Does anyone have a solution to slightly warped or twisted fins? Asking for a friend...

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Orien

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Was it the Florida humidity? Maybe too much wood filler? Any way to flatten them back out? I, I mean my friend, put weights on them all night with no effect.
 
Balsa, basswood, plywood?

if one of the first two, you might try spraying them with Windex w/ammonia. It relaxes the lignin in the wood fibers and allows you to bend the wood more easily. Once straight (or a touch more in the other direction to account for any ‘spring back’ allow the fins to dry. You might also try sandwiching them between two flat surfaces and allow them to dry.

Only concern is whether the filler will allow the Windex to penetrate the wood fibers.

Hope you can true them up...
 
Balsa, basswood, plywood?

if one of the first two, you might try spraying them with Windex w/ammonia. It relaxes the lignin in the wood fibers and allows you to bend the wood more easily. Once straight (or a touch more in the other direction to account for any ‘spring back’ allow the fins to dry. You might also try sandwiching them between two flat surfaces and allow them to dry.

Only concern is whether the filler will allow the Windex to penetrate the wood fibers.

Hope you can true them up...
They're 1/8" plywood. Heavily sealed with DAP Plastic Wood filler and CA along leading edge with 1/4" of CA around outer and trailing edges. I'm seriously depressed right now.
 
I straighten 1/8 ply by suspending the wood between two items. Placing a weight on the wood to over bend it. Spray some water lightly on the top side. Use a heat gun to dry it. Repeat as needed.

I've straightened a lot of plywood like this as it's hard, it's a crapshoot, to buy flat wood.

In the summer I've used the sun instead of the heat gun. I believe it works better (a slower process)

Tell your 'friend' good luck!
 
Are the fins glued on the rocket already? If not, this is an easy fix...If they are then...yikes.

What I have done with warped ply is to glass both sides and then put a release like mylar on both sides and then mash them with something very flat while the resin cures. This could be done with fins already installed but it would be challenging to set up and if applicable the fins need to have all paint sanded off before glassing. I've never done this with fins already installed...
 
Assuming it is what I think it is, the wood filler is quite porous and there's only a very thin layer of it there. I would expect the Windex to penetrate just fine.

It might also kind of dissolve the wood filler and remove it, though (i.e. you'll need to wipe it off and re-fill afterwards).

Does Windex help with plywood?
 
Assuming it is what I think it is, the wood filler is quite porous and there's only a very thin layer of it there. I would expect the Windex to penetrate just fine.

It might also kind of dissolve the wood filler and remove it, though (i.e. you'll need to wipe it off and re-fill afterwards).

Does Windex help with plywood?
I can sand most of it off then apply the Windex. Then clamp it to a flat surface real tight. I should use heat after that? I don't have a heat gun, but I have a space heater that will singe your leg hairs. I could put them in front of that...
 
Assuming it is what I think it is, the wood filler is quite porous and there's only a very thin layer of it there. I would expect the Windex to penetrate just fine.

It might also kind of dissolve the wood filler and remove it, though (i.e. you'll need to wipe it off and re-fill afterwards).

Does Windex help with plywood?
It worked! I sanded all the filler off, then sprayed both sides with a little windex. Then I clamped them down as pictured to a granite cutting board and put them in front of a space heater. I checked it after 15 minutes, and it was damn near fixed. So I flipped it over for a little longer and it's perfect!
IMG_0617.JPG
 
Suggestion for future wood fins - glass them with lightweight fiberglass cloth and vacuum seal them on a piece of acrylic. You strengthen, add rigidity and seal the wood all in one step. You need to own a vacuum sealer, but other than that, the process takes about 10 minutes and the next morning you have perfectly sealed and smooth fins.
 
Suggestion for future wood fins - glass them with lightweight fiberglass cloth and vacuum seal them on a piece of acrylic. You strengthen, add rigidity and seal the wood all in one step. You need to own a vacuum sealer, but other than that, the process takes about 10 minutes and the next morning you have perfectly sealed and smooth fins.
Is there any reason I can't coat these in CA and sand it smooth?
 
