Sealing & Smoothing Balsa Fins
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- Опубликовано: 8 фев 2025
- www.ApogeeRocke... -
If you're working with students and would like a technique to make smooth fins, then this video is for you. Here you'll learn how to take a balsa wood fin and turn it into a work of art by rounding off the leading and trailing edges, sealing it with a water-based wood filler, and then sanding it smooth.
If you pay attention to the techniques shown, the task of smoothing out the fins will go faster and with less effort. This means that hand position and how you hold the sandpaper is a little bit more important because you'll work quicker and with more accuracy.
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This was wonderful insight. At 62 years old, I'm still learning. Let's do the math. Elmer's Wood filler 4oz $4.69. HobbyLite filler 8oz $14.99. I'm sold on Elmer's.
Hi, getting back into the hobby. My kids are having kids and I exposed them to this hobby way back when and now it's coming back! We went to the school a few weeks back and shot some A and B rockets up...everyone excited now so moving ahead so all of us are making a rocket. I bought supplies from your store...GREAT assortment and really like these videos...all around a great time...thanks for being there!!
That man is the Bob Ross of rocketry
I love your videos! I am building a dollhouse and custom furniture and your videos really are helping me!
Thanks. I'm glad our videos are helpful in your hobby. I would have never thought it would carry over.
These are FANTASTIC videos. I’ve learned so much watching these... Thanks for doing them.
Glad to have been able to help.
After you've cut the fins from the balsa sheet store it carefully. You can use it later as a template to make more fins that shape :-)
Great tip, thanks :-)
You might need to make another fin if one got broken. (It happens). OR you might like to use fins of the same size and shape on the rockets you build from scratch. If you build a lot of rocket kits it might be worth writing on the balsa sheet which rocket it is for.
Damn I used mine to make wooden sticks to spread glue to make the rocket. Lol
Great video! Thanks!
Put the fins on a scanner. As long as you keep the scale correct you can print it out as a template anytime you need to replace fins.
Thanks for a "back to basics" video. Always needed
No problem, thanks for watching.
Thank you Tim! and thanks for not thinking you have to have picture perfect production or technique- your just getting it done!
Thanks Cycling Dad. That made me chuckle in a good way. I'm far from picture perfect in product or technique. But if it helps other modelers gain the confidence to try a new technique, I'm really happy. Have a great day; you've really impacted mine with your note.
Thanks for this video. This helped me after 20 years away from the hobby.
Me too! I needed a re-fresher; starting to put together a build!
Would not have known to use the wood putty. Thought about simply sealing my piece(s) with a varnish or polymer. Thank you again for sharing.
Great technique and video Tim. I'll give it a try presently. Thanks!
Helped me out. Not doing a rocket but I am painting balsa wood. Much appreciated.
Thanks for watching. :-)
I did a 'high gloss', sealed, finished, repeat as nauseum (nose cone, fins and body) and sanded to be tapered... the friction was so low that I lost the rocket.. it virtually disappeared in the sky .
it was awesome lol :) I wanna' do it again!
GPS next time tho
Glad it worked for you! That is success.
I've done that too😊
I read a trick from Model Rocket News circa 1969. Sand your fins smooth, coat with talcum powder and rub it in to the grain. Blow off the excess. Apply sanding sealer, allow to dry, and sand it. The guy said usually it will be so smooth you only need one coat of sanding sealer. This was using dope based sealer, SIG still sells it. I’m trying it later this week.
I like to use Sig sanding sealer . It's old school, nostalgic, reminds me of building free flight model airplanes back in the 60's. Yeah, you have to deal with the dope fumes but that's manageable for an adult. For most rockets I just sand the fins quite finely and paint and let it go at that. But for a select few I take the trouble to use the sanding sealer. It's a multi step process and takes a while. Maybe the talcum powder trick can speed it up.
Thanks for this excellent demonstration. Very useful and informative.
Am guilty of painting a rough balsa fin but I really wanted to fly so it had to happen. the rocket still went really high, at least for my standards. It took like 20 minutes to find it lol.
That’s fantastic. I never thought of thinning wood putty. It’s a lot cheaper than sealer. Great tip, thanks!
