Best Method for Protecting Balsa?

[AKPilot]

Okay, I've got a brain cramp . . .

What is everyone using to prevent balsa n/c's from taking gouges?

I've got it down on balsa fins, in using paper to reinforce, but am getting a bit frustrated seeing gouges in my n/cs.

Thanks,

 

[Micromeister]

AK:
Don't know about "best" method. but....
Micro to BT-70 Balsa cones get treated with primer and painted, I can't recall the last time i've had any really bad damage to a nc from landing.
Balsa is some pretty amazing material, take a lot of abuse without showing to much. I think I see more damage at public shows where people and/or kids knock stuff of the table or dig a fingernail into the body or NC.

Where are you flying in a gravel pit or rock quary? for Instance I'm still using the same original balsa NC on my Goblin that has more then 50 flight now. the only ding or dent in it is a small hole a youngester stuck a ballpoint pen in it at a show once. It's one of the very first NCs I used only spray primer on as a base & filler material back in the 70's.

Every once in awhile I'll get a bug and try a wood hardener but to be perfectly honest I really don't see any major difference. It does make primer filling the grain a bit quicker. Stinks to high heaven.

Back in the day, and now on special projects I still use Balsa Filler on fins, wings and NCs but not nearly as often. it's a lacquer thinner based material and sticks pretty good as well.

 

[AKPilot]

I fly primarily from a grass field, but on occasion I'll have a rocket land in the parking lot.

On a goonie HJ I had the tip get smashed. And on a Goblin I had a ding put in it.

I thought about using CA and allowing it to wick in.

 

[CharlaineC]

troy I have found that useing elmers fill n finish mixed with white glue smeard on balsa nose cones and allowed to dry then sanding and repeating works great.

 

[JRThro]

I thought about using CA and allowing it to wick in.

That's what I did with the nose cone on my Semroc V-2. I soaked the first 1" or so with thin CA to try to keep the pointy tip from getting knocked off or pushed in. It might work, but since that rocket only has 2 flights so far, there's really no way to tell. The first 1" is definitely harder than the rest of the cone, though.

 

[Gillard]

i use several coats of sanding sealer, the stuff I use is thick, and after a few coats tha balsa i really quite hard - no dents yet.

 

[Pat_B]

CA or yellow glue smeared on work really well. I prefer the yellow glue because it doesn't soak too far into the nose cone, so it stays lighter. It does take a decent amount of sanding to get smooth however.

Light fiberglass such as .75 or 1 ounce would work well too but definitely is a lot of work.

 

[powderburner]

I have used products like thin CA or minwax wood hardener to toughen the outer layer of a balsa NC. For thin CA, I use the cheapo stuff from the dollar store in little tubes. I apply a layer, let cure for a day or two, sand off the raised loose wood fibers, and start with the filler/sand/filler/sand routine. For hardener, I dip the NC and hang up for a couple days and then follow the same procedure.

I do not like using water-based white or yellow glues like some here have suggested. I seem to get a lot of later crazing and cover-layer failure from whatever fillers and paints I put over the top. If these other guys don't have this problem, that's great, I'd just like to learn the secret.

The only way I know to "protect" balsa is to leave it standing in the corner. If it goes outside, it's likely going to get a dent or a scratch. Them's just the breaks-

 

[MarkM]

I use finishing epoxy. One or two coats, sanding between each. Then a high build primer and paint. The finishing epoxy also does a good job of filling the grain of the cone.

 

[Winston]

For small balsa fins, I use the leftovers from used CD labels attached to both sides of the fins. For larger fins, I use portions of Office Depot full sheet white inkjet labels (Item# 612-291).

First, I lay the fin on the label paper (with its adhesive protection sheet still in place) and cut around it leaving an extra 1/4" or so of label around the fin. Do this for both sides by flipping the fin.

Before laying the fin on the label paper with its sticky side up, I lightly sand both sides of the fin with very fine sandpaper to get a smooth surface and then dust the fin off using an acid brush.

After attaching the label to one side of the fin, I lay a thick, metal ruler parallel with and touching one of the fin edges and then press/lay it down. It attaches to the label paper sticking out around the fin. I then use a fresh single-edged razor blade to run along the gap between the metal ruler and the fin edge, putting slight pressure in the direction of the ruler. That gets perfect trims flush with the edge every time.

After the label paper is attached to both sides and rubbed with a finger to make sure it's firmly adhered, I hold a fin so that an edge is sloping about 45% downward and run a light bead of water-thin CA along the edge. Repeat for each edge after the prior edge dries (excepting the edge which will attach to the body tube - keep it bare balsa). Watch that you don't have a run that glues your finger to the fin (don't ask me how I know).

I then sand each fin edge with very fine sand paper.

This sounds time-consuming, but it's actually much faster (and cleaner) than sealing and sanding. Plus, the paper/balsa/paper sandwich is a very strong composite that's far more rigid than the original naked fin and easily takes a great finish.

 

[kjohnson]

Okay, I've got a brain cramp . . .