Is there any reason I can't coat these in CA and sand it smooth?

You can use a whole bunch of adhesives, fillers, bondo, etc. If you can spread it on the wood and it cures or dries, it will probably work to some extent. Water based fillers (like wood filler) will likely warp the wood (as you found out). Epoxies and CA will work, but they are really difficult to sand once they cure. Bondo works great, but it is noxious stuff and has the same issues with sanding dust afterward.

I just find that, once you get the hang of it, the quickest and easiest way to seal, strengthen and smooth out wood fins is to glass them. With just a bit of FG fabric, some release layer and some batting (all pretty cheap), you can glass fins all day with a vacuum sealer and they come out perfect, every time, no need to sand. Or, you can use carbon fiber for superlight extra strength and that cool CF look. I like the method because it works, it is very easy, it is quick and there is little to no sanding. If you vacuum bag, you don't even need to be too precise with the laminating epoxy because it will get absorbed in the batting layer.

John Coker has a great video on this:

At the end of the day, you don't need to do anything to the fins if you don't want to. They will work just fine and paint just fine out of the bag. But, if you want to seal them, add some strength, get them smooth and don't want to spend a day sanding them over and over again, vacuum bag glassing is the way to go.

I use a Nesco VS-12 vacuum sealer that I picked up on walmart.com for a relatively low price.

I even glass all my balsa parts on MPRs and some LPRs.

Here is a photo of my LOC IV "glassed" with CF and all the rockets behind it are glassed with regular FG:

PXL_20201004_134747111.jpg

The tube on the black rocket above was also vacuum sealed with CF:

PXL_20201110_234652940.jpg

PXL_20201111_124607422.jpg

To be fair, you don't even need a vacuum sealer. If you want to give it a go, you can find FG fabric at Home Depot/Lowes in the paint section (it isn't great stuff, but it works) get some laminating epoxy (BSI would call it "finishing epoxy") and practice hand layups on a piece of plywood. All you really need to do it wet out the wood, lay down your FG fabric, brush on more epoxy and squeegee it smooth. It will probably bubble a bit and it won't be at smooth as vacuum bagging, but I did the orange rocket in the photo that way and it looks just as good as the black one.

When you are ready to graduate to some better materials, you can find all the stuff John mentions in his video at the Composite Store: https://www.cstsales.com/

I like them because they will sell you smaller quantities so you don't have to buy a 50 yard roll of FG fabric.

John recommends using Aeropoxy 2032 for layups. I used to use that epoxy, but have since switched to West Systems 105/206 because it cures quicker. I think the Aeropoxy gives you a better end product, but it takes days to fully cure and needs to be warm/hot the whole time. The West Systems stuff cures overnight and can do so at room temperature.
 
I really like how your tubes came out. Is there much sanding afterwards? Do you think the sealer would pull enough vacuum to do big tubes?
 
I really like how your tubes came out. Is there much sanding afterwards? Do you think the sealer would pull enough vacuum to do big tubes?

That photo is of the tube right after I put CF on it. I did have to sand the seam a bit, but it wasn't too bad. A couple minutes with a sanding block with 100 grit. What I didn't show was that I then put a very lightweight (0.3 oz) FG laminate over the CF. That was cosmetic - the CF tissue by itself is extremely strong, but it does have a somewhat rough surface and has a weave - it will absorb quite a bit of primer/paint before getting smooth. The FG tissue layer made it smooth and glassy - no sanding required at all!

Generally, I use CF for strength (and it is super light weight) and FG tissue to give it a glassy look. For wood fins, I am not as concerned with strength, usually, as much as using the glassing technique to give them a super smooth finish that doesn't need to be sanded.

