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| Shrinking Sheet Metal https://www.ausmini.com/forums/viewtopic.php?f=2&t=55710 |
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| Author: | Wombat [ Mon Aug 03, 2009 10:15 am ] |
| Post subject: | Shrinking Sheet Metal |
The Mini door I'm bringing back to health has a section half way between the hinges that has been stretched and gone flat . I can push it out to the curve shape but as soon as the pressure is released it drops back. Question is if I shrink the section using heat/rapid cooling method will it go back to the original curve naturally or will I need to hold it out while cooling? |
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| Author: | Goldbrocade_62 [ Mon Aug 03, 2009 4:08 pm ] |
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Why has it gone flat rust repair or accident damage |
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| Author: | Wombat [ Mon Aug 03, 2009 4:14 pm ] |
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Goldbrocade_62 wrote: Why has it gone flat rust repair or accident damage
Accident damage I'd guess- door appears to have been bent back on its hinges> I have knocked out 95% of the dents around the hinges but there is this bit between them that is "floppy" |
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| Author: | Goldbrocade_62 [ Mon Aug 03, 2009 7:44 pm ] |
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It could still be floppy cause you haven't put enough shape back in panel if you put heat on it the low will sink lower |
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| Author: | crisonic [ Tue Aug 04, 2009 12:13 pm ] |
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David, thats a difficult one. Godbrocade is right -shrinking it will increase the low area - just applying heat will not change the shape - you need to upset the metal by stretching it . Given that the dooskin is fixed to the door frameyou cant really get inside to dress up from underneath. So what ever you do is going to require filler - unless you take the skin off the door I would do the following Use a pry bar between the frame and the door skin to lift lots of tiny spots on the skin . Careful use of heat ( cherry red) then pressure from a point touching the skin will lift the low Depending on how big the low is you may have to do this a number of times . Using the flat of your hand you should be able to feel when the basic shape is there Then use the new dollies you just bought to level it as best you can- mind you there is not much space to get your hand in between the frame and skin!!! Dont forget to water quench each spot - otherwise you will get false readings Its easy to go too far and wind up with the dredded oil can effect - then you have to shrink it!!! Next I would use lead to lead wipe the area. If there is not too much needed then use plastic body filler to finish Panel beaters use a special single sided spot welder to attach a washer to the panel then use a slide hammer to pull the panel out . The hammer blows are just like beating the metal and will stretch it. If you havnt got that then a slide hammer used with a metal tapping screw will do the same but you wind up with lots of little holes and thats not nice |
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| Author: | Wombat [ Tue Aug 04, 2009 2:52 pm ] |
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crisonic wrote: you need to upset the metal by stretching it . Given that the dooskin is fixed to the door frameyou cant really get inside to dress up from underneath.
I can get behind it OK - it's area along the front edge of the door between the hinges and goes about 6" in toward the centre of the door - moves in and out about 1/4" - out it is the right contour - release pressure and it drops back (oil can effect?) I have a slide hammer - but as you say lots of little holes not nice |
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| Author: | Goldbrocade_62 [ Tue Aug 04, 2009 4:10 pm ] |
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What you have to be carefull of is when you hot shrink you can end up chasing it you think 1 or 2 may do but end up puting alot more in I like to use little hot spots big ones pull more make sure panel is cold before next one goes in and lightly dress hot spot to take out stress caused from shrinking |
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| Author: | britishvita [ Tue Aug 04, 2009 5:48 pm ] |
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You could try welding staples or some bent nails to the panel then pull with a slide hammer instead of drilling holes |
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| Author: | Wombat [ Tue Aug 04, 2009 6:52 pm ] |
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britishvita wrote: You could try welding staples or some bent nails to the panel then pull with a slide hammer instead of drilling holes
There is a demo video on Youtube showing the use of an electric arc dent remover - Piston arrangemnet with a single electrode that works like a one sided spot welder You touch the electrode to the centre of the dent and pull 
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| Author: | toymini76 [ Tue Aug 04, 2009 7:03 pm ] |
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Unless you are experienced at lead filling DO NOT attempt it yourself. You will cause more damage than it's worth. Good quality filler these days is just as good and anyone can use it. Good luck and see how you go. If all else fails there is always the option of taking it to your local panel shop and getting them to fix it ready for you to finish off. Phil |
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| Author: | britishvita [ Wed Aug 05, 2009 2:22 pm ] |
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Wombat wrote: There is a demo video on Youtube showing the use of an electric arc dent remover - Piston arrangemnet with a single electrode that works like a one sided spot welder You touch the electrode to the centre of the dent and pull
Those machines are very nice!! I guy in Adelaide also makes them, they're called Eagle Dent Pullers from memory - would make what your doing a piece of cake! |
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| Author: | Wombat [ Wed Aug 05, 2009 5:01 pm ] |
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Well it's done - took nearly all day but very satisfying. Got in behind into the tight spots with a variety of tools , levers and bits of wood and with the help of the BFH - handle first I got all the dents out bar for one around the spot weld near the bottom hinge inner hole. That was due to the heavier hinge mounting bracket inside the door pocket and hard to get at. However the hole is elongated and has some splits radiating out from it and will need welding so I'm hoping to fill the dent with a bit of weld and grind it back. Good days work. 
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| Author: | sgc [ Wed Aug 05, 2009 10:27 pm ] |
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Photos 
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| Author: | Wombat [ Fri Aug 07, 2009 10:28 pm ] |
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Before - you can see the thickness of the bog 
After 
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