Thursday, August 06, 2009

Foam nose cone fab

While the filler is drying, I thought I'd document how I'm making the nose cone for an unnamed and not yet designed BT-101 model.
  1. I first cut three rings from a sheet of 2" pink foam using hole cutters. The lower 2 were slightly larger than the tube diameter and the top one was smaller. This will result in a 4" dia. x 6" long cone.
  2. When turning larger cones on either a hand drill or press, I prefer to use a piece of brass tubing instead of a wooden dowel. I bought a piece of 1/8" tubing from my friendly local hobby shop. Because brass does not turn so well. I fitted a 1" section of dowel on the end of the tubing. This will allow for a nice pointy tip.
  3. I had a 'surplus' shoulder with a bulkhead already installed so the rod was dry fit through the center of the bulkhead and through the thee foam rings. This ensured alignment as the rings were glued together and the rod was glued in.
  4. I glued the rings together using wood glue. This is the first time I've used wood glue for this purpose and it seemed to work fine.
  5. I twisted the shoulder against the cone to score the base and aid in getting the correct diameter.
  6. Then glued the rod in using quick drying Gorilla Glue. The brass rod hung out the bottom by about an inch and the dowel protruded from the top by about a half inch.
  7. When dry, I did some rough trimming with a small craft hot-wire cutter.
  8. I then turned the cone on my drill press using a combo of files and sand paper. The shape was set by eyeball.
  9. I decided to fill the surface with wood filler. When dry, I'll put the cone back into the press to smooth it out. (I'm wondering if I should have used SuperFil epoxy filler...but too late now.)
  10. The next step is be to apply a thin layer of glass. I'll then fill imperfections with the epoxy filler.
I'll make a separate post with one thought I've had for the overall design of the target rocket.