[TheForge] eliptical rings on a cone mandrel?

[Rick]

You could form half, the turn it around and form the other half.  That 
should work.

|8^)>
Rick Crawford at Rafter Lazy C
  Home of Smoky Forge and Lem the Wonder Mule
   In the middle of Northern Illinois

    http://www.smokyforge.com
     rick at smokyforge.com




----- Original Message ----- 
From: <wmullett at bright.net>
To: "Sponsored by ABANA" <theforge at mailman.qth.net>
Sent: Friday, November 17, 2006 3:23 PM
Subject: Re: [TheForge] eliptical rings on a cone mandrel?


> The ellipse formed by a cone is not symmetrical.
>
>>
>> From: "Bruce Freeman" <FREEMAB at pt.fdah.com>
>> Date: Fri Nov 17, 9:45 AM
>> To: <theforge at mailman.qth.net>
>> Subject: [TheForge] eliptical rings on a cone mandrel?
>>
>> I don't happen to have a cone mandrel, so can't try this myself.  I'm
>> hoping someone can give it a quick try and let the rest of us know how
>> it works:
>>
>> Those of you who suffered through algebra are aware of the "conic
>> sections" - shapes that can be derived mathematically from a cone.  The
>> circle, for example is a horizontal slice through a cone.  Blacksmiths
>> make use of this by using a cone mandrel to make perfectly circular
>> rings.
>>
>> What is not so obvious is that the elipse, the parabola, and the
>> hyperbola are all also conic sections.  If look at a cone from the side,
>> it's a triangle.  (Mathematically, it's two triangles, one upside down
>> atop the other, but we don't have to bother about that.  One "half-cone"
>> will do.)  Draw a horizontal line through this triangle (i.e., of the
>> cone), and, as I said above, you've got a circle on the cone.  Draw
>> vertical line through this triangle and you have a parabolic curve on
>> the cone - interesting, but probably not too useful.  (And the hyperbola
>> is even worse.)
>>
>> But an elipse is also possible.  An elipse arises from an angle between
>> horzontal and vertical.  And they're really cool shapes.
>>
>> So, make a ring.  Round it up on the cone.  Then take it off the cone
>> and hammer it from the side to make it somewhat oblong.  Put it back on
>> the cone and hold it at an angle (say, 30 to 60 degrees from horizontal)
>> and "elipse" it up on the cone.  Got that?
>>
>> If some interested folk could try this out and report back, I'd like to
>> hear about it.
>>
>> (I suspect the trick to make this practical might be to make it
>> narrower than wanted on the anvil, as the thing will tend back to round
>> on the cone.  It also may be necessary to take it off the cone
>> occassionally to flatten the plane of the ring against the anvil.)
>>
>> Bruce
>> NJ