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  #21  
Old 03-10-2011, 03:20 PM
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I was speaking of using structural, NOT laminating, epoxy to harden cones.
Good stuff like Aeropoxy or West System, NOT 50/50 hobby shop stuff that is loaded with fillers to make the mix even for those too challenged to use measuring cups.
REAL epoxy is far stronger than hobby store stuff, which is not all that bad.

My method of 3 coats balsa fillercoat followed by 2+ of Sanding Sealer will not result in a cone anywhere near as hard as an epoxy coated one. Mine look great but are a bit fragile. They will NOT survive bouncing off pavement without mangle marks. Then again, I dont do that to them.
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  #22  
Old 03-10-2011, 04:47 PM
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I've been getting darn good results by brushing thinned FnF over the fins and cone, sanding when dry, then priming and sanding with a dry-sand compatible spray primer. Doesn't make my eyes water, and it's cheap.
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  #23  
Old 03-10-2011, 06:14 PM
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Quote:
Originally Posted by ghrocketman
I was speaking of using structural, NOT laminating, epoxy to harden cones.
Good stuff like Aeropoxy or West System, NOT 50/50 hobby shop stuff that is loaded with fillers to make the mix even for those too challenged to use measuring cups.
REAL epoxy is far stronger than hobby store stuff, which is not all that bad.
Well then, we're more or less in agreement. I want to do that - apply something like a thin formulation of West System epoxy to some nose cones. I think you're right, they'll be much harder than they are with the epoxy that I use now. Being able to sand them smooth is going to be deal maker or deal breaker, but West Systems is known for their large assortment of additives and modifiers, so maybe they'll have something that I can add in to make it easier to sand without significantly weakening it. If it will penetrate well, that will be a bonus too, because it will help somewhat the issue of a soft wood core inside a thin hard shell. Otherwise once something gets through the armor, it has no protection. Toughening up the wood itself in addition to installing body armor is ultimately the best choice if you are going to use balsa, but the most effective and widely available method for doing that takes some time to do the job.

Let me reiterate yet again though that the longer cure times seem to be a factor only with large (e.g., BT-70, BT-80, etc.) balsa cones. With smaller cones, the wait should not be longer than a week at the most, and often more like 2 or 3 days or less. That doesn't seem like an excessive cure time. Many of us wait for similar intervals between paint colors. The builder doesn't have to use wood hardener, of course, but my own anecdotal experience indicates that it is highly effective.
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  #24  
Old 03-11-2011, 04:33 AM
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I like to use thin CA to harden/toughen up cones when I feel the need. Works well for overly soft fins, as well, like the wood that comes in The Launch Pad kits. And the weight penalty is minimal if not nil.
I use epoxy for everything else, though. Holds up a lot better than white/wood glues, especially in the heat we have here. Fins don't sag if the rocket is left on its side.
Works for me!
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  #25  
Old 03-11-2011, 12:30 PM
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Quote:
Originally Posted by Solomoriah
I've been getting darn good results by brushing thinned FnF over the fins and cone, sanding when dry, then priming and sanding with a dry-sand compatible spray primer. Doesn't make my eyes water, and it's cheap.


Yeah, I agree...

I mean, to each his own, if it works for you and you enjoy it go for it, but looking at some of the prices folks have talked about for these sanding sealers and dope and stuff, and the fumes and difficulty in using them, and all that, I'm convinced that I can achieve the same results at less cost and with equal durability and finish with far cheaper and less volatile materials...

BUT, that said, I've never tried the sealer/dope methods either, so I admit that other folks see the benefit of it...

I personally have never seen the need. My results are good enough, especially for LPR. HPR, the other stuff might be called for. I dunno-- no interest in HPR.

