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Old 03-23-2011, 06:45 PM
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blackshire blackshire is offline
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Default Cone hardening methods?

Hello All,

I'm getting ready to order a few parts, including various BT-5 conical balsa nose cones, to build a few scale and scale-like models of test vehicles and sounding rockets such as the Argentine Tronador I and several Indian sounding rockets.

What is the most effective way to harden conical balsa nose cones (particularly to strengthen the nose cone tips)? I know that thin CA (or maybe even thin epoxy) could be "wicked" into the wood and then sanded when cured, but for pulmonary reasons I'd prefer to avoid them. Would white glue and/or yellow glue (perhaps thinned a bit with water) work? Also, are there any carpenters' wood-hardening products that would work on balsa?

Many thanks in advance to anyone who can help.
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Last edited by blackshire : 03-23-2011 at 06:48 PM. Reason: This ol' hoss done forgot somethin'.
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  #2  
Old 03-23-2011, 07:06 PM
j.a.duke j.a.duke is offline
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Quote:
Originally Posted by blackshire
Hello All,

I'm getting ready to order a few parts, including various BT-5 conical balsa nose cones, to build a few scale and scale-like models of test vehicles and sounding rockets such as the Argentine Tronador I and several Indian sounding rockets.

What is the most effective way to harden conical balsa nose cones (particularly to strengthen the nose cone tips)? I know that thin CA (or maybe even thin epoxy) could be "wicked" into the wood and then sanded when cured, but for pulmonary reasons I'd prefer to avoid them. Would white glue and/or yellow glue (perhaps thinned a bit with water) work? Also, are there any carpenters' wood-hardening products that would work on balsa?

Many thanks in advance to anyone who can help.



Check out this thread on TRF about Teamwork Filler.

I think it might be the solution for which you are looking.

I was hoping to get the ingredients to test it this past weekend, but the washing machine had other ideas....

Cheers,
Jon
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Old 03-23-2011, 07:57 PM
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blackshire blackshire is offline
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Quote:
Originally Posted by j.a.duke
Check out this thread on TRF about Teamwork Filler.

I think it might be the solution for which you are looking.

I was hoping to get the ingredients to test it this past weekend, but the washing machine had other ideas....

Cheers,
Jon
Thank you, Jon! This 50%/50% (by volume) mixture of Minwax Wood Hardener and Bondo Spot Putty sounds promising. The replies on that TRF thread indicate that while balsa wood impregnated with cured Teamwork Filler (tm?) isn't as hard as CA-impregnated balsa (which is okay by me, as I'm not looking to simulate annealed steel nose cone tips), it *is* easier to sand, which sounds appealing to me. It apparently contains MEK (Methyl-Ethyl Ketone), which enables it to penetrate well into balsa wood, but (probably because I've developed a tolerance to it by using so much Testors liquid plastic cement over the years) MEK doesn't bother me.
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Old 03-23-2011, 09:14 PM
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sandman sandman is offline
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Quote:
Originally Posted by blackshire
Hello All,

I'm getting ready to order a few parts, including various BT-5 conical balsa nose cones, to build a few scale and scale-like models of test vehicles and sounding rockets such as the Argentine Tronador I and several Indian sounding rockets.

What is the most effective way to harden conical balsa nose cones (particularly to strengthen the nose cone tips)? I know that thin CA (or maybe even thin epoxy) could be "wicked" into the wood and then sanded when cured, but for pulmonary reasons I'd prefer to avoid them. Would white glue and/or yellow glue (perhaps thinned a bit with water) work? Also, are there any carpenters' wood-hardening products that would work on balsa?

Many thanks in advance to anyone who can help.


For over 40 years I have been using white Elmer's glue on my nose cones. Straight! squirt it right out of the bottle onto the nose cone and brush it smooth. Let it soak in and dry. Sand with 220 grit then 2 coats of primer.

