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Author Topic: Dent in Tank best process  (Read 710 times)

Offline irk miller

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Re: Dent in Tank best process
« Reply #10 on: Aug 21, 2017, 09:24:24 »
On that note: you can take a length of rod, put a curve on the end of it (like a "J"), then weld a ball or half sphere on the end of it (a wooden ball works too) and use it to massage the crease out.  Heat with a torch will make it easier to move the metal. 

Offline firebane

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Re: Dent in Tank best process
« Reply #11 on: Aug 21, 2017, 09:50:44 »
A crease that deep is not going to come out well and will require filler. Problem with a crease that deep is it may have stretched the metal and pulling it out may stretch it more.

Offline irk miller

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Re: Dent in Tank best process
« Reply #12 on: Aug 21, 2017, 10:04:33 »
A crease that deep is not going to come out well and will require filler. Problem with a crease that deep is it may have stretched the metal and pulling it out may stretch it more.
Heat helps shrink stretched metal. 

Here's a BMW tank I fixed with no filler:

Before


After (with just a little massaging left)

Offline firebane

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Re: Dent in Tank best process
« Reply #13 on: Aug 21, 2017, 10:18:47 »
That is no where near same. The OP is a very hard line crease compared to a soft dent like yours.

Soft dents usually come out fairly easy.

Offline irk miller

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Re: Dent in Tank best process
« Reply #14 on: Aug 21, 2017, 10:34:15 »
That is no where near same. The OP is a very hard line crease compared to a soft dent like yours.

Soft dents usually come out fairly easy.
It has hard creases at the top (chipped paint should inform you) and it had the exact same crease, but vertical, on the other side.  I've done this a hundred times.  You can disagree if you want, but I've done it enough to know. You have to heat the metal to nearly red hot.


Online jpmobius

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Re: Dent in Tank best process
« Reply #15 on: Aug 21, 2017, 12:03:57 »
That's fairly minor damage.  A skilled man can easily render that invisible in an hour needing no filler.  That said, easily is determined by skill and experience.  If you have less, you might have to take more time and care.  Ideally you would weld pins along the crease and gradually pull the dent out with a slide hammer as already noted.  A pin welder isn't exactly cheap, but you may be able to get somebody at a body shop to do that bit for pretty cheap as it will only take a few minutes.  I would not expect much stretching as more than likely the tank simply distorted very slightly to accommodate the dent, and once pulled back it likely will simply return to its former shape.  After that, a hammer and dolly will dress it out, but you'd have to weld one on to a stick to hold it properly inside the tank - again not something most guys will be able to do easily.  That is the only way I know if you want to keep a steel finish.  However, if you are going to paint, you can simply pull the dent out close and use polyester filler (Bondo) to smooth things out.  There is absolutely no downside to using polyester filler.  If done properly, it will never shrink, crack separate or fall out and is very easy for inexperienced hands to deal with.  Like anything, performance depends on the quality of application.  Lead is bomb proof, but has its own problems, is vastly more difficult to achieve the same results with and you are far more likely to have long term problems from flux contamination than any problems you may get with plastic filler.  I suggest you avoid any form of pressurizing your tank and/or heating it up with a torch.  Both can be used under certain circumstances to good effect but this is not one of them, or at the least is completely unnecessary and can make a great deal of trouble if you don't know what your doing.
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Offline Pinky23

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Re: Dent in Tank best process
« Reply #16 on: Aug 21, 2017, 12:47:56 »
I don't know where you are located but there's guys that travel round in vans all over the uk that can fix dents in cars without marking the paint. We have one local to us (anglesey) called the dent man, I've seen them called dent doctor also. He fixed a dent in my wing on my car and I couldn't tell. He didn't charge much either. Might be a worth a go


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Offline XS750AU

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Re: Dent in Tank best process
« Reply #17 on: Aug 31, 2017, 20:55:34 »
Quote
It has hard creases at the top (chipped paint should inform you) and it had the exact same crease, but vertical, on the other side.  I've done this a hundred times.  You can disagree if you want, but I've done it enough to know. You have to heat the metal to nearly red hot.

Irk - can you give a bit more information on your technique. Do you seal the tank and pressurise it? Or do you seal and just rely on the heat to increase the pressure in the tank?  How do you seal and how much pressure?
“Engineering is the art of being approximately right rather than exactly wrong.”

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Offline irk miller

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Re: Dent in Tank best process
« Reply #18 on: Aug 31, 2017, 21:27:57 »
Irk - can you give a bit more information on your technique. Do you seal the tank and pressurise it? Or do you seal and just rely on the heat to increase the pressure in the tank?  How do you seal and how much pressure?
Heat is to soften the metal.  Then, a bar with a curved end (in the shape of a "J") with a convex cup or ball on the end is fed into the tank to massage the crease out.  If you go too far, the sheet metal that's been overstretched (crown) can be heated with a rosebud tip and then quenched with a wet rag.  It will cause the metal to shrink back.  For small raised bumps, you can heat the spot and quench.  For larger raised bumps, massage the metal around the bump in a circle with a planishing hammer and work your way to the center.  This will shrink the bump and move the metal to the center where it was thinned out. I say that, because you can also do this for creases if they pop out and become raised. 

Offline XS750AU

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Re: Dent in Tank best process
« Reply #19 on: Aug 31, 2017, 21:35:33 »
OK, that makes sense.
“Engineering is the art of being approximately right rather than exactly wrong.”

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