Later! OL JR
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  #26  
Old 03-11-2011, 02:21 PM
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Using Balsa Fillercoat and Sanding Sealer has the CORRECT, nostalgic, YE OLDE aroma for building VINTAGE designs.
It has the added benefit that it does not turn the shop into a friggin dust bowl everytime you get a piece of sandpaper within a yard of touching balsa coated with it, unlike Fill-n'-Finish that immediately generates an atom-bomb's worth of dust the second you touch it with any sanding material.
I have less use for ANY water-based finishing material than I have for taking a hot brandin' iron to a dodge-bawl match.
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  #27  
Old 03-11-2011, 09:34 PM
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When I opened a bottle of Aerogloss dope for the first time after becoming a BAR, I had a Proustian moment. I was instantly transported back to the basement of my house in Grand Rapids. All of the cares and regrets of my adult life vanished (temporarily). It was late spring, 1967, I was 13 years old, and I was painting my Astron Alpha, my very first model rocket. Ahh, good times, good times....

To me, that's the real deal, the authentic experience.

I too am hesitant about putting anything as watery as thinned Carpenter's Wood Filler onto raw balsa.

A few weeks ago, someone over on TRF started a thread about brushing his balsa fins with Bondo Glazing and Spot Putty. He used acetone to thin it to brushable consistency. I didn't follow the entire thread but apparently he obtained good results with this technique. I have not tried this myself yet, so don't interpret my mention of it as a personal endorsement.
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Last edited by Mark II : 03-11-2011 at 10:35 PM.
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  #28  
Old 03-11-2011, 09:36 PM
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Hey, I've been using water-thinned FnF for a long time with good results.

The only warning I can give you is to coat both sides evenly at the same time. The only time I've seen warping is when I've not followed that rule.
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  #29  
Old 03-11-2011, 09:44 PM
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Luke, I started out using simple techniques, too, and I still use them in some builds. I got into using more "exotic" techniques to address certain specific issues. Eventually I found that some of them were broadly applicable, and so they became part of my regular toolkit of techniques. I previously mentioned using Delta Ceramcoat All-Purpose Sealer. If you really want to keep things simple, just brush three to four coats of this product onto the balsa. Sand between coats. For a silky smooth final surface, gently wet-sand the final coat with 400 or 600 grit aluminum oxide sandpaper (the black kind). The product has no obnoxious fumes and does not irritate or soak readily into skin, so it can be safely used by children. You can buy it at many craft stores, including Michaels, A. C. Moore and Joanne's Fabrics. It is in the tole painting section.

An even better product in my opinion, and probably the best product of its kind, is Pine Pro Sanding Sealer. Both products fill the grain and seal the wood at the same time, performing two finishing steps with one product. But Pine Pro does a noticeably better job of it, going on more easily with a paint brush, requiring fewer coats to completely fill the grain, sanding smoother and producing a harder surface. The only problem with it is that it only comes in 2 oz. bottles, which don't last long. I can easily kill from one-half to one entire bottle on the nose cone and fins of a BT-20 or BT-50-sized 3FNC rocket. So you have to keep buying it and buying it. You can get the Delta product in quantities up to 12 oz., which is much handier. I reserve Pine Pro for my high-value clones that I want to exhibit that "catalog pic" look. Wet sanding the final coat also produces a glass-smooth surface, even better than with the Delta product. And just as with the Delta sealer, Pine Pro has no unpleasant fumes, does not irritate skin (as far as I can tell) and can be safely used in classes and by Scout groups. This product can be found in hobby shops; look in the section that has the parts for pinewood derby cars.

Neither product produces a particularly durable or nick-resistant coating on the wood (more important for nose cones than for fins), but what you lose in hardiness you gain in simplicity. And if you are working with kids, these are the products to use. Neither one requires any special technique to apply - just brush the product on in even coats, using a synthetic bristle paint brush (so you don't leave hairs in the coat). Both products clean up easily with water and a little bit of soap. Make sure that you clean your brushes while they are still wet, because once either product dries onto the bristles, you'll never get it out.
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Last edited by Mark II : 03-11-2011 at 10:08 PM.
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  #30  
Old 03-12-2011, 09:46 AM
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Quote:
Originally Posted by ghrocketman
I have less use for ANY water-based finishing material than I have for taking a hot brandin' iron to a dodge-bawl match.


YEE-HAW!!!!!

Or should I say HEE-HAW?? Going kinda redneck on us GH?? LOL (ducks and runs)



Later! OL JR
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