What is everyone using to prevent balsa n/c's from taking gouges?

I've got it down on balsa fins, in using paper to reinforce, but am getting a bit frustrated seeing gouges in my n/cs.

Thanks,

I use appropriate length shock cords.

kj

 

[troj]

Okay, I've got a brain cramp . . .

What is everyone using to prevent balsa n/c's from taking gouges?

I've got it down on balsa fins, in using paper to reinforce, but am getting a bit frustrated seeing gouges in my n/cs.

Try wicking thin CA into the nosecone. The challenge here is that it produces a hard outer coating, but the innards remain soft and juicy -- kinda like an egg. Break the shell, and the soft, gooey center is still there.

I saw a recommendation of Elmer's Fill & Finish; my experience is that it's a great filler, but not very durable, and still dents easily. Another person recommended epoxy, which I think would work even better than the CA, although it will add more weight.

If you go with epoxy, use a laminating resin that's fairly thin, and warm both the nosecone and the epoxy, to help it soak in more.

-Kevin

 

[Mikus]

I'm starting to like the Minwax Wood Hardener that Micromeister recommended a few posts back.

The real test will be getting the fins on the Super Big Bertha I'm working on back in one piece after landing.

 

[m85476585]

I didn't like Minwax wood hardener on the few things I used it on. It made the wood a lot harder to sand, but not much more resistant to dents.

 

[atlcdp]

I have four balsa nose cones that I want to treat before using them in a custom build. I was really hoping for a consensus.

I learned the balsa/label trick at a launch one day and tried it out. It works great! The laminate makes the fins much stronger. Keep in mind that it is still Balsa wood. If you have fins that land first, like on a Big Bertha or an Estes Alpha III, they are still in danger from a hard landing.

 

[Marc_G]

I have four balsa nose cones that I want to treat before using them in a custom build. I was really hoping for a consensus.

Looking for consensus? Wrong forum for that! :wink: we all have our own funny little ways of doing things!

 

[luke strawwalker]

I have four balsa nose cones that I want to treat before using them in a custom build. I was really hoping for a consensus.

I learned the balsa/label trick at a launch one day and tried it out. It works great! The laminate makes the fins much stronger. Keep in mind that it is still Balsa wood. If you have fins that land first, like on a Big Bertha or an Estes Alpha III, they are still in danger from a hard landing.

Honestly I think your best bet is to treat them with ultra-thin CA glue... allow it to soak in until it will take no more... this is the standard procedure I give mine-- works good. Doesn't make them bulletproof, but then NOTHING WILL.

I then brush on a coat of thinned Elmer's Carpenters Wood Filler (CWF) and sand that out with 220 followed by 400 grit, give it a few coats of primer, allow to dry, then sand again with 220 followed by 400 grit, and damp sanding by dipping the 400 grit wet/dry in a bowl of water and shaking off the excess... works great. Balsa cone comes out looking like plastic, it's so smooth and silky-- ready for paint.

Later! OL JR

 

[AfterBurners]

Honestly I think your best bet is to treat them with ultra-thin CA glue... allow it to soak in until it will take no more... this is the standard procedure I give mine-- works good. Doesn't make them bulletproof, but then NOTHING WILL.

I then brush on a coat of thinned Elmer's Carpenters Wood Filler (CWF) and sand that out with 220 followed by 400 grit, give it a few coats of primer, allow to dry, then sand again with 220 followed by 400 grit, and damp sanding by dipping the 400 grit wet/dry in a bowl of water and shaking off the excess... works great. Balsa cone comes out looking like plastic, it's so smooth and silky-- ready for paint.

Later! OL JR

JR - Would you use the same method on wings and fins. I might use your method on my Interceptor E build, rather than trying skin the fins. I like aero gloss dope sanding sealer a basla filler.

 

[luke strawwalker]

JR - Would you use the same method on wings and fins. I might use your method on my Interceptor E build, rather than trying skin the fins. I like aero gloss dope sanding sealer a basla filler.

Personally, I paper the fins/wings... just SO much stronger, and it makes finishing a snap...

I'd paper the nosecone if it weren't for the compound curves... paper doesn't do well with compound curves... (well, it CAN, if you're a papermodeling artiste... as viewed on the paper modelers forum... which I'm not).

Later! OL JR

 

[Marc_G]

FWIW I use the "paper with CA" method these days. Light tack printer paper with spray adhesive, press fin on, trim with knife, soak CA through. You can use label paper if you don't want to spray the adhesive. Gives super smooth, super strong fins.

 

[AfterBurners]

FWIW I use the "paper with CA" method these days. Light tack printer paper with spray adhesive, press fin on, trim with knife, soak CA through. You can use label paper if you don't want to spray the adhesive. Gives super smooth, super strong fins.

After you press on the paper do you soak the entire fin or just the edges??

 

[Marc_G]

After you press on the paper do you soak the entire fin or just the edges??

