G'day all, I hope mild heat and use of a 90kg pull magnet with steel ball bearings will allow the dent to be sorted.
The problem with magnets is that the strength drops off quickly with distance and is proportional to contact area... You may find that 90kg has dropped to less than a kg through the thickness of a tank and the small contact area of a ball bearing. Has anyone actually pulled a dent out in this way? By all means try, but I'll be suprised if you get anywhere near enough force. You could just fill the worst dents or even do a lead wipe on it, but the latter requires considerable practice.
I've done dents this way previously. The magnet is extremely strong and there would be a lot more force than you think. It's a shame that the Tilleys don't accept a 20mm stainless steel ball. I only have 12mm balls that fit in. I don't just use a single ball I use 4 or 5 at a time. It also matters where the dent is and the angle of the dent. The where matters because it may not allow you to heat the area that needs to be treated because of soldered joints etc. The angle matters because if the dent has been caused by a roundish object pushing in the metal it is much easier to get out than say a dent caused by a pointed object. You need a bit of patience and you need to sum up the where and angle before wasting your time.
Recently, I've seen something called a 'Flatliner' used to pull out dents from car bodywork:- http://www.betaginnovation.com/en/products/body-repair/flatliner/flatliner.html Now, I'm not saying that the system itself could be used to remove dents from tanks, but that the basic underlying principle might be employed i.e. attach a suitably-shaped piece of metal to the dent and use that to pull it out. Perhaps epoxy glue or soldering might be strong enough...
I have heard of this being done myself. I don't know if soft soldering would be strong enough as I haven't actually tried it. If soft soldering isn't strong enough it again gets back to my problem of where the dent is and how effectively I can heat the dent. If it's too close to soldered bits to allow silver soldering then you are back to square one. On the other hand if the soft soldering is strong enough to allow the dent to be pulled out a fair bit, the magnet and steel ball bearings will take care of the finishing job. Again, because of my elbow and shoulder injuries the magnet and ball bearings technique is problematic for me. I bought a magnet that had a protruding thread that I could screw a angle grinder handle onto and secure it quite well. That allows me to grip the magnet to drag it back and forth over the dent. Unless you are in the same shape as Mr Universe, forget trying to drag a magnet with this pulling power rapidly over the dent. It's probably not humanly possible.
Over at CCS there is plenty of discussion about removing dents by soldering a rod/screw or similar to the dent and pulling it back into shape. Sometimes you need to resolder the puller as it may become detached in the process, but the results look fine. Tony
Thanks Tony. The magnet shown may not look much but I can assure you it's powerful. I just tried it by placing a knife under a 35mm/1 1/2" piece of hardwood and the magnet on top. It held the knife no problems.
Good luck with it, Matty. I know that the magnet trick is used by instrument repairers to get dents out of brass. If it really is powerful enough, a whole bunch of different sized ball bearings might be the trick... Tony
That magnet looks a lot like an old airline meal trolley magnet. I have a couple floating around here somewhere and they are Very powerful for thier size.
Hi Tony, I do have different size ball bearings that fit into the founts. It's just a shame the 20mm ones just miss as they are bigger and heavier so make more of an impact on the dent. I've used the magnet trick to successfully remove dents. Until my next operations on my elbows I haven't got the physical ability to try again. This link is where I bought my magnet and it gives information on the magnets. https://magnet.com.au/rare-earth-magnets-neodymium-discs.html
Here is the reflector manipulated back into shape with the use of a leather cricket ball. (Thanks to Genesis for the idea) Cleaned with a product called Gumption. It was a very simple clean.
Well, in the 'beginning', I was going to outright lie to you and say he was my neighbour. I knew that wouldn't work as we both know I made a faux pas and actually meant Gneiss. Sorry about that Gneiss.
No worries, glad it worked... PS. Funny magnet storey: Several years back I was given a large magnet that I was told was used for dredging. I've no idea how true that was, but it had warning labels all over it about pacemakers (I think) and trapping fingers. Anyway I brought it home and for want of a better place to put it stuck it on the side of the fridge, only to realise that it couldn't be slid even with my weight on it! In the end it was still on there when we finally got rid of the fridge...
Hence the handle on mine. If the magnet is stuck on a flat metal surface it's very difficult to move without the extra leverage the handle enables. Believe me, even through the brass fount, the ball bearings are well and truly picked up by the magnet
An other way, I have done it on a petrol tank on my vintage car. Put some air pressure in it, not sure on the solder joints. Then gently tap the dents with a rubber hammer, then they may come out. You have to be carefull not to put too much pressure in it, but enough to do the job. I don't know about small dents with creases though. You may decide to leave them. The best way may be to desolder the tank , then it's a easy job. Cheers Rