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Old 07-08-2018, 05:28 PM
Charlie Myres Charlie Myres is offline
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Join Date: Jun 2013
Location: Narrogin, Western Australia
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Thoughts from an inexpert.
Imagine looking at the edge of a piece of metal with a small dent (low spot) in it.

With a dolly close to the shape of the panel, under the low pushing upwards; one strikes across the low with a flipper, or slapper. The flipper hits each side of the low and pushes the metal down a little and the mass of the dolly lifts the low upwards a little. This is probably not stretching anything, but it is rearranging the metal.

After a few more slaps the low has been raised, until the original shape has been almost restored. At some point the hollow drum-beat from the slapper on semi-supported metal, changes to a "tink" noise as the metal is directly hit against the dolly. When it "tinks" the metal is being stretched.

If you repeatedly check the profile with the flat-of-your-hand, or any other suitable tool or profile, you will have a very good idea when the metal has been stretched enough. If one persists with this technique using lighter and fewer taps with very smooth tools and files lightly and sands perhaps and polishes, then the metal achieves the smoothness you seek. One can say it is planished.

This of course is very laborious and is what a jeweller will do. Using an English wheel is quicker and takes the hit-and-miss out of the slapping,

Cheers Charlie
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Last edited by Charlie Myres; 07-08-2018 at 05:34 PM.
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