Easy technique for acceptable filling of balsa fins

[jetra2]

Hi all,

I just wanted to let you all know of a technique I use on my Super Big Bertha to fill the fins. As those of you who've built the SBB, you know the fins are HUGE. Anyways, I used this technique to fill the fins:

1. Spread Fill n' Finish right out of the tube over the fins
2. Use a knife blade, by itself, to scrape the excess off of the fin
3. Let dry and sand
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   It works quite well. I'll try to post pics of the technique soon.
   
   Jason

 

[flying_silverad]

I bought a couple of painting spatulas in "Micheals" about 2 years ago, mainly for mixing epoxy, but it works great for the method you're suggesting. The curved end makes for great fillet forming as well. Another name for them is Palette knives...

I have 2, a small and a large for all kinds of work. Any like tool would do but I like these because of the flexability



https://www.discountart.com/store/media/DA2023.gif

 

[tnrocketman]

I have been using spreading a thin layer of 20 minute epoxy on balsa fins, then covering the surface with copy paper. Then you squeege across the surface to remove excess, layer with wax paper, and stack books on top. Adds virtually no weight, gives a flat surface for paint, and strengthens at the same time.

 

[EMRR]

Originally posted by tnrocketman
I have been using spreading a thin layer of 20 minute epoxy on balsa fins, then covering the surface with copy paper. Then you squeege across the surface to remove excess, layer with wax paper, and stack books on top. Adds virtually no weight, gives a flat surface for paint, and strengthens at the same time.

This is one of my favorite techniques as well.

Nick

 

[wwattles]

I've basically used the same technique, but with 2 sheets of glass with my box of rattle cans on top. Glass scrapes nice and clean with a razor scraper.

For applications where the smooth finish is all you really want (no strengthening) you can use full-sheet label paper. Worked well for an Estes Guardian that blew a fin on a hard landing in the back seat of my car.

WW

 

[limd21]

For applications where the smooth finish is all you really want (no strengthening) you can use full-sheet label paper. [/B]

IMHO, I think the label paper does add significant strength. I've used that technique a lot and it's definitely noticeable how much more durable those fins are than are plain balsa fins. Of course, the epoxy layup will be better.

 

[Orbital]

I like Fill n' Finish. I also use one of those pink Bondo spreaders. On smaller rockets I just glue paper to the balsa before cutting the fin patterns.