It gives me a plastic smooth finish.
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Old 03-23-2011, 09:49 PM
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Mark II Mark II is offline
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BT-5 sized balsa nose cones aren't all that prone to incidental damage to begin with, most likely because the rockets that use them are pretty low in mass. I don't think that any of the more advanced methods of balsa hardening are really necessary for them because they don't need such strong armoring. Something like Delta Ceramcoat All Purpose Sealer or Pine-Pro Sanding Sealer ought to work fine for sealing, filling and hardening the wood. These products are water-based and don't emit any noxious fumes. They don't really penetrate into the wood all that much, but as I said I don't think that is really needed for parts at that scale. A surface treatment really should be enough. This is usually what I use on my smaller (under BT-50-sized) nose cones.

If you want to use something that is a bit more penetrating and you can handle the fumes, butyrate dope-based fillers and sealers (such as Aerogloss) work well, too. Their primary purpose is to prepare the surface of the wood, but they do penetrate easily into it and after they are fully dry they do have an incidental effect of hardening the surface a bit. Dope products won't harden balsa to the same extent as the full-bore hardeners will, but they'll probably be all that you need. I use dope filler and sealer on my smaller-pattern fins without any other reinforcement, and they do a fine job of protecting the surface.
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  #6  
Old 03-23-2011, 09:58 PM
Bravo52 Bravo52 is offline
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I use the Minwax Wood Hardener. Let it dry and hit it with two coats of filler primer and it is smooth as plastic.

When I first started to build plastic models, I was hesitant to go at it with real coarse sandpaper. Once I learned to hit with 220 then 400, things started to pick up. What I've learned with balsa is to not "over sand" it.

Mark, I do like the idea of water based sealer/hardeners. I'll have to give it a try.
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  #7  
Old 03-23-2011, 10:02 PM
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I dip mine in future.....let it soak in and dry.
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Old 03-23-2011, 10:10 PM
stefanj stefanj is offline
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MixWax Wood hardener to begin with. Unlike epoxy, it penetrates. It does swell the wood a bit, but then I was going to sand it anyway, right?

Hmm, I bet Future would work. Not as penetrating as the wood hardener, but much less obnoxious.

Sometimes I'll brush on a very thin coat of finishing epoxy, but not often.


Sometimes I put a flat-headed pin into the tip of a nosecone with a very narrow tip. Just push it right in until the head of the pin caps the nose cone. I cover this with epoxy + microballoons and sand to make a smooth transition.

Something I often do, to cones and balsa bulkheads: Add an inch or two long coupler to the cone's shoulder. This prevents "cranking" and thus protects the top of the body tube. I chip a groove in the rear of the balsa shoulder and slip the coupler over this. Sometimes I epoxy strips of fiberglass on the inside of the coupler to the bottom of the shoulder.
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Old 03-24-2011, 03:18 AM
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blackshire blackshire is offline
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I thank you all very much for your replies! I think I'll first try un-diluted Elmer's glue as Sandman mentioned. After sanding, it should hold lacquer or enamel (or even acrylic) spray paint fine. Since some of the nose cones are pretty sharply-pointed, their tips might be more prone to breakage or "erosion" from point-down landings (even in grass, with properly-deployed recovery systems) due to their small size.
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http://www.lulu.com/content/paperba...an-form/8075185
http://www.lulu.com/product/cd/what...of-2%29/6122050
http://www.lulu.com/product/cd/what...of-2%29/6126511
All of my book proceeds go to the Northcote Heavy Horse Centre www.northcotehorses.com.
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  #10  
Old 03-24-2011, 09:22 AM
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ghrocketman ghrocketman is offline
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Finishing materials devoid of "noxious" organic solvent fumes are NOT legitimate finishing methods, no matter what anyone else tries to claim.
Chances are if the finishing method meets Commiefornia VOC compliance, it SUCKS !

Multiple coats of thinned (at lease 50% thinner to sealer ratio) Aero Gloss Sanding Sealer will result in a HARD balsa nose cone. Small cones can be dipped directly into a can of the thinned mixture and allowed to soak for a few minutes.

Epoxy/Microballoons is however much harder and more durable.

Have zero experience with the Minwax wood hardener, but others really like it. I do know it has an obnoxiously long dry time though.
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