Loft, Draft, Sheet Metal or Revolve?

OK,

Long story short, how would you draw the result of pulling a ball
bearing through a hole in sheet metal? Basically I have a tank, and I
need a flange in the tank that is 1-3/8" ID (1/16" stainless wall
tank). I want the flange to be ~1/4" so you drill a 7/8" hole in the
tank, and using a larger piece of pipe to pull against you pull a
greased up 1-3/8" ball bearing through it welded to a threaded rod.

The result is a perfect spherical flange to weld a fitting onto. I
would like this to be an automatic thing but I think I may end up
drawing the profile of the flange with a revolve, and glueing that to a
larger hole in the tank.

Any ideas?

BTW, this is a rediculously nifty trick for welding fittings onto
tanks.

- Kuli

 

If your tank is a sheet metal part, how about a forming tool?

If not, or maybe instead, what about a smart part?

WT

 

I would agree with Wayne and definitely use a forming tool.