My favorite cone mandrel is an old heavy cast type positioned in my acorn table work area. However, it has a blunt tip and the smallest ring I can form on it has a diameter of about 1.5”. Often, I want to form a tighter radius, so, I made a work-around tool to permit that work.
I made a symmetrical trapezoidal pattern 7.5” across the base, 5.75” tall and 4.5” across the top. I rolled a cone from 10 gauge sheet scrap and MIG welded the seam. Then I hot fitted the hollow form cone sleeve to the tip of the cone mandrel.
Next I forged a piece of 1.25” round to a taper a couple of inches long which closely matched the line of the cone sleeve. That solid tip was welded to the cone sleeve and blended for a smooth transition of the surfaces.
Finally, I welded a large punch drop to the base perimeter to serve as a knock-off flange in case the tool got tightly jammed onto the mandrel.
This tool works really well. It’s simple. Probably, it is not original, but I’ve never seen another. It can be made in less than a half hour from scrap and it has saved me a lot of time and frustration. My nickname is “the witch hat.”
Offered for what ever it is worth.