Papering 2-part fins

Discussion in 'Techniques' started by ActingLikeAKid, Mar 7, 2016.

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  1. Mar 7, 2016 #1

    ActingLikeAKid

    ActingLikeAKid

    ActingLikeAKid

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    Quick question ... If I'm papering 2-part balsa fins (i.e. fins that are glued together with a butt joint)...

    My gut says to go ahead and glue them together as normal, then sand the joint smooth and paper them. But then I thought: Would it be better to combine papering and assembling the fins? So instead of putting the fins between wax paper when the glue is drying ... why not just set the fin on pre-glued white paper as it's drying, then the joint glue will just help the paper attach?

    Does this make sense?
     
  2. Mar 7, 2016 #2

    neil_w

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    I papered my 2-piece fins on the diamond cutter by assembling the fins first and papering after. Worked fine. I used self-stick label paper, and that was my first papering job.

    I think what you're suggesting could work, but maybe you'd have more stuff to get done all at once which would be harder. The way I did it I could first concentrate on gluing the fins together properly, the worry about the paper afterwards. One task at a time.
     
  3. Mar 7, 2016 #3

    neil_w

    neil_w

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    Now that I wrote that I'm second guessing it. Maybe the glue paper would make assembling the fins easier, not harder. Dunno.
     
  4. Mar 7, 2016 #4

    ActingLikeAKid

    ActingLikeAKid

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    I *think* that if I'm judicious with the amount of glue I put between the pieces, I should be OK... For long and boring reasons, I have a backup set of fins, so if I try one and it fails horribly, I have an extra set. ;)
     
  5. Mar 7, 2016 #5

    McKailas Dad

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    I started making 'extra sets' of fins early in my rocket building days. Not so much to have extras, as it was to use a lighter grade of balsa. I didn't feel the heavier grade wasn't necessary, and even after papering, they were still lighter (and stronger) than the balsa that was supplied in the kits.

    I'm one of the goofy ones that thinks plus or minus a .01 gram is going to make a difference :p
     
  6. Mar 7, 2016 #6

    d11rok

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    ALaK,
    I agree with Neil. It is much easier to glue the 2-piece balsa fins together, let them dry, and then label printer them up. (I did this on my cosmic interceptor) You do get a little seam that is barely recognizable in the middle, and I do wonder if your way would alleviate that seam. That said, I imagine you would have to be VERY judicious in your glue use, as any excess would easily show through
     
  7. Mar 7, 2016 #7

    ep29030

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    I do a lot of paper-reinforced fins in model and mid-power rockets. When I have a two-part fin, I butt glue it, then sand both sides smooth. Then, I pre-cut typing paper(or 110# card stock-my favorite) to match the fin pattern. I usually then put yellow glue on the paper and slap it on the fins, both sides at once to reduce warping. Then sandwich the fin with wax paper and put it in a home-made press to keep the paper tight until the glue sets (I clamp them 24 hours). My press is a sandwich of 1/4 inch dense foam on both sides of the fin/wax paper and a couple of 12x12 inch pieces of 3/4inch plywood, held together with 4 wood clamps. The foam helps to keep the paper stretched over the fin. The setup is simple, but it works.

    After 24 hours, take it apart, trim the overhanging paper with an Exacto blade, then coat the paper with thin CA to harden it. Makes fins stiff, and no woodgrain to remove.
     
  8. Mar 7, 2016 #8

    McKailas Dad

    McKailas Dad

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    Speaking of clamps and presses, I found thick pieces of glass work very well. I use a few of those 'black with orange feet' spring clamps.

    FYI I recycled some glass 'lenses' from some halogen lights, it's quite thick, and works great. I don't even use wax paper, I found they pop off pretty easily, and the fins come out smooth as...glass :D

    ImageUploadedByRocketry Forum1457393525.176370.jpg
     
  9. Mar 8, 2016 #9

    ep29030

    ep29030

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    Yes, smooth hard surfaces work well for clamping; however, a sandwich layer of dense foam will coax the paper to wrap around the fin edges--very handy if you've rounded the leading/trailing fin edges before papering (I do). Even 1/8" dense foam will make a noticeable difference.
     
  10. Mar 8, 2016 #10

    McKailas Dad

    McKailas Dad

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    Hmm, I never thought of it that way, for the rounded edges I mean. Clever idea!
     
  11. Mar 8, 2016 #11

    Cabernut

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    For the 2 or 3 part fins I've papered, I have always glued first, waited until dry, then paper. Otherwise you wouldn't know if the joint separated a bit under pressure.

    FWIW, I once made a set of airfoiled fins that i papered with watered down white glue spread very thin - like in the Apogee video. I used foam rubber sheets to help contour the paper. Turned out really well.
     

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