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Make A Custom Nosecone

This article describes how I made a custom nose cone from green floral foam and fiberglass. The example shown here was 5in diameter, 7 1/8in tall with 5/8in shoulder.

Begin with green foam blocks of the sort that some people use to make floral arrangements. This foam can be found at most hobby shops and other stores, and comes in a variety of sizes. Glue together a foam block of sufficient size, if necessary, using a very liberal layer of yellow glue.

Next, you need a hole-drilling bit. I have one that drills holes of 2-inch diameter. The bit looks like an inverted cup with saw-toothed rim, about an inch tall and two inches wide. Drill in to the foam, in the approximate center, to the depth of the bit, and withdraw. Use a hobby knife to remove the isolated foam material, forming a cylindrical hole in the block. The first photo shows the foam block after this step.

Next, carefully wrap your bit in masking tape. and then epoxy it into the hole. Now you can mount the entire block in your power drill. Carefully clamp the drill in a vise, so that the axis of rotation is as vertical as possible. Use a C-clamp or other means to keep the drill trigger in the ON position; use the plug for on/off.

Using a file (and maybe a knife or saw), coarsly shape the block. Do not venture too close to the desired final pattern, but try to make a shape that is nearly round.

CAUTION: The next step is extremely messy and probably not too healthy! Goggles are absolutely necessary, and a breathing mask helps. Cover or remove anything precious within at least 15 feet of the work area. When I finished the turning, I was covered in a half-inch layer of fluffy green foam residue (including my eyeballs, my ear canals, nostrils, etc) and my kids called me the "green snowman". There are still drifts of the stuff in corners of my garage after vacuuming!

Pic 2Start the drill spinning. Use 150-grit sandpaper to shape the nose cone as it spins. Work freehand. Start with a sanding block and switch to just fingers after the foam is rounded. Use a light touch because it is very easy to remove too much material. It is very handy to have calipers to gauge the correct diameter, especially at the base and for the shoulder. Remove a little bit extra from the shoulder, because you need room for a layer of paper/phenolic tubing there.

Finish all the shaping in one session without removing the block from the drill. If you remove it, you run the risk that it will be off kilter slightly when you remount it. Powering on/off is okay.

Congratulations, you have completed the first part of the project! See the photo of my nose cone next to the body tube. In this photo you can also see how the drill bit was installed. You can remove the drill bit at any point hereafter, but I found it useful to retain it until the last possible minute because it makes a convenient handle and mounting point.

Next, we need to harden the nose cone. I'm not sure if this first step is necessary, but I began by painting the entire surface with epoxy and letting it cure. This gave me a firmer surface to work with. Next, lay down two layers of 6oz fiberglass, curing between layers. It can be very difficult to get the fiberglass to lay smooth over such a curved surface. I used four leaves shaped like the template shown here. (This template is only to give the idea; the actual shape will depend on your nose cone.) For the second layer, I staggered the leaves by 45 degrees. A few small patches at the very nose tip can help smooth the top.

Next we construct the shoulder. Use a scrap ring of body tubing and cut out a sliver so the ring slips gently inside the body tube when rejoined. Once the ring is re-sized appropriately, it should be epoxied directly to the foam shoulder.

Now it is time for the tedious smoothing process. Mask off the shoulder. Use wood filler, putty, Kilz, or your favorite filler to fill the surface of the nose cone until you are satisfied with the finish. I find that painting the surface with gray primer helps identify small blemishes that need further work.

The next step is to add nose weight (if you need any). Using the drill, a knife, or sandpaper on a stick, fashion a crude hole all the way up inside the nose cone until you expose the underside of the nose tip. Make sure you have exposed the fiberglass there so you won't be gluing to foam! Drop in the weights and epoxy permanently.

Pic 3Now we cap the nose base. Cut a plywood disk that will match the *inside* diameter of the shoulder ring. Affix an eye bolt or other shock cord attachment device to the disk. Now remove about 3/8 inch layer of green foam across the whole surface of the nose cone bottom. When you are finished, the disk should fit snugly inside, laying flat against the foam. The surface of the disk should be recessed about 1/8 inch inside the nose cone shoulder ring. Glue the disk in position, then make a strong epoxy fillet around the recessed lip where the disk meets the interior of the shoulder ring. The next photo shows the result.

Pic 4It was at this point that I accidentally dropped the nose cone onto the tiled kitchen floor. I can report that there was no damage to either the cone or the floor.

Finally, paint the cone. I chose a Krylon blue with Walmart clear over the top.

I cannot tell you that this job was fast or easy. But it was an incredible learning experience and you will feel a real sense of accomplishment when you have finished. The methods can be adapted to make some very unusually shapes. I'm sure that people will ask where you "bought" such an incredible nose cone.

Contributed by Geof Givens

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