Cheaper, and from what I've gathered in trying to get sanding sealer from local hobby shops, much more readily available.
I've been away from rocket building for about a decade now. My preference for sanding sealers was always the solvent based sealers, apparently now only SIG makes it and it is very expensive from the distributors plus hazmat shipping fees. I am researching the water based fillers and at about 14:23 you mention the warping. That was the answer I was looking for. I will now have to use this material as I have no other choice. Also, messing with methyl ethyl ketone and its stench has probably caused me brain damage throughout my rocket building years.
I was a NAR member and very active in my teens. 50 years later and now retired, I built my first rocket since JHS. I'm back and gonna build that Saturn 5 I could not afford in 1972
Excellent and very informative video! Thank you very much for sharing your knowledge and experience with us!
You're very welcome. Happy to help out.
great videos, learning a lot about rocketry,thanks
Thanks! Glad to help and thanks for watching
a very clear technical video. thanks.
I have been using a homemade solution for 50 years now. It is especially useful now that Dope based filler is almost possible to buy.
I usecbaby powder. I rub it into the surface of the fins. You can then paint a clear lacquer or varnish over it and sand it smooth with 400 or 800grit wetordry sandpaper. I have mixed baby powder into clear varnish as well. Stir and brush it on, over the prefilled balsa. It takes several hours to dry, but sands nice and smooth
Any warping issues?
Always used white glue thinned with a few drops of water for the sealer. Sand between coats till smooth.
How many coats are required?
I tried this and every fin warped, however i figured out a way to do this. apply the wood filler let dry 2-3 mins then take wax paper and place on bottom and top then place a heavy book over the fins. now they stay true.
Great idea!
Hello Tim. I understand the flight characteristics of shaping the fins. But as you said in this video that you did not sand the fins for photo reasons. Was wondering if you have made a video comparing the flight characteristics of both sanded and and sanded fins in the same rocket? Could be a interesting video.
Good work.
I've used model airplane dope, or I sheathed the balsa under a layer of paper, then used model airplane dope, which helped with the damage that can result from landing. Covering the balsa fins with paper then model airplane dope helps the fins I made with an airfoil profile survive the rigors of landing and flight.
Great idea! I was in the hobby in the early '70s, and had G Harry Stines book. Along the lines of Dope, I used a balsa sanding sealer instead of the glue mixture. My Spock Logic says sanding sealer is lighter
Also used the dope paints, as they were superior. Anyhow, I built an Estes Apogee (?), the one with elliptical fins and a boat-tail cone at the base. The kit can out smooth as glass, with knife-edge fins. The sealer/dope strengthened the balsa.
Stuck a C6-7 and it went so high I never saw it again. The ejection chuff cloud was Barely visible. A shame I lost it, but it was an absolute success.
New hobby for covid lockdown
Enjoyed this! Thanks!
I’m curious if the wood filler also strengthens the fin in addition to making it smooth? I’ve had a few rocket fins chip if they land on a road or other type of hard surface.
Wood filler does not add strength.
Bigger parachute maybe...I have the same issue with a large rocket I have, thing comes down like a rock, hasn't broken yet, but It's just a matter of time.
Thanks for the video
thanks!
Has Elmers discontinued wood filler? I've had a tough time finding it lately after using up the last of my tub working through my build pile recently.
My wife recently got me a tub of it from Amazon.
I do wonder which helps make the fins stronger that Elmer's Wood filler or Sanding Sealer dope which is what I've always ever used??
I saw the paper lamination video. I have never tried that so next rocket I want to try whichever sealer is stronger and then add the paper laminate.
Love your videos, where does one get a t-bar for sanding like you have? I've checked online and at Home Depot but no luck.
You can try your local hobby store. We haven't been able to source one here.
Home Depot appears to have some online options but yes they are a bit tricky to find. The only ones I could find online had to be special ordered or cut down to size. If you find a good place to get them please let us know. The one Tim uses was ordered a long time ago and the source is no longer available.
I'll do that. You wouldn't happen to have dimensions, would you?
The one Tim uses is 2" Wide, 10.875" Long, 0.75" Tall.
