Balsa prep/sanding

I am in the final stages of prep for my Vintage Der Red Max. (Balsa N/C and I had the cut the balsa fins myself, I have had the kit for at least 20 years).

After finishing the build I used the diluted elmers wood filler over the entire rocket. Then sanded everything smooth and did the wood filler for a second coat. I sanded that all the way down to 600 grit and then I applied a coat of water based sanding sealer. Sanded that down to 1000 and did a second coat sanding it to only 400 based on the recommendation of the primer I am using. (I think, maybe I saw that somewhere else). When I went to my shed to apply the primer the rocket was smooth and looked great. As I was applying the primer I noticed deep scratches in the nose cone and one of the fins. I am not sure how they got there and I know they were not there when I finished sanding. I suspect that it happened when I set the rocket down on the outdoor work table I have before I opened the shed. It was pretty windy and it fell over and slid a little on the rough surface of the table. I had hoped that all the prep work would have made it a little more durable than that. Am I doing something wrong? Is it always going to be this soft or will the paint help? I used the wood filler to fill in all the scratches, and I am back to square one.

Suggestions?

First of all I think you are making more work than necessary. I don't know why you would coat the whole rocket with diluted wood filler. Just concentrate on the spirals or use spot putty glaze. I've always had good luck with Aerogloss sanding and balsa filler. I like using thin CA on the nose cone. Put on a few coats and sand between each coat...you get amazing results. The first coat I sand with 220 then 320 and 400 and than use high build primer. Sand until smooth and repeat if necessary...shoot your top coat after that

I do pretty much the same thing: CA to harden balsa parts, particularly nose cone.

For surface dings, scratches, spirals: Either wood filler or 3M glazing putty for spirals and such. Sometimes Tamiya putty, depending on my mood, but all these fillers are just used for surface imperfections.

Going above 400 on anything before the finish paint is probably a waste of time, though I applaud the effort!

Remember: we like pictures! Show us how it turns out.

Welcome to the forum.

Marc

Yes I forgot welcome to the forum and as Marc above mentioned throw some pictures up we like pictures....

I use the diluted wood filler on balsa and in my experience it doesn't add any surface protection at all. The thin CA coat is an easy, popular, and proven way to stengthen balsa. I just use whatever cheap dollar store super glue I have at hand. Another tool in the tool box is epoxy. I did this on a build a few years back: https://www.rocketryforum.com/showthread.php?49317-Balsa-nose-cone-treatment

At the end of the day you still have a piece of wood that will show some scars when flown. And that's cool by me.

Just an FYI when putting thin CA on the nose cone. You can use a q-tip but what I found that works best is to make a small puddle of CA on a zip lock baggy. Starting with the tip of the nose cone rotate it in the CA and work your way down to the base of the nose cone. Make sure you mask off the shoulder. By doing it this way it doesn't get on your fingers and you don't waste as much CA. You also get a very even coating. Sand with 220 apply another coat and go to 320 and that should be enough prep for the primer. Any imperfections go over with spot putty glaze and fill.

You need to keep in mind that the base material (balsa) is a soft wood. Soaking in as much thin CA as the wood will absorb will only help with minor scratches and dings. CA and filler also aids in a very smooth painted finish on balsa but will not make it anywhere near dent and gouge proof.

I like to make my rockets look extra good for the first flight, it's down hill in the looks department after that!

bradycros said:

You need to keep in mind that the base material (balsa) is a soft wood. Soaking in as much thin CA as the wood will absorb will only help with minor scratches and dings. CA and filler also aids in a very smooth painted finish on balsa but will not make it anywhere near dent and gouge proof.

I like to make my rockets look extra good for the first flight, it's down hill in the looks department after that!

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You're right Brady...one or two flights they good after that they just hold rocket motors

Thanks for all he suggestions. Another question from a newbie - What is CA?

