Randall Young wrote:
>
> > Don Malling wrote:
> > >
> > > How does one "gather the metal"?
>
> Mike Porter replied :
> >
> > ... But, simply, using a hard metal dolly
> > underneath an area and lightly hammering with a soft-head
> > mallet (rawhide is best, rubber less so) creates ripples in the
> > metal which then merge, thickening the metal in that
> > area.
>
> This is far beyond my current skills, but I've also read of heating the area
> with an OA torch and then quenching it with a wet rag. This will supposedly
> shrink the metal, and solve "oil canning" where you have big ripples that
> move around when you try to work them.
Cold shrinking is preferred, since heating the metal causes some distortion. In
the few instances in which I've done it
cold, it's actually a controllable and fairly quick process when the dent is
not large. Can't say about big
panels--certainly would take more time and finesse.
> There are also "shrinking hammers", but it seems most people say they don't
> work very well.
Rawhide is best. The low-cost shrinking hammers described as such often have a
rubber head with a striker plate bonded
to the rubber, with swirls cast into the metal (the advertising suggest these
swirls are doing the gathering). These are
to avoided, because the swirls dent the metal. They do work, but it's the
rubber that's doing the shrinking, not the
swirls in the plate. Once the dent is shrunk out, one has to grind out the
swirls, making the metal thinner, and then it
warps again. Such hammers are a pain in the butt, and usually are about half
the price of a decent rawhide hammer.
Cheers.
--
Michael D. Porter
Roswell, NM
[mailto:mporter@zianet.com]
Never let anyone drive you crazy when you know it's within walking distance.
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