On Mon, 23 Dec 2019 15:40:17 -0800 (PST), wrote:

On Monday, December 23, 2019 at 6:32:54 PM UTC-5, Jim Wilkins wrote:
wrote in message
...
...Banging out the hollows wasn't hard, but I would have needed more
practice or some instruction to shrink out the edges....
Ed Huntress

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How did you try to shrink the metal?

I used a home-made leather-faced slapper and a dolly. It was the same dolly I used over 50 years ago on steel.

I didn't anneal, but the aluminum was already pretty soft. I have used the old trick with plain acetylene to leave a layer of soot, and then burning it off with the torch. That anneals aluminum very well, but I wasn't getting the buckles out with the method I tried. It's supposed to work.
Making a paper pattern over the buck, cutting the aluminum to the
patern, forming it over the buck allowing overlaps if required, then
trimming and welding to achieve the basic shape makes the job a lot
easier than working from a flat sheet and attempting to do all the
shaping by stretching and shrinking. There is a limit to what you can
do with an english wheel, plannishing hammer, and shrinking dies -
muchless with a paddle and leather bag.

That's how we formed the nose-bowl for the Pegazair project. I
"carved" a form out of pink foam, then we made the patterns, formed
the aluminum with the hammer and bag, welded the panels together, and
wheeled and plannished it to final shape, theun using shtinking dies
put the lip around the edge (simplified version - but basically
correct), We DID have to anneal the material several times, and for
filler tig welding the panels together we used strips sheared off of
the metal we were working. The seams dissapeared completely on the
finished product.