I decided to coT the whole rocket with the wood filler because the body tube got squished a little while it was in storage. I had hoped it would help hide some creases. It did help, it's not perfect but it's pretty good.

I only get a few hours a week to work on it so it is a slow process but I will defiantly post pictures.

Here is a picture of how it looks today

CA is usually the water thin variety of Super Glue in this instance the thin variety is best.

warix said:

Thanks for all he suggestions. Another question from a newbie - What is CA?

...

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CA is short for cyanoacrylate glue, AKA super glue. There are many different brands and formulas (ex. foam safe) with consistancy ranging from thin, medium, thick to gel. Like I said, dollar store brand thin (or any thin you prefer) works for stiffening balsa.



BTW I keep a tube of gel in the range box for quick field repairs. Indispensible stuff.

warix said:

Here is a picture of how it looks today

View attachment 262564

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Nice one.

Warix, if you have a Hobby Lobby near you, check out their models glue section. You will find some bottles of yellow / green / pink labeled superglue (CA). The pink label bottles are the thinnest and that's what I use the most for hardening balsa.

That said, I think they are going through a reset of the labeling so it may no longer be the pink bottles you want. Just look for the stuff that says Thin (As opposed to medium or thick).

Here's some links to the finishing schedule I follow:

https://modelrocketbuilding.blogspot.com/2013/04/my-finishing-schedule-tips-part-1.html
https://modelrocketbuilding.blogspot.com/2013/04/my-finishing-schedule-tips-part-2.html

Everybody has their own methods of finishing. These are what works for me.
These blog posts are only suggestions. You'll come up with your own tried and true methods.

Ok so CA is super glue. I think I knew that but it has been a while since I heard it called that. I never knew that you could apply it to balsa to make it stronger. Honestly it kinda scares me a little. I have never had good luck with super glue. I get it everywhere when I use it. I am having visions of meh trying to apply it using the plastic bag method and getting the bag stuck to the balsa or what ever else I use to apply it. This is new to me so I am going to have to practice on some scrap balsa.

I used to be in the "anti-CA" camp, due to bad experiences like you describe. But I figured out how to work with it, and an uneasy truce became something of a love affair.

Just be careful with ventilation and personal protection. Have some debonder (acetone) handy in case you get your fingers stuck! I often use a qtip to spread CA on fins... try it with some scrap.

warix said:

Ok so CA is super glue. I think I knew that but it has been a while since I heard it called that. I never knew that you could apply it to balsa to make it stronger. Honestly it kinda scares me a little. I have never had good luck with super glue. I get it everywhere when I use it. I am having visions of meh trying to apply it using the plastic bag method and getting the bag stuck to the balsa or what ever else I use to apply it. This is new to me so I am going to have to practice on some scrap balsa.

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This link will show you the different types of CA that are available, www.hobbylinc.com/ca-super-glue

I use this type of applicator, which is jammed onto the tip of the CA bottle, to get the CA where I want it. These applicators will greatly aid in keeping a CA mess to a minimum for beginners and almost no mess after you become familure with its use. www.hobbylinc.com/glue-tips-glue-applicators

I plug up the end of the applicator with a sewing needle when the CA bottle is not being used to keep the CA from being continuously exposed to air. The top 1/8th of an inch of the applicator will adhere to the needle after sitting around. This portion of the applicator will bust off when the needle is pulled out. You can easily get a dozen uses out of a single applicator.

Six applicators for .95 cents. What a deal!

Just scrape the applicator debris off the needle and the needle will be good for reuse.

I haven't tried the plastic bag method, sounds like a mess waiting to happen to me.

I place the applicator tip directly on the wood to dribble CA into the balsa. You can see the CA being absorbed into the wood and see when the maximum absorption point is reached. The tip of the applicator can be used to push around any CA that pools up after the max has been reached.

Sand and fill/fill and sand the wood grain as needed.

This is great info! I am glad I started this thread. I am learning a lot! Thank you.