Press on, trim, soak entire fin using q-tip to wipe it around. After cure, very brief sanding (more of a polishing) with 320 grit. The sanding is super easy and just takes a minute, resulting in a plastic like surface. I got this overall method from CaveDuck... see a thread I did here:

https://www.rocketryforum.com/showthread.php?48846 (see post 5)

I've used this in several builds since, with always great results. These days I don't do the "taco" method shown above as much as separate pieces of paper on each side, but it works fine. Depends on the fin profile you wish to achieve.

Here's another example:

https://www.rocketryforum.com/showt...atisfying-unrequited-love&p=514471#post514471

 

[AfterBurners]

I might try it on my current build, but before I do I'll see how it works on a few scrap pieces of balsa. I have 3M spray adhesive, but not the Super 77. I had a can blow up on me (go bad) and 3M said they would replace it, but they didn't have it in stock ...go figure and this was months ago. I'll have to give them a call and it was a full can.

 

[Marc_G]

Use whatever spray adhesive you have, or use label paper... it will be fine. I like the sprays because I can do a super light tack. My worry with label paper was there would be a gummy layer under the paper surface over the wood, that might interfere with the CA soak-through. This problem has never occurred in my hands... seems thin CA is a decent solvent and goes right through.

My general preference for formula 77 spray for most applications is that the bond can usually be broken later and the (whatever) removed. The other formulation is more permanent. In our fin papering exercise, this isn't really a consideration. So either spray is fine.

Note: I like to paint with airbrushed acrylics... for me, the hardened CA-papered surface is ideal. A non-hardened surface (from white glue papering techniques) would be OK but less than ideal. However with lacquers, and maybe enamels too, which impart surface hardness of their own, the pre-hardened surface doesn't offer as much of an advantage (though, there is no real disadvantage).

 

[AfterBurners]

Use whatever spray adhesive you have, or use label paper... it will be fine. I like the sprays because I can do a super light tack. My worry with label paper was there would be a gummy layer under the paper surface over the wood, that might interfere with the CA soak-through. This problem has never occurred in my hands... seems thin CA is a decent solvent and goes right through.

My general preference for formula 77 spray for most applications is that the bond can usually be broken later and the (whatever) removed. The other formulation is more permanent. In our fin papering exercise, this isn't really a consideration. So either spray is fine.

Note: I like to paint with airbrushed acrylics... for me, the hardened CA-papered surface is ideal. A non-hardened surface (from white glue papering techniques) would be OK but less than ideal. However with lacquers, and maybe enamels too, which impart surface hardness of their own, the pre-hardened surface doesn't offer as much of an advantage (though, there is no real disadvantage).

I'm looking forward to trying this technique. I found some balsa laying around that I can experiment with. I'll post my results later.

 

[AfterBurners]

I just had to try this and I want to thank Marc for sharing this technique. I took a scrap piece of balsa and use some spray adhesive to tack down the copy paper. I pressed it down and waited a few minutes and evenly spread CA over the entire surface.

I then sanded it with 320. As Marc mentioned this actually polishes the surface and makes it very smooth. The CA acts like a shield to keep you from sanding through the paper

I used some Rustoleum gray primer and shot a coat of primer. I didn't bother to sand the primer and then I spray a coat of red paint. I just wanted to get an idea of what the results would look like. You can see the paper edges, but of course on my build I'm doing I would go back and fill those in with FnF or spot putty glaze, whichever works best. I also didn't wet sand the sample piece...just a lick and a promise.



What I like about this method it really isn't messy. You just have to take your time and spread the CA evenly and on large piece of balsa that might take some time. The strength is just as strong as using white glue and copy paper without having to deal with any bubbles or possible tears in the paper. Also you don't have to worry about the fins warping. I never had any fins warp using white glue, because I laid it down real thin.

There's no right or wrong way to paper the fins...it's finding the method that works best. On my Interceptor "E" I'm not too thrilled about the strength of the wings, so this method should make the wings and fins sturdy without adding a lot of weight.

 

[Marc_G]

Looks like you've got the touch!

Credit where it's due: CaveDuck turned me on to this technique. I certainly didn't invent it!

 

[AfterBurners]

Looks like you've got the touch!

Credit where it's due: CaveDuck turned me on to this technique. I certainly didn't invent it!

Than many thanks to CaveDuck where ever he might be. I recommend this system to anyone out there. I just tried snapping that balsa that is pictured. Took some force to do it. I'm sure it will strong enough to handle any bad landings.

 

[Marc_G]

Another benefit to the technique: in practice, typically the fin is positioned over the paper and pressed down such that there is some paper overlap. This paper is extremely easy to trim with a hobby knife, because it isn't soaked with glue or anything at that point. It allows nice close trimming of the paper right up to the edge of the wood.

 

[AfterBurners]

Another benefit to the technique: in practice, typically the fin is positioned over the paper and pressed down such that there is some paper overlap. This paper is extremely easy to trim with a hobby knife, because it isn't soaked with glue or anything at that point. It allows nice close trimming of the paper right up to the edge of the wood.

That's true. I need to round the edges first on my wings / fins before papering them, but I can see how much easier it is to use this method.