Making Cones?

Dr. Yo · Post by **Dr. Yo** » Tue May 04, 2010 3:14 pm

I need to know how to figure how to set a compass to scribe the
appropriate arcs to create a cone. Shroud-calc seems to have
disappeared from the Internet, and honestly, I was never too
clear on how to use it. This is kind of important, as I need it for
a project I hope to have finished for Wonderfest.

Johnnycrash · Post by **Johnnycrash** » Tue May 04, 2010 3:18 pm

http://www.rocketreviews.com/tool_shroud.shtml

Dr. Yo · Post by **Dr. Yo** » Tue May 04, 2010 5:04 pm

That should do the trick-Thanks, John.

Kylwell · Post by **Kylwell** » Tue May 04, 2010 6:23 pm

How about making scones?

Johnnycrash · Post by **Johnnycrash** » Tue May 04, 2010 6:27 pm

Code: Select all

English Scones Recipe

INGREDIENTS&#58;
# 2 cups sifted all-purpose flour &#40;256gm&#41;
# 1/4 cup &#40;60 gm&#41; white sugar
# 2 ½ tsp &#40;12ml&#41; baking powder
# 1/2 tsp &#40;3ml&#41; baking soda&#41;
# 1/2 tsp salt &#40;3ml&#41;
# 1/4 cup &#40;65 gm&#41; margarine or butter
# 3/4 cup &#40;200 gm&#41; sultana raisins
# 1 cup &#40;250 ml&#41; milk

METHOD&#58;

Preheat oven to 425°F or 220°C.

Grease baking tray with margarine.

Sift the flour, sugar, baking powder, baking soda and salt together.

Cut in the margarine or butter till mixture resembles fine breadcrumbs, then stir in the raisins.

Add the milk and mix to make a smooth dough. &#40;add more milk if necessary to ensure mix is not too dry&#41;

Knead very lightly for ten seconds on a lightly floured surface.

Roll or pat to about 3/4" thick &#40;2 cm&#41; and either cut into individual scones or cut into wedges, leaving intact &#40;pizza style&#41; to make a loaf.

Baking time approximately 12 minutes for individual scones, 15-20 minutes for loaf-style.

Brush tops with melted butter after removing from the oven.

 

Variation&#58;

Cheese Scones&#58; Method as above but omit sugar and add 2/3 cup &#40;70 gm&#41; grated Cheddar cheese, and 1/2 tsp &#40;3ml&#41; dried oregano to the dry mixture before adding the milk.

Top each scone with a little additional cheese before baking.

en'til Zog · Post by **en'til Zog** » Tue May 04, 2010 9:23 pm

What's the frustum of a scone?

Kylwell · Post by **Kylwell** » Tue May 04, 2010 9:25 pm

Half past 2?

Johnnycrash · Post by **Johnnycrash** » Tue May 04, 2010 9:33 pm

en'til Zog wrote:What's the frustum of a scone?

I would need hard data for a specific scone. But, here is a calculator to do the math for any scone you like - http://www.aqua-calc.com/calculate.php? ... cated_cone

rallymodeller · Post by **rallymodeller** » Tue May 04, 2010 9:40 pm

I don't like to touch cones. They cost me two seconds each.

Yes, that's me in my old 280ZX.

Johnnycrash · Post by **Johnnycrash** » Tue May 04, 2010 11:09 pm

rallymodeller wrote:I don't like to touch cones. They cost me two seconds each.

Here, you can GET points for hitting cones instead.

Yes, that's me in my old 280ZX.

It's no 280ZX, more like an early 80s Honda Civic Wagon.

Joseph C. Brown · Post by **Joseph C. Brown** » Wed May 05, 2010 6:19 am

en'til Zog wrote:What's the frustum of a scone?

Bilberry.
http://en.wikipedia.org/wiki/Bilberry

Or Gooseberry, if you prefer.
http://en.wikipedia.org/wiki/Gooseberry

Dr. Yo · Post by **Dr. Yo** » Wed May 05, 2010 9:10 am

Sigh. If only my models got this much attention.

never tried baking scones ( though I used to make a fair biscotti )
so, double-plus thanks, y'all.

tetsujin · Post by **tetsujin** » Wed May 05, 2010 12:37 pm

The math, if you're interested:

The base of the conic section has some circumference "a" (diameter times pi) - as does the top of the conic section (let's call it "b")... And there's the distance "l" of the edge of the cone section, measured top to bottom along the edge...

These measurements correspond to measurements on the arc - the outer arc length, the inner arc length, and the width of the strip.

So how do you determine the inner radius of the strip?

The key is that the length of arcs "a" and "b" are proportional to their distance from the center point of the arc. If "x" is the radius of the outer curve "a", and "y" is the radius of the inner curve "b", then x/a = y/b. Then we also know that x = y + l (the edge length of the conic section is equal to the width of the strip used to form it) - so
(y+l)/a = y/b
y/a + l/a = y/b
y/b - y/a = l/a
(ya - yb)/ab = l/a
(ya - yb) = lb
y(a - b) = lb
y = lb / (a - b)

x is then y + l, or (la / (a - b)).

a, b, and l are all known, so there you go.

Dr. Yo · Post by **Dr. Yo** » Wed May 05, 2010 12:47 pm

I'm no whiz with math, but I can follow the formula, ( I hope ) and
assistance is always appreciated, Tetsujin. Thanks.

ajmadison · Post by **ajmadison** » Thu May 06, 2010 9:25 am

How about Geometry? I can follow geometry. Picture a cross section through the central axis of the cone. Interestingly enough its an isometric triangle. The base of the triangle is the desired diameter of your cone. Adjust the height of the triangle to correspond to the desired height of your cone. The length of either the side of the isometric triangle is the radius for your part. The only thing missing is how much of an arc you'll need to sweep out for your cone.

You can calculate it easily enough, its 3.1415 (five sig. figs should be plenty) * triangle base dimension (or the cone diameter). But because I'm a trial & fit kind of guy, I usually cut my part out way, way long, then adjust until it matches the intended cylinder perfectly.

Not making a cone, but a rocket adapter shroud, or similar frustrum? A frustrum is just a truncated cone. Draw your two triangles, sharing the same angle & top point. The shorter side dimension is the 'negative' or 'cut-out' section of the frustrum, the longer side dimension is to the long arc of the part. The area between the short leg & long leg is your shroud.

Chacal · Post by **Chacal** » Thu May 06, 2010 6:51 pm

The easiest way to make a cone is to take a hypercone and cut a tridimensional slice off of it. Voilá, cone.

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