Since I have already applied primer to the rocket is adding the CA going to help or should I just keep this in mind for my next build?

CA will not penetrate the primer. Do this when you start your next project.

bradycros said:

CA will not penetrate the primer. Do this when you start your next project.

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That's what I thought! Well that gives me a good excuse to buy another kit!

Indeed it is a good excuse to buy another kit. So is "it's rainy outside and I'm bored." or "I was walking by the hobby store, I tripped, hit my head, and the next thing I knew I had a bag with several rockets in it."

You will find this place is filled with people who have very creative ways to rationalize adding to already huge "build piles."

What's better than having a Der Red Max? Having two, of course. Or three. In different colors. Or longer body tubes ("Der Big Red Max" had an 18" body tube). Or 24 mm motor mounts for bigger engines.

Oh warix, your fun has just begun.

Marc

warix said:

Ok so CA is super glue. I think I knew that but it has been a while since I heard it called that. I never knew that you could apply it to balsa to make it stronger. Honestly it kinda scares me a little. I have never had good luck with super glue. I get it everywhere when I use it. I am having visions of meh trying to apply it using the plastic bag method and getting the bag stuck to the balsa or what ever else I use to apply it. This is new to me so I am going to have to practice on some scrap balsa.

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It won't stick to the bag. I wouldn't tell you something that didn't work and anyone here will vouch for the method I'm sure

The bag method works well.

In fact, last night I was correcting a goof on a composite fin (built from two parts of balsa) and actually sandwiched the piece between two layers of bag plastic while the CA dried. Later, peeled off the plastic.

Enjoy

AfterBurners said:

It won't stick to the bag. I wouldn't tell you something that didn't work and anyone here will vouch for the method I'm sure

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Thanks for the confirmation. I didn't mean to sound like I thought you would tell me something that does not work. I just meant to say that I have always stayed away from superglue if I could because if it can be messed up I will find a way to do it.

I am actually excited to try this.

Whenever I uncap a tube of thin CA it almost always goes somewhere I don't want it to go. :blush: I always cover the immediate area with plastic wrap or wax paper. Acetone is always at the ready (nail polish remover works to debond super glue as well). If you're like most of us, you will glue your fingers together at some point. Heed the warnings about ventilation; your eyes and nose will thank you.

AfterBurners said:

It won't stick to the bag. I wouldn't tell you something that didn't work and anyone here will vouch for the method I'm sure

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Marc_G said:

The bag method works well.

In fact, last night I was correcting a goof on a composite fin (built from two parts of balsa) and actually sandwiched the piece between two layers of bag plastic while the CA dried. Later, peeled off the plastic.

Enjoy

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If the method works or not was not the point I wished to make. I was only pointing out the potential for a unwanted mess you'll get stuck (to) with.

Working with CA if you're not careful regardless can be a very sticky situation :lol::lol:

Marc_G said:

The bag method works well.

In fact, last night I was correcting a goof on a composite fin (built from two parts of balsa) and actually sandwiched the piece between two layers of bag plastic while the CA dried. Later, peeled off the plastic.

Enjoy

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I have a question: I know CA won't stick to a plastic sandwich bag. Will it stick to the kind of plastic cheap food service gloves are made of? I was thinking of wearing some of those when I attempt to fill a balsa transition I'm using, but I don't know if the non-stickiness applies to all types of plastic.

lcorinth said:

I have a question: I know CA won't stick to a plastic sandwich bag. Will it stick to the kind of plastic cheap food service gloves are made of? I was thinking of wearing some of those when I attempt to fill a balsa transition I'm using, but I don't know if the non-stickiness applies to all types of plastic.

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It might I never use gloves with CA for that reason. This process should have your fingers out of the way of any CA of course you have to be careful

One of the forums prolific posters, K'Tesh, documented his technique here. Good stuff !

https://www.rocketryforum.com/showt...econes-Look-Like-Plastic&highlight=nose+cones