#1
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Filling Body Tube Spirals
Hey, Bill!
I recall reading (probably in one of your numerous EMRR reviews) that you filled body tube spirals with thinned "Fill N' Finish." I've already sprayed some tubes with 2 layers of primer, followed by sanding after each coat. What consistency should I make the "filler?" I don't want to get it too thin, because then the water would (obviously) soak into the non-waterproofed body tube. So spill, already. Thanks, buddy! --Jay |
#2
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As long as I've shot a coat of primer on first I've never had a problem. I didn't even have trouble before I adopted the "Prime First" philosophy. I make it the consistency of yellow glue or slightly thicker.
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#3
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Quote:
Jay [and Bill], I know you directed this to Bill, but this is also the method I use. Hope you guys don't mind my intrusion... I actually thin my FNF quite a bit, not quite 'watery thin', but thin enough that I can spread it easily with a hobby brush. Maybe a bit thinner than cream soup. I also sand the tube first until the outer layer of glassine is "flat", or all of the gloss has been removed. You should actually be raising a powder from the surface. This lets the FNF 'bite' into the paper, as well as making the spiral groove lower in profile. The FNF doesn't have so much water in it that it damages the tube, but you do need the compound to work its way into the fibers, and it can't do that when it's thick. Here's where I differ with Bill: DON'T apply this OVER the primer -- it won't adhere as well, because it doesn't have the chance to get into the fibers of the paper, and could fall out of the cracks after it's been painted. You want the FNF anchored to the paper. Don't be afraid to thin the FNF a little more than you think is reasonable. As long as you're not immersing the tube into the FNF tub to soak, you're not going to damage the tube. I suppose if you were using really thin-walled tubes, you might have a problem. But for modern Estes, SEMROC, or Quest tubes (Euclid tubes) you don't have a lot to worry about. Slather it on the whole tube liberally. When this dries fully and you sand it with 220-grit, the tube should now be completely 'stained' to a light tan. This is a good indicator you've adhered to the tube. Depending on how bad the spiral started out, you might need a second "spot application" of slightly thinned, or even full-strength, FNF on those areas before you prime the tube. But this is usually all you need to do before priming. $0.02 worth, with interest... Craig... |
#4
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And don't use the tube as a straw to drink the FNF. It tastes bad and doesn't take the spirals out of the colon as advertised.
Never thought about the possibility of the FNF not reacting well with the "primer first" school of thought. Like I said, I've done both and have never had a problem. I also sand the tube beforehand. |
#5
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My method
I simply add a little water directly to the container of FnF and use a 1" foam brush to stir it up so that I have a layer of FnF about the consistency of house paint. I then paint that onto the fins and spirals. Once it has dried, I sand everything smooth, and repeat the process for any remaining low spots.
Putting water directly into the tub seems to help avoid getting a layer of dry, crusty, FnF. Randal
__________________
Vive Ut Vive |
#6
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Quote:
This brings new meaning to the term "high-colonic," but I digress. I use Elmer's wood filler that is white and comes in a tube. It's already thinner than F'n F. I thin it a little more. You can get absorption into the BT if you are not careful with this stuff. One way to avoid this is to line the spiral on both sides with maksing tape. That's usually too tedious for me, so I run the stuff in with my finger and scrape most of it off with a flat piece of styrene. I usually go over it once more to get the spots that are missed, but that's enough with a coat of primer. Drew Tomko |
#7
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Quote:
That's my method, too. I keep about 1/4" of liquid on top all the time. I stir it up with the brush just before using it, scraping a layer of thicker material up as needed. When it settles down again, you're back to a layer of just water on top... Craig... |
#8
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Think of FNF in the same way as applying a "double glue" fin joint. The first application of FNF [thinned] locks into the fibers of the paper, the second application adheres to the first layer. If you prime the tube first, you've sealed up the gaps between the fibers, and the FNF only has "surface adhesion" to a slick surface after that. YMMV... The primer should be used to seal the FNF, and should be the only surface that the final color coats actually come in contact with. Craig... |
#9
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"Thank ya! Thank ya very much!"
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Thanks so much for everybody chiming in on this! The Semroc ST-5 body tubes I've gotten seem to have a much more pronounced "groove" compared to the classic Estes BT-5 tubes. But since I've recently been trying to discipline my building habits by using Semroc tubes exclusively for some specific building projects... (heavy sigh of resignation) So if I build a version of Pete Alway's "Saturn IV" with Semroc ST-13 and 16 (instead of Estes BT-55 and 60), but still opt for Estes BT-5's... well, you'll know why. Cheers, --Jay "Centuri Guy" |
#10
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Saturn IV: Where to find it
Quote:
Scroll down to rocket #7, where you can download 2 pages of the plans and patterns. --Jay |
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