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  #21  
Old 09-27-2007, 01:16 PM
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mojo1986 mojo1986 is offline
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Craig,

Many years ago (I shudder to think how many) I used your technique for finishing my fins with mixed results. I started by simply putting a thin coat of white glue on the fin and then laying on the paper which I had previously cut to shape. I quickly learned to cut it a bit smaller than the balsa fin after having to sand the curve into the leading and trailing edges (a LOT more difficult with the paper and glue there) on the first set I fins I produced this way. Fins made this way often warped slightly, especially when the fins were thin. So I then went to peel and stick paper (Estes PRM-1), also with mixed results. Although this solved the warpage problem, I sometimes got a bit of delamination at the fin edges and 'bubbling' on the fin surfaces. So I was never totally happy with the result, and never perfected the technique further to overcome these problems. Still, I continued to use the method for a while for two reasons..............the balsa grain was completely filled with little effort, and the fins were VERY strong.

Joe
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  #22  
Old 09-27-2007, 05:11 PM
Green Dragon Green Dragon is offline
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fin grain needs to be filled, lol ...

when starting out, of course.. I never sealed balsa, then started to use Aerogloss, usually 1-2 coats to seal the wood, but never filled all the grain - hence my vintage builds looking not as perfect.

when I got into HPR, when spending lots more time ( and DOLLARS ), figured they should look nice ( plus plywood seals easier, lol ) , so started making them real clean ( huge influence here by one of my mentors, thnks RON

now into my nostalgioa phase ( I'm NOT a BAR, never left, just been through different phases ) - I strive to make every one more perfect than the last - meaning perfect sealed fins, sanded fillets... never used to fill spirals, but have to admit, my last 3-4 builds / painted projects got filled spiral grooves - including the CHallenger 2 ( originally a 'no painting required' bird

but, if you prefer raw grain and ' going to loose it anyways' flights - been there, done that ( but send me your unused decal sheets from your naked birds, might have use of those

just my 27 1/2 cents ( inflated for modern composite motor costs )


~ AL
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  #23  
Old 09-27-2007, 06:50 PM
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ScaleNut ScaleNut is offline
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Nowadays I like to fill the grain ( in the eary days I didn't care).
but I never understood using a "sealer" to fill the grain, thats alot of work !

If a person just likes the wood sealed than that sounds likes the way to go.
using a filler like f-n-f gets it done in one application, thats why I like it, lees work , great results. even easier for me is paper laminating, I do that alot now, easy and strong.

I need to conserve what braincells I have left anyway ..

no one way is right or wrong just each person's preference
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  #24  
Old 09-27-2007, 10:03 PM
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I often paper fins using standard copier paper and a very very thin layer of yellow glue. I haven't tried it on very thin balsa yet, but on the thicker stuff I've not seen any warping.
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  #25  
Old 09-27-2007, 11:41 PM
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Quote:
Originally Posted by mojo1986
Craig,

Many years ago (I shudder to think how many) I used your technique for finishing my fins with mixed results. I started by simply putting a thin coat of white glue on the fin and then laying on the paper which I had previously cut to shape.


Water-based glues will do that; especially on thin balsa, like 1/16" sheet. I'm also into RC aircraft, and tried laminating a thin balsa skin to a foam core with white glue. It was a disaster, until I found a better method.

Apply the glue in a thin layer to both the balsa and the paper. Allow to dry completely. Lay the paper onto the balsa, then take a Monokote iron and heat-press the paper onto the balsa. The heat passes through the paper to the glue, melts the glue slightly, then creates an impossible-to-peel lamination as the glue polymerizes. By allowing the glue to cure completely, you don't trap the moisture in the wood, which causes the warping problem.


Quote:
...I quickly learned to cut it a bit smaller than the balsa fin after having to sand the curve into the leading and trailing edges


I don't bother doing this anymore. What I do is cut the label sheet to the same outline, press it down, then apply the thin CA to the edges. The CA wicks down into the balsa and sets up rock-hard. Now is when I take the 220-grit to the edges and round them just enough to remove the roughness of the CA.

Sometimes I don't pre-cut the label. I just take the pre-cut balsa fin, lay it out on a piece of label stock, then trim away the excess. The sanding takes care of any remainder.

Quote:
...So I then went to peel and stick paper (Estes PRM-1), also with mixed results. Although this solved the warpage problem, I sometimes got a bit of delamination at the fin edges and 'bubbling' on the fin surfaces.


One thing to keep in mind is the improvements made in adhesives over the past 35-40 years. The current variety of label stock is far superior to whatever was available in the late '60s and early '70s. Go grab some label stock and try the technique again. If you don't seal the edges, however, the label will peel. Sealing the edges with thin CA does double-duty -- it attaches the label edges down firmly, and hardens the edge of the balsa.

Quote:
Still, I continued to use the method for a while for two reasons..............the balsa grain was completely filled with little effort, and the fins were VERY strong.

Joe


It's a laminate, or composite, structure; very much like 1/16" thick balsa plywood (or MDF board). It's going to be stronger than the balsa by itself, no matter how it's filled.
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Last edited by CPMcGraw : 09-28-2007 at 12:28 AM.
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  #26  
Old 09-28-2007, 07:57 AM
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Solomoriah Solomoriah is offline
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I've been using CA to seal fin edges for a while now, and I have to say that it works great!
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  #27  
Old 09-28-2007, 10:34 AM
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mojo1986 mojo1986 is offline
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OK, guys. Time to give the old paper laminating method a try again. You've got me convinced! Especially because I agree that the adhesives used on paper label stock is much better than it used to be. By the way, the dry glue/iron-on method is ingenious if it works well............can't wait to try that! One question though.............what is this 'CA' stuff that you guys use?

Joe
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  #28  
Old 09-28-2007, 10:49 AM
Ltvscout Ltvscout is offline
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Quote:
Originally Posted by mojo1986
One question though.............what is this 'CA' stuff that you guys use?

Joe

Cyanoacrylate better known as Crazy Glue. Any hobby shop will carry the stuff.
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  #29  
Old 09-28-2007, 10:52 AM
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Quote:
Originally Posted by mojo1986
OK, guys. Time to give the old paper laminating method a try again. You've got me convinced! Especially because I agree that the adhesives used on paper label stock is much better than it used to be. By the way, the dry glue/iron-on method is ingenious if it works well............can't wait to try that! One question though.............what is this 'CA' stuff that you guys use?

Joe


Watery-thin Super Glue. Comes in a Teflon bottle, always hardens in the cap before it hardens where you want it to, smokes when you drop it onto balsa sawdust, turns into a hard foam if you hit it with accelerator...

Frustratingly useful stuff...
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  #30  
Old 09-28-2007, 02:00 PM
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mojo1986 mojo1986 is offline
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CA..............cool, thanks, guys. I've used it many times, just not for rocketry.

Joe
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