I know some of you might be wanting a cheap alternative to a pipe centering jig. These cones can cost into the $100's and usually are custom built / milled. This version is very cheap and will not cost more than $5.00. I really waned a bunch for a custom bike frame I was working on.
1. finishing washer
2. 807 size stainless steel piping cone for icing cakes and pastries
3. fender washer to fit inside the piping cone
4. normal washer
6. carriage bolt
Just stack the parts in the order listed setting the bolt at the top of the cone. The only tricky part is to make sure the fender washer is perpendicular to the axis of the cone.
That's it!! Although not the most accurate it will work in a pinch.