0-1 This a very easy metal-finishing method. Start of test panel...lumps from stretching at top of picture simulate body panel damage.
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Click thumbnails for larger pictures.

0-5 Start smoothing the lumps formed by the ballpeen using a hammer and dolly.
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Try spending 5 minutes hammering and dollying in the same general area to get a feel for it. You can always shrink it back down.

14 A few more rounds of smoothing and shrinking with hammer and dolly and shrinking disc.
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I have posted snippets of this work on youtube.com. Search for gullwinginn

15Blending the dent area with the stretched area by repeated raising of low spots, smoothing, and shrinking.
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This demonstration is taken from my DVD: Custom Metal Bodywork.

16This took about 1/2 hour and is almost perfect..another ten minutes of the same would have it perfect. Super easy metal finishing.
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You could easily make a dent and fix it dozens of times in the same spot without hurting the metal with this method.

demo1 Test panel quickly shaped with a mallet and shot bag, covered with ink, lightly filed to highlight uneven surface.
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Please wear a full face shield and hearing protection when using the disc.

demo2 Close up of the surface. This took about 1/2 hour. For this demonstration, I used my lower power 3400 rpm 6.9 amp sander/polisher. My 6000 rpm 15 amp sander/grinder is much faster. Finished off with scotch brite pad.
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All the steps required between these two pictures are posted above.

IMG_0540 Don't remove disc from surface of metal until it stops spinning! Videos from others show this dangerous practice! A great way to get hurt. There is no hurry!
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Use a sander/polisher, or grinder with 1750 rpm to 6000 rpm. Anything more may not be safe. Lower rpm takes longer to shrink.

J.
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I no longer make shrinking discs. Please contact Wray Schelin at wesparts@charter.net for a high quality shrinking disc made by the professional metalshaper who first suggested using a flat disc. There are numerous rip-off copycats out there.

K3This reverse curve is an example of shaping metal with a crowned shrinking disc. The low crown disc allows you to make reverses or repair stretched areas inside valleys.
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The low crowned disc will work on almost any panel. For working in deep valleys, modify a stainless soup pan lid by making a depression for the spindle nut as shown below. A shrinking disc will teach you to use torch shrinking for reverses as well.

m01 Or, you can make your own shrinking disc using 18 gage stainless (best) or cold rolled steel.
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Start with an 8" to 10" blank with a 7/8" hole in the center. I do have some stainless blanks left over from before I stopped production. Contact me at: ghiafab@coastaccess.com if you are interested.

m04My shrinker has stippled jaws. The stock jaws will leave marks that need a little more clean up to prevent cracks from forming.
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Click thumbnails for larger pictures.

m06 Smoothing the wrinkles caused by the shrinker. A hammer and dolly will work...or hammer upside down over a flat surface.
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Spend the time to make the surface smooth, or you will get a false read of the contours.

m08 If there is a gap at the edge of the disc, you need to stretch the edge a little and check the contours again.
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The shiny spots show where I did some on dolly stretching.

m09 One way to form the center depression: set the disc on a 2-1/2" stub of pipe, and hammer the spindle nut down. This takes more than a few hits.
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Center the disc by checking the distance from the edge to the pipe in three places.

m12 Check to make sure that the disc spins within 1/16" or so of true, and shrink or stretch and smooth to correct.
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You just need a little crown in the disc so that it is stiff. You can tuck shrink a disc if you do not have a shrinker. See "other albums..." at the top left. This is not an easy project for a first time metal worker.