straightening metal plate

For the aluminum radiator tanks I'm making, the bases are frames cut
from 1/4-inch thick 5052 aluminum. They are about 23 inches long about
4.5 inches wide, with a cutout about 7/8" inside that.
The problem with both pieces is that the metal is curved slightly, so
that on a flat surface two opposite corners sit about 1/32" off the
I have read about peening the bowed-inward side, but the problem is that
the bowed-outward side needs to form a watertight seal, so I don't want
it marred up. I have some smooth pieces of steel around, but I'm
wondering if doing this on them will still mess up the surface of the
Without special equipment is there any other way worth considering to do
this? I have a 3-ton arbor press and a 20-ton H-frame hydro press, dunno
if they will be of any use or not.
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DougC fired this volley in news:TtGVq.4573 $ snipped-for-privacy@newsfe01.iad:
I assume you're going to TIG weld this assembly. If that's the case, then why not consider clamping and jigging as a way to "straighten" it. Just pull it into line before welding with clamps. That way, the surface isn't marred, and it will stay put after welding.
You're not talking about a lot of twist.
Reply to
Lloyd E. Sponenburgh
I don't have an answer, just an idea from an observation. Certain instruments, clocks etc that have metal plates in them are often seen with a regular pattern of small indentations. As far as I've been able to find out, these are the result of a process that makes the plates flat. I've been meaning to do an experiment: - Get several hardened pins - masonary nails might do. - Mount them all in a drilled steel plate that holds them parallel and packed close together. - Rig up a with a thick plate on top, attach to a press ram and try flattening a bent plate. A big press might be needed.
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Doug - in the mid 1800's clock makers would punch brass gears from heavy sheet, put them in a drop hammer to "straighten" them and then make a final finish cut on the gears. Maybe your 20 ton press would serve as a drop hammer?
DougC wrote:
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The book I read on flattening sawmill circular saws indicated that the way it was done was to stretch the metal on the concave side. My experience with hammer work shows that if you want a good surface after hammering, you've got to start with a polished hammer head and anvil surface. So you'd mark the line you want to follow with the hammer blows, concave side up, then work both sides of that line with a lightly-crowned light hammer, polished face, of course. This is kind of body and fender shop stuff. If the edges need to be good, stay away from them.
Reply to
Stanley Schaefer

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