My vacuum sealer can handle up to 11" wide bags and I have fit up to 5" tubes in those bags. After that, I usually hand layup larger tubes. I have a couple projects in the queue that use 7.5" and 8" cardboard or phenolic tubes. Those will all get hand layups with CF and FG.

For big tubes now, I usually use the Soler FG and CF sleeves: https://www.sollercomposites.com/FiberglassSleeves.html. I use those sleeves for both hand layups and in the vacuum sealer. They are pricey compared to just getting a roll of fabric, but they are very easy to work with and make the tube glassing process almost fool proof (you still need to rotate the tube if you do a hand layup so the epoxy doesn't pool on one side - another benefit of vacuum sealing).

I can't speak for other sealers, but the reason I picked up the VS-12 was because it has one of the strongest pumps on the market for it's size and price. The consumer versions of "Foodsaver" are twice the price and half the strength. Foodsaver does make some excellent larger/commercial "pro" versions that have the same pump strength as the VS-12, but they are huge and cost 3 times as much. For under $100, I couldn't find anything on the market that had the kind of power the VS-12 comes with.

It easily handles 5" tubes. I don't think the power is the issue for anything larger than that - it is just that it only has an 11" wide opening, so not sure if a 6" tube or larger would fit (I haven't tried, so don't know). It may be possible to jury rig a larger bag to fit into the smaller opening of the sealer, but I haven't tried that either.

For fins, though, I have yet to build a rocket that has wood fins larger than can fit in an 11" wide bag. Usually, anything that big has fiberglass fins to begin with, so there is usually no need to laminate them.
 
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Thats a lot of CA
Toxicity
The fumes from cyanoacrylate are a vaporized form of the cyanoacrylate monomer that irritate the sensitive mucous membranes of the respiratory tract (i.e., eyes, nose, throat, and lungs). They are immediately polymerized by the moisture in the membranes and become inert. These risks can be minimized by using cyanoacrylate in well-ventilated areas. About 5% of the population can become sensitized to cyanoacrylate fumes after repeated exposure, resulting in flu-like symptoms.[31] Cyanoacrylate may also be a skin irritant, causing an allergic skin reaction. The American Conference of Governmental Industrial Hygienists (ACGIH) assign a threshold limit value exposure limit of 200 parts per billion. On rare occasions, inhalation may trigger asthma. There is no singular measurement of toxicity for all cyanoacrylate adhesives because of the large number of adhesives that contain various cyanoacrylate formulations.
 
Toxicity
The fumes from cyanoacrylate are a vaporized form of the cyanoacrylate monomer that irritate the sensitive mucous membranes of the respiratory tract (i.e., eyes, nose, throat, and lungs). They are immediately polymerized by the moisture in the membranes and become inert. These risks can be minimized by using cyanoacrylate in well-ventilated areas. About 5% of the population can become sensitized to cyanoacrylate fumes after repeated exposure, resulting in flu-like symptoms.[31] Cyanoacrylate may also be a skin irritant, causing an allergic skin reaction. The American Conference of Governmental Industrial Hygienists (ACGIH) assign a threshold limit value exposure limit of 200 parts per billion. On rare occasions, inhalation may trigger asthma. There is no singular measurement of toxicity for all cyanoacrylate adhesives because of the large number of adhesives that contain various cyanoacrylate formulations.
That's why I've mostly switched over to fumeless BSI SuperGold, despite it's higher cost. I can work comfortably with it indoors.

