challenge: Anyone know how to form a perfect cone that

I'm trying to create a perfect cone (standard cone shape) measuring 6' tall, and approx 3' diameter at the base. I can't shape foam accurately to save my life. I could fiberglass over whatever material. So what material could I use, and how could I shape or form a cone this size from it? Please keep it relatively simple if at all possible.

I thought of getting a hoola-hoop, drilling holes all around it, and rinning dowels from each hole to a central point. I don't think that would work so well. Any ideas, please???

Only thing I can think of is you need to somehow create a giant lathe to turn foam on a center to get your perfect cone. Or else you will need a perfect mandrel for your perfect cone and I can't think of something that would work. Unless there a restaurant or store with a giant gnome on top maybe you can borrow his hat

Make a jig out of wood with the profile that you want and then use a hot wire cutter to shape the foam. 40" wide hot wire cutters are easy to make and since you want a simple cone the jig should be real simple too.

Hopefully this thread helps.

https://rocketryforum.com/showthread.php?t=21370

Bryce

lay out an arc on a (big) piece (or seveal laminated small pieces) of construction paper. 74.216" radius and an arc length of 113.0973". Roll it up edge-to-edge and tape it together. Cut a few different sized discs out of mdf, foamcore, wood, whatever: at least 36", 27", 18", 9". Drill 'em all out with a 1" hole on center. Get a 1"dowel 72" long and glue the disks evenly (The biggest at the bottem then 18" apart if you're using the above dims). sharpen the other end of the down and slide your cone onto your construction. Glass it up, and pull the structure and you're done.

check out upscale rocketry's website under techniques there is one for nose cones and they do a very nice job explaining (with pictures of course) the steps that go into making HUGE nose cones. Here is the link:

https://www.upscalerocketry.com/

Matt

redsox15 said:

check out upscale rocketry's website under techniques there is one for nose cones and they do a very nice job explaining (with pictures of course) the steps that go into making HUGE nose cones. Here is the link:

https://www.upscalerocketry.com/

Matt

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Jay and I will be finishing a small nose cone this weekend. We made the jig and cut the foam block down last week. Just have to route it to size and shape and then glass it.

i am going to use that same method for my next nose cone. I am going to try and make the jig so that it lines up with my lathe then sand it (the nose cone) smooth.

Matt

redsox15 said:

i am going to use that same method for my next nose cone. I am going to try and make the jig so that it lines up with my lathe then sand it (the nose cone) smooth.

Matt

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Since neither of us have a lathe we usually just spin the nose cone using a drill. Put a lag bolt in the mandrel (closet poles or large dowels work good) and chuck that in the drill and start it spinning. :grin:

PhlAsh said:

lay out an arc on a (big) piece (or seveal laminated small pieces) of construction paper. 74.216" radius and an arc length of 113.0973". Roll it up edge-to-edge and tape it together. Cut a few different sized discs out of mdf, foamcore, wood, whatever: at least 36", 27", 18", 9". Drill 'em all out with a 1" hole on center. Get a 1"dowel 72" long and glue the disks evenly (The biggest at the bottem then 18" apart if you're using the above dims). sharpen the other end of the down and slide your cone onto your construction. Glass it up, and pull the structure and you're done.

Click to expand...

interesting idea! doubt i could find big enough paper

Unless you typed it wrong, What does you three foot diameter rocket look like

Sheet metal maybe? Ask your local metal fabrication shop for a quote.

Then keep the paper they give you, it will come in very handy the next time you need to justify a hobby expense.

That is an awfully big cone though....

jeffgeraci said:

I'm trying to create a perfect cone (standard cone shape) measuring 6' tall, and approx 3' diameter at the base. I can't shape foam accurately to save my life. I could fiberglass over whatever material. So what material could I use, and how could I shape or form a cone this size from it? Please keep it relatively simple if at all possible.

I thought of getting a hoola-hoop, drilling holes all around it, and rinning dowels from each hole to a central point. I don't think that would work so well. Any ideas, please???

Click to expand...

To be honest what your talking about is simple sheet metal work. Any decent sheet metal mechanic worth this salt could lay it out for you in about 5 minutes.
to discribe the procedure would take more time then I'l like to type. I'll try to find the layout proceedure diagram I used in a class some years back it might be easier to follow then straight written words anyway. it not all that complicated but will require a pair of decent dividers and yard stick compass. For your 6 foot tall cone your layout culd use a 6'-6" beam & trammel points. I think I kept an OLD copy of this sheet at work I'll try to find and scan it tomorrow.
Hope this helps.

found it Jeff:
With a pair of Dividers and a large beam compass you should be able to lay out your Cone by following the procedure contained on the sheet attached.

Sorry it's so light, but its from a 24year old photo copy.. I overlayed most of the text 7 lines, hope it makes it a little easier to read. Our Sheet metal mechanics generally use soapstone Tremmel points with either a very long pipe or alumimum bar to strike arcs for sheet metal cones up to 18 feet long Takes a good bit of floor space to do the full size layout but they roll up and close to hairline joints as close as the tick marks are allowed the finer the tick (step) marks the closer the cone. Getting material large enough to layout large cones would be the bigger problem i'd think. Perhaps a two or three piece cone would be easier to produce for whatever your trying to build.

Thanks John, thanks guys, I'll give that a shot and see how it turns out. I should have said before, I'm trying to build an "Astro Pop" (see my thread under "odd-rocs") Most of you are too young to remember them I think. Oh God, did I just say that?! I'm 40??!!! When did THAT happen????

eggplant said:

Unless you typed it wrong, What does you three foot diameter rocket look like

Click to expand...

It looks like this: