

The masking tape removed, you see the filler on the superstructure. No problem working the sides here, but as I went about sanding down the deck area, with all that engraved and raised detailing, I again applied masking tape, but this time to prevent scratching of areas I don't want to touch. Sanding blocks and double-sided sanding squares made quick work of this very localized filler application.

I've applied fresh masking tape to the areas either side of the applied filler. This is the seam work done between the after and middle deck pieces. The tape prevents abrasive damage to surrounding areas as I knock down the excess filler at the seam line.

Using a big straightedge to check the depth of the concave warp at the hulls keel. About a quarter-inch deep at the center! I couldn't let this go -- I abraded the area, then slathered on massive amounts of filler, and worked it to get the correct contour at the bottom of the hull. Took about a half-hour to do that. Not bad.

Note that I've not installed the two bilge keels -- having those appendages hanging out during all this work would have been an impediment to the work. The instructions call for their assembly as step-one. I won't put them on till I'm ready for primer ... waaaaayyyy down the road.

Here I've completed the filling and abrading work to get the hull contoured correctly at the keel. Note that I'm installing some narrow brass strips to represent the models 'keel.'

I'm rather dangerous (foolish?) in the water and quite often will bounce the submarine off the bottom. If you examine the bottom of my model submarines, my above statement is driven home!

The metal keel strips will be faired in by first adhering them in place with epoxy laminating resin, then filler -- by time I'm finished you won't be able to discern the models original plastic keel plate from the brass one I'm installing here.