In case you are still looking: Great Planes (Hobbico) makes a line of excellent ones in various sizes, as well as one made to round and bevel edges. I use www.greatplanes.com/accys/gpmr6169.php veryh appily.
Can you show how to sand the fin to make an airfoil?
Could you add paper for strength? If so before you apply the sealer ??
If you add paper, you won't need sealer.
If i use the wood putty method could i use masking tape and coat the fins after i attach? Or do i have to before i install?
It is up to you. I like doing it before.
@@apogeerockets thank you... will be easier with the aft fins but forward fins have no tabs so maybe ill do it both ways
Do these techniques apply to plywood fins?
Yes. And it is a lot less work on plywood because the wood grain is tighter.
Is there a way to seal balsa while keeping the grain visible?
Yes. See: www.apogeerockets.com/Peak-of-Flight/Newsletter509
Tim: THANKS for suggesting using wire and corrugated cardboard to handle the fins!
I use ammonia window cleaner to thin out Elmer's Wood Filler.
Why? What is the benefit?
@@apogeerockets It's the solvent used in the product. Also quicker drying time.
@@RocketTCoyote That's interesting. How did you find that out?
@@apogeerockets NAR Member's Guide/Sport Rocketry.
Where did you get that sanding T? I can't find anything like it. Great videos. Adding fins to a pinewood derby car. Might try model rockets this summer.
We sell it here at Apogee: www.apogeerockets.com/Building-Supplies/Tools/Apogee-Sanding-Tee
@@apogeerockets Now I feel silly that I didn't check there first!
@@s-ptownsend8919 Don't worry. We only started selling them a couple of years ago.
Stil helping us from miles away
Is the Elmer's Wood Filler as lightweight as using dope sanding filler? I understand the difference in "toxicity" between water based filler and dope based sanding filler.
good question. experiment and let us know the results.
I am here because I have two tea boxes now and I need to learn how to finish them.Now I know to go in one direction when sanding the edges and the dividers inside. For sealing. This box is unfinished. I have Mod Podge. Is that PVA glue? Can I use this as a sealer?
This is not the stuff for you. Sorry. You might try getting advice from real wood-workers.
@@apogeerockets I am getting into wood workers/crafters now so I have asked two. Will wait for their reply. They both use GESSO. But they have not said what woods to use it on. I just don't want to have another kind of glue here that I will never use up. I am not creative.
What type of paint do you recommend for painting after you have done the sealing and sanding?
I don't recommend paint. I think they are all pretty lousy.
@@apogeerockets so, what do you recommend to finish with for color?
@@foxhound1008 I recommend experimentation with different paints.
Can you still use wood filler after mounting the fins? Saw this video a bit too late
Sure. You don't need anyone's permission to try it out. Go for it!
i tried this but my fins are warping when they are dried i coated both sides at the same time is there something im missing?
What is your opinion on durhams water putty?
Never tried it. Go for it.
Doesn't the filler strengthen the fins, too?
Not really anything significant
I have been flying model rockets since 1983 and I was using the wrong material to seal my wood
I'm always thinking there is something better out there too. And when I find it, I'll say the exact same thing. There is no embarrassment in admitting that.
Van Milligan is spelled incorrectly, it is Van Milligen, a placename in The Netherlands.
Like a lot of immigrants to the United States, my ancestors changed the spelling of their surname. I don't know why they did it, as it was a long time ago. But I did see the change in the family tree I have. I visited the Netherlands a few years ago, but I couldn't find the place Van Milligen.
@@apogeerockets Actually it is called "Milligen". The city has gone through a name-change and is called "Nieuw-Milligen". The Dutch Air Operations Control Station is located there. So a lot of aviation is going on there (your ancesters better stayed there :-) ). I am sure you know the meaning of the Dutch word "van"...
all this time ive used automotive filler this is a far better economical idea
what is the deal with sanding in circles you should be only sanding with the grain of the wood always
the grain is FILLED now so no need to sand with the grain
I did this and my fins warped. How do I correct the fins?
There are many great RUclips videos on fixing warped wood. Here is one that I found to be helpful: ruclips.net/video/5Z-qyyWAmiM/видео.html
Using a belt sander: ruclips.net/video/KYpzj5shV4Q/видео.html