Procedure for attaching fins?

I'm very new to model rocket building, having built two rockets and currently on my 3rd.

The first rocket was a beginners and the fins were plastic that snapped in place. Easy to do and the fins wouldn't fall off.

The second one had balsa fins that glued on. It took a long time to get them stuck on but I was going slow and being super careful. The fins were just cut out of the balsa sheet and glued on. No sanding or filling at all.

Yesterday on the newest rocket I sanded the fins and sealed them with wood filler, and sanded again. I was careful to leave the glue edge free of filler.

Last night I was trying to glue on all 4 fins and still thought I was taking my time and going slow, but apparently I was going too fast because a couple of the fins kept falling off. The glue wouldn't set enough and turning the rocket and putting pressure on another fin to glue it on would pop one off.

Is there an easier method other than putting on glue, holding the fin to the tube for 15 minutes, and then letting it sit for an hour before moving on to the next fin?

The best way to attach fins - in my opinion - is to use yellow wood glue and the "double glue" method. This is how I do it:

Take a fin and put a bead of glue on the root, smooth it out with a finger so it completely covers the area.

Touch the gluey fin to the body tube to transfer some glue to the body tube. There should be a little glue on the body tube for the entire length of the fin root. Not a whole lot, just enough.

Use a finger to remove the excess glue from the fin so there is just a small film of glue on the fin.

Set it aside and repeat on the other fins. Or if you are just trying it out, don't repeat so you know what to expect.

After waiting about 10 mins, apply another small layer of fresh glue to the root of the fin. This should again be a small film which is just enough to moisten the old glue which has set.

Place the fin on the body tube.

The fresh glue will help "activate" the glue which set up in the early steps.

You need to hold the body tube vertical so gravity does not try to pull it to the side. If the fins extend back past the aft end of the rocket you should set it on the fore end where the nose cone will be.

If you are doing all the fins at one time, you again repeat these steps - fresh glue, attach fin, etc.

You can sight down the tube and gently nudge the fins into alignment.

Let the whole thing dry for a while - hour or so - before applying fillets.

Best of luck!

Ditto krulands post:

(The Double Glue Method) construction for all Wood to paper or wood to wood applications actually creates a bond that is stronger then both materials the Glue is binding.

Adding a tiny same glue fillet after the initial fin gluing has dried adds just a little insurance

Micromeister said:

Ditto krulands post:

(The Double Glue Method) construction for all Wood to paper or wood to wood applications actually creates a bond that is stronger then both materials the Glue is binding.

Adding a tiny same glue fillet after the initial fin gluing has dried adds just a little insurance

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+1 also check out Apogee's website. They have a lot of helpful video on rocket construction.

https://www.apogeerockets.com/Rocketry_Video_tips.asp

Also check out the the Peak of Flight issues

https://www.apogeerockets.com/Peak-of-Flight_index.asp

Lots of excellent information. I'm always viewing the website at least one or twice a week looking for something new.

Hey thanks! I'll definitely use the double glue method next time around, and I'll be checking those videos out as well.

Thanks again!

Mushtang said:

Hey thanks! I'll definitely use the double glue method next time around, and I'll be checking those videos out as well.

Thanks again!

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You may also want to consider a fin attaching jig similar to what I listed below.

https://www.hobbylinc.com/htm/est/est302227.htm

I like to use med CA to attach fins. I'm too impatient to wait for wood glue to dry (probably because I'm using too much).

Have a line drawn on the BT with hash marks marking where the root edge of the fin will contact, apply a bead of CA between the hash marks, place the back corner of the fin on the rear hash, then while sighting down your line ease the fin into the glue bead.

You get a few seconds of play time with the fins, or if you break the initial bond making adjustments it takes a bit longer to re-set and cure.

After all the fins get stuck on the rocket (hopefully only the rocket and not my fingers) I usually follow up with some CA filets.

RocketManDan said:

You may also want to consider a fin attaching jig similar to what I listed below.

https://www.hobbylinc.com/htm/est/est302227.htm

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That dodad is handy.

This dohicky is mighty handy.

www.hobbylinc.com/htm/est/est302231.htm

In my experience, fins falling off after I've held the fin in place for 30 seconds with the double glue method means I'm using too much glue.

With the double glue technique, I will usually take some 320 or 220 grit abrasive paper and rough up the surface of the tube where the fin gets glued. I'm not saying sand the crap out of it, just a light sanding. It may be unnecessary, it's just the way I do it

The light sanding of the tube before first glue film probably makes a stronger bond and definitely results in faster drying of the glue.

I lightly sand the entire body tube before building. I figure it helps the primer to stick better as well as the glue.

I think it`s very important to sand of the shiny "glasine" coating to where the fin roots will be glued ,as this aids in making a better bond to the paper fibers of the BT.

Paul T

You can also puncture the fin on the body tube with small pin holes. This method allows the glue to create tiny rivets when it dries...

Everyone here has some great ideas on how to attached and they are all correct. You just have to find what works best for you and what you are comfortable with.

One other thing. Don't use too much glue! That will cause some issues.

RocketManDan said:

You can also puncture the fin on the body tube with small pin holes. This method allows the glue to create tiny rivets when it dries...

Everyone here has some great ideas on how to attached and they are all correct. You just have to find what works best for you and what you are comfortable with.

One other thing. Don't use too much glue! That will cause some issues.

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Alright, how come you didn't add "ask me how I know that"? What's the story?

+1 to this. with the colder months ahead, it takes longer for white glue to dry in the basement, but wood seems to dry faster and bond stronger. On my last rocket, I took the cut out and slid it up so that the bottoms of the arrows were in alignment with the lines drawn which allowed me to get them on straighter, and spaced apart right.

Bahhhh...who am I kidding ,I use 5 min epoxy .

Like the old broad says.......I put that $%^# on everything !



Paul T