Scratch-built 1/96 Oscar II

[KevinMC]

G'morning guys,

I'll start by adding

G'morning guys,

I'll start by adding a photo that would have saved me about 400 words above- here's the setup I use for marking the center line on appendages]http://www.subcommittee.com/forum/fin_marked.JPG[/img]


I mentionned a little about vac-bagging before, I'll explain a little further here. With small parts and glass cloth that doesn't otherwise want to follow the contours of those small parts, the vac-bag is a great tool. It's really as easy as placing the cloth over the item to be glassed, saturate the cloth and stuff it all in a bag. As can be seen here I'm using nothing more than an ordinary Zip-loc sandwich bag.




Once the resin has cured this is how it looks when it comes out of the bag.




Finally, the extra cloth is trimmed away...

[KevinMC]

Mike- I've thought about using

Mike- I've thought about using WPU many times, but didn't have the nerve to add that to the list of things that I'm learning about on this project. One thing that I have found though is that if you don't use any glass cloth it's very easy to sand the resin down so thin it causes "thin spots" in the surface. Sometimes when this happens I find the result is a little bulge that doesn't want to be sanded away because as soon as any pressure is applied by the sander it gets "pushed in". Generally I've found once that happens the only cure is to cut out the weak spot, dig out a bit of the foam underneath and back fill with an epoxy/microballoon sludge.

[mylo]

Kevin,

Great technique, the vacu-bag.

Kevin,

Great technique, the vacu-bag. I take it the bag itself doesn't get sucked to the part and stuck there ? Why doesn't that happen ? Is it because the resin will only stick to the cloth ? What is that machine that sucks ?....I mean....the vacuum, what is that ?

....questions, questions, questions.

Myles.

[KevinMC]

Myles- The "sucker" is a

Myles- The "sucker" is a comercially available vaccuum pump, made specifically for this purpose. Under vaccuum, the bag does get sucked right down onto the cloth. Actually, if it didn't there wouldn't be much use in this technique since it's that direct contact that presses the cloth down onto the surface underneath it. The smooth surface of the plastic won't allow the epoxy to adhere to it, so when it's all set up all you have to do is peel the bag away from the surface.

Using a sandwich bag was an experiment for me, normally I use heavier plastic but the bowplanes were such a small part I wanted to try using a smaller bag. I'd call it largely successful, although the plastic used for the bag was almost a bit too thin- I say this because the plastic was actually drawn down into the weave of the cloth by the vaccuum. (If you look carefully at the last of the bowplane pictures you can just make out the texture of the cloth.) Regardless, it was a very convenient way to do things and I'll definitely use Zip-locs again for these smaller parts.

[KevinMC]

More updates- I've intalled the

More updates- I've intalled the "web" that bridges between the two prop fairings. Since it's basically a flat plate I elected not to build it in until after the hull was glassed. Not having this part in place has made it much easier to apply the glass cloth to the prop-spines, and subsequent sanding of same.

I made the web from 0.030 G-10 material, which is great stuff to work with. Once cut to shape, the web pieces (top and bottom) were CA'd into place. I've also begun to fill the area in using the "Icing" autobody filler.







And here's a stern shot with the fin in place to check the fit.

[KevinMC]

I've also done some filling

I've also done some filling to the bow area. When putting the close-weave glass cloth down around the bow area I found the only way to get it to sit down properly was to make many cuts in it, but this resulted in many bulges. Although I've sanded them down as best I could, the bow just didn't have the right "feel" to it. Once again, Icing to the rescue! Don't confuse this stuff with Bondo by the way, it's a whole other thing. Great for area filling (as I'm doing here) Icing has the consistency of toothpaste so its almost thin enough to be used as spot-putty. Unlike spot putty, this stuff is polyester based so you can also lay it on thick and still have it kick off in less than 15 minutes.

[KevinMC]

Almost forgot- Now we get

Almost forgot- Now we get to the real reason why I had the stack of business cards in my "tools" photo. In addition to being useful for spreading epoxy on the glass cloth, they're also great for shaping the Icing to catch the contour of the hull. By using a thin stack of cards to spread the Icing, bent to catch the round shape of the hull, lows are quickly filled in without leaving any big wealts on the hull that will need to be ground away later. BTW, once cured I'm still sanding with light pressure and 80 grit paper.

[mylo]

Kevin,

Excellent tips and info

Kevin,

Excellent tips and info on "sub icing". Can you include a photo of the container in your next post ?

Myles.

[KevinMC]

Myles- Have a look in

Myles- Have a look in this morning's "web-between-spines" shots. The Icing is the white tube in the the upper left corner. (It's also in the photo I took near the beginning showing the materials I was going to be using.) It's really good stuff, but you'll probably only find it at better auto repair stores. (For the Great White Northern folk, you won't find this product at Canadian Tire. I got mine from Car Quest.)

[KevinMC]

Well, it's been a busy

Well, it's been a busy couple of days but I'm finally back to post more photos. After adding filler to the bow and carefully sanding to shape, I wanted to check things to be sure I didn't have any bulges. Since there are supposed to be some scribed and painted lines running in several directions, I was afraid that a bulge might slip through unnoticed until I went to finish the model, by which time it would be way too late to correct things. I'd considered drawing lines on the bow with a pencil to verify the shape, but if I had to sand anything away I'd immediately lose my reference line. Some thought yielded the following solution]http://www.subcommittee.com/forum/bow_check_1.jpg[/img]








Now all I have to do is look carefully at the bow from straight in front and look for good left-to-right symmetry and any "bulges" in the beam.

[KevinMC]

I also managed to get

I also managed to get some priming in. Here's the fin, and I've also placed (but not yet glued) the piece at the tip that I machined to replicate the towed array housing. I'll glue this into place once all the work on the hull is done to ensure that it sits dead level with the upper surface of the hull.




And here's the fin with the rest of the appendages, ready for prime.




Finally, here's the hull again having seen it's first coat of primer.

[guillermo pelaez]

Kevin,
The Oscar is looking great!

Kevin,
The Oscar is looking great! excellent descriptions. And the LASER thing... most clever, to say the least...
Keep them comming!
Cheers

[tupolev]

Kevin,

Your Oscar looks great !!

Kevin,

Your Oscar looks great !!
This this most derised kit for my, an Oscar II .

Thany you for share with us your building. It's very interesting.

Regards.

Tupolev

[steveuk]

..appreciate all the time and

..appreciate all the time and effort you are spending taking pics and uploading for us. Very interesting seeing it come together and how you do it.

[anonymous]

]http://gantu.de/OscarII/OscarII_05.jpg
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http://gantu.de/OscarII/OscarII_09.jpg
http://gantu.de/OscarII/OscarII_10.jpg
http://gantu.de/OscarII/OscarII_11.jpg
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Gantu

]http://gantu.de/OscarII/OscarII_05.jpg[/img]






Gantu