Its deforming the metal gathering it up causing the side being blasted to shrink.
Planish hit repeatedly hammer on dolley to stretch.
There is also Hammer off dolley and will stretch which your gonna need to learn to use.
Trick is when to use which where. Get above mentioned video he makes others about sheet metal wk as well. Go to metalmeat Forums. Buy Key to Metal bumping and Practice more first get shrinking disk your gonna make scrap so practice first. learn
The metal knows its shape and it wants to go back to that shape.
All you have to do is learn how to help it do that.
Get old hood or fender blow it up blasting and practice fixing it first.
be comfortable when your working get roller chair tool tables that roll, move your work when you can into positions that allow you to work in same position for long periods of time comfortably. its not a fast process, but it is addictive.
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Dennis B.
A&P Mechanic, FCC General radio Telephone Operator Line Maintenance A&P Mechanic and MOC Tech specialist. |
Thanks for all the feedback. I have the Key to Metal bumping. I have read that a couple times. I can do pretty good with normal dents and dings but I don't have any experience with large shallow oil canning spots like these. I am trying to learn how to read what the metal needs.
I worked on the smallest crater tonight. Most of it came back to shape pretty easily, but it left a slightly low spot on one side. I worked that area with the hammer and dolley for quite a while but it never came up. My thinking was that the low spot was probably the area that shrunk the most, so it needs the most work. Am I thinking about this correctly? |
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I would flip panel upside down and Planish metal with a Heal dolley & hammer on Dolley the whole area first before flipping right side up then pushing up fairly hard hammer off dolley to stretch metal to raise it back up. I also would probably over stretch it intentionally blowing it up and then shrink it back down with shrinking disk to smooth.
Just what I would do not saying it will actually work for you in your situation though. I'm just a Hack amateur seriously Last edited by Doright on Thu May 21, 2015 11:28 am, edited 1 time in total.
Dennis B.
A&P Mechanic, FCC General radio Telephone Operator Line Maintenance A&P Mechanic and MOC Tech specialist. |
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Joined: Tue Sep 16, 2008 1:17 pm Location: Pahrump NV. Country: USA |
The metal has been shrunk then you stretched it its easy to over stretch the metal if you over stretch the metal it has no place to go it stays down or pushes up. and now you know why you need the shrinking disk. You could use a Tourch but its really easy to over heat the panel and I think The disk a far better tool for doing it. Its also possible you didnt stretch the the whole area enough and are now over stretching that one low area and metal has no were to go. Also you need to think about whole panel not just one area of the panel. Your trying to fix something that most say cant be fixed remember that don't get greedy wanting perfect. There is another way of looking at or way of thinking about the damage others say blasting heats the metal and its stretching on the side being Blasted which is why metal moves toward the blast nozzle. the metal being blasted is stretching and back side has no where to go and the panel pushes out, In which case shrinking is needed on the side that's blasted. I would have gotten an old fender to damage and then practiced this is no easy repair. This is something many a Pro has said it cant be fixed and they are right. Dennis B.
A&P Mechanic, FCC General radio Telephone Operator Line Maintenance A&P Mechanic and MOC Tech specialist. |
Thanks for all the input. I have a shrinking disc and instruction DVD on the way.
I am sure it will never be perfect or even very good. I am really just trying to learn right now. My plan it still to cut the ribbed section out of this lid and weld it into the other one. Don't get me wrong, I would love for it to work out where I could use this lid but I don't expect that result. I think there will be a lot less filler involved if I weld the ribbed section into the other lid. |
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What I meant above was to get it close but dont get overly greedy with it.
Just get most of its shape back with out oil canning and use your filler Dennis B.
A&P Mechanic, FCC General radio Telephone Operator Line Maintenance A&P Mechanic and MOC Tech specialist. |
I got home from work today to find my Dad experimenting with a propane torch. So I spent some time with him and here is what I was seeing. We were heating from the top side of the trunk lid.
We would heat the low area by circling around the low area. We started from the outside and worked in toward the center. The sunken areas would pop back up where they should be just from the application of heat. After the panel cooled they would sometimes pop back down by themselves. If they didn't pop down on their own, they would pop down with very little pressure. We ended up heating and cooling each low area several times. It seemed to be getting better as we continued. I decided to stop and let it cool completely and check the condition tomorrow. More tomorrow. |
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