Sanding cardboard fins

[darthgriffin]

I picked up an Estes Viking on clearance last month and finally decided to start it. The first instruction steps were as usual: sand the sides of the fins, cut them out, then sand the edges. However this kit didn't come with balsa fins, they're cardboard. I can understand the edges, but if I sand the flat sides won't I ruin the white coating?

[HammerZ2008]

#400-600 you can get away with as long as you don't overdo it. Me I just get a sheet of 1/32" balsa and glue #110 cardstock to it and cut fins from that. That kit is a good base for a good many clones as it turns out. I like to get four or more of those kits and go crazy. You have to love these little rockets.

If you do use the card fins, I recommend soaking the fin edges with thin CA to keep them from delaminating on the first flight. That can be done after they are attached to the body tube. If you don't have CA on hand wood glue is better than nothing. The top side, that the die press pushes the die into will have a slightly raised edge as the card layers are bunched up. Sanding helps level that some, but it thins the top layer alot. Again a coat of glue can stiffen it back up and make it easier to paint.

[powderburner]

I am not so sure Estes really did a thorough job of proof-reading here, or that the cardboard actually needs to be sanded.

If there is any sanding necessary at all it would be on the root edge, to be sure that it is nice and square (not punched at some goofy angle by a machine). Other than that I would not recommend sanding (yes, I guess I am contradicting the manufacturer's instructions).

Hammer's suggestion to reinforce edges with CA is a pretty good one, AS LONG AS YOU ONLY DO THE OUTER EDGES. Don't put CA onto the root edge as this is where you need your white (or yellow...or brown) glue to penetrate the fin material for a good structural joint.

[MarkII]

Don't sand the raw cardboard! I don't know why this was included in the Viking's instructions, but no, it doesn't make any sense. When you get to the point at which you have applied primer to the rocket in preparation for painting it, then yes, you may sand the primer coat on the fins if you wish.

Sanding the edges is a different matter, though. I don't know if the Viking's fins are die-cut or if they are laser-cut, but in either case you will want to smooth out and clean up the edges before you glue the fins onto the rocket. With either cutting method, the process will usually leave little "stumps" on the fin edge where it remained attached to the stock material. In addition, if they were laser-cut they will also have dark brown or black burn marks or soot on the edge all the way around. Both should be gently sanded off. Sand lightly, doing just enough to get rid of those cosmetic flaws.

[HammerZ2008]

Die cut pressed paperboard, like the centering rings. About the raised edges, you can take a dowel or spent casing and roll it out on a hard surface to flaten it out as much as you can.

These are very much the same as the old Centuri Vector V or Akela-1 fin cards. May even be the same tooling for all I know.

I tried to get a low angle shot. Hard to see but trust me as soon as the first coat of primer hits it those edges will swell up.

http://www.oldrocketplans.com/estes/est1949/est1949.htm

I looked up my post-beta instructions and found more than one error in them. If anything check the link for the beta instructions. I didn't look mine over that well at first as I had the other copy to go by.

I for one was taken back that the word "Research" was removed from the decal sheet.