However, given it's cost, I would never use it as sealer for large plywood fins. :oops:
 
For anything outside of water based adhesives/sealers (wood glue and wood filler, for example), most of the materials are toxic and can cause long term sensitivity. Always use proper PPE - gloves and a respirator should be considered mandatory. This is also true for sanding the dried/cured products. Virtually all the dust we produce in rocketry is bad for your lungs. I use this respirator and cartridges all the time when building:

https://www.amazon.com/gp/product/B008MCUULW/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B009POHLRC/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
 
Toxicity
The fumes from cyanoacrylate are a vaporized form of the cyanoacrylate monomer that irritate the sensitive mucous membranes of the respiratory tract (i.e., eyes, nose, throat, and lungs). They are immediately polymerized by the moisture in the membranes and become inert. These risks can be minimized by using cyanoacrylate in well-ventilated areas. About 5% of the population can become sensitized to cyanoacrylate fumes after repeated exposure, resulting in flu-like symptoms.[31] Cyanoacrylate may also be a skin irritant, causing an allergic skin reaction. The American Conference of Governmental Industrial Hygienists (ACGIH) assign a threshold limit value exposure limit of 200 parts per billion. On rare occasions, inhalation may trigger asthma. There is no singular measurement of toxicity for all cyanoacrylate adhesives because of the large number of adhesives that contain various cyanoacrylate formulations.
I just did it outdoors and stayed upwind. Had the fin can supported on the cradle. Never caught a whiff. Used gloves, though. Of course, I live in south Florida and it was 73 degrees last night.
 
Good stuff on FG, mtnmanak. What paints did you use on the orange rocket and the green LOC IV?

Those were regular Rustoleum fluorescent orange and green you can find at Walmart. One thing I learned about those paints is that they are ultra flat. Like ceiling paint. So, the decals didn't stick to them at all. If you use the Rusto fluorescent paints, give it one or two gloss clear coats, then decal, then finish with 3 or more clear coats in whichever finish you want.

The only fluorescent gloss paints I could find were true automotive paints (the kind you mix and shoot with a compressor gun) and I am not setup to do that.

For FG, I have pretty much gone to DupliColor Engine Paint from the automotive store and their Engine Clear Coat. Those paints seems to handle "Mach rash" better for high speed flights:

PXL_20201229_004343757.jpg
 
But there is no substitute for going full wrap from Mark at sticker shock. He is an artist.

PXL_20210206_190826054.jpg
 
Those were regular Rustoleum fluorescent orange and green you can find at Walmart. One thing I learned about those paints is that they are ultra flat. Like ceiling paint. So, the decals didn't stick to them at all. If you use the Rusto fluorescent paints, give it one or two gloss clear coats, then decal, then finish with 3 or more clear coats in whichever finish you want.

The only fluorescent gloss paints I could find were true automotive paints (the kind you mix and shoot with a compressor gun) and I am not setup to do that.

For FG, I have pretty much gone to DupliColor Engine Paint from the automotive store and their Engine Clear Coat. Those paints seems to handle "Mach rash" better for high speed flights:

View attachment 450139

Thanks for the details and info, and super-looking Brightstar!

I'm a fan of fluorescents and am building a set of upscaled Estes Beta (TK-45) rockets and planning to paint them in fluorescent colors. I've had limited success with fluorescent paints to date. I typically start with white automotive primer, then spray (always rattle can for me) on the fluorescent paint over that. I've also found fluoro's to be flat, and have yet to put a clear coat over them. I'll have to try that on my current builds, as I have decal sets for each upscale.

Cheers!
 
Thanks for the details and info, and super-looking Brightstar!

I'm a fan of fluorescents and am building a set of upscaled Estes Beta (TK-45) rockets and planning to paint them in fluorescent colors. I've had limited success with fluorescent paints to date. I typically start with white automotive primer, then spray (always rattle can for me) on the fluorescent paint over that. I've also found fluoro's to be flat, and have yet to put a clear coat over them. I'll have to try that on my current builds, as I have decal sets for each upscale.

Cheers!

Absolutely - I learned the lesson with the orange rocket and then did the clear coat/decal/clear coat procedure with the green LOC IV and it worked perfectly.

Definitely a good call on the white primer. If you ever do start with the gray filler primers (good stuff!), make sure you go over it with a coat of white primer before you apply the fluorescents. The fluorescents do not have a thick coverage and need a white base.
 
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