Creating a swaged hole in the bottom of a fuel tank.

Dear All,

I am starting to build my center section fuel tank and need information
about how to swage holes in the bottom of the tank so that I can edge weld
the six fittings specified in the plans. Four of the fittings are finger
strainers and one is for the sight gauge. There is one more hole on the top
for the filler. As there are only six holes in three different diameters, I
was thinking about doing it using simple hand techniques rather than
expensive tooling.

Here is my idea. The tank is .090" 5052. I planned on drilling holes
(.180+flange dimension) undersize in the aluminum. Then centering the holes
over 3/8" steel plate with holes .180 oversize, then use a polyethelene
bossing hammer to swage the edge of the hole into the female die hole. The
holes in the female die would have the edges relieved to accomodate a bend
radius. It might be time consuming but educational.

Any advice or previous experience to share

--
John "Ebby" Ebensperger
Hatz Classic s/n37
Camden, NY