[TheForge] Another elliptical ring jig idea

[Bruce Freeman]

I'm trying to avoid the need for specialized tools like elliptical
mandrels.

After considering some of the exchanes this morning, I'd like to
propose a "new" tool for making elliptical rings.

Make a jig:  Start with a solid rod (or thick-walled tube), 5- to
10-times as tall as its diameter.  The diameter of the rod defines the
interior minor axis of the ellipse.   A short way down from the top,
drill a largish hole into the rod, and insert another "cross" rod (bolt,
thick-walled pipe, etc.).  This can either be swaged or welded into the
hole, or the hole can be a through-hole and the cross rod can be
inserted loosely through.

Now, forge a ring and round it up over the horn or on a cone mandrel. 
Flatten it laterally, but not so much that you can't get it over the
above jig.  Let one end stop on the cross rod, then hammer the rest to
fit, as if on a cone mandrel.  (Note that the proto-ellipse will be
hanging from the cross-rod and around the rod at an angle from the
horizontal.)  Take it off and flatten against the anvil.  Revese on the
jig and repeat until satisfied with the shape.

You'll need a different jig for each size minor axis.  Using a cone
mandrel would avoid this need.

If you have a cone mandrel with a tong-slot, you can make a device that
slides in the tong slot (like a T-guide on a table saw) to support a
"cross rod" where you want it.  Much more flexible than the above jig. 
Don't know yet whether this extra device is needed.

Bruce
NJ

>>> gladish at cnw.com 11/20/2006 11:26 AM >>>
> The larger lower half would be different than the upper half. An
angled
> cut
> of a cone would give you an egg shape.
>
> Rick

...an egg shape being smaller on one end than the other...
I used to use elliptical mandrels all the time when I did
silversmithing, to
form nice bracelets that fit a variety of different wrist sizes.
I think that if I had more than two large-ish ellipses to make of
steel, I'd
just fab a mandrel rather than bend with forks. Like others have said,
the
cone mandrel is magic for making circles.

Andy G.



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