William Wixon wrote:

years ago i saw a website where a guy was making two stroke engine expansion
chambers by cutting out the shape in two sheets of sheet metal welding them
together at the edges and and inflating them using a pressure washer. it
seemed like a whole lot easier than working the sheet metal on a planishing
hammer. the parts came out SURPRISINGLY round and well formed.
surprisingly few wrinkles, etc. i couldn't find that webpage but here's a
guy doing the same thing on youtube....

http://www.youtube.com/watch?v=I_Z3AIFSd60

there are other "hydroform" videos at youtube.

b.w.



Hydroforming. Works VERY well as long as you pay attention to the welds
and get the cuts correct. I use it with gas welded aluminum and TIG'd
steel. The hard part is visualizing the part when drawing that shape on
the template. You have to allow for the three dimensional forms on the
template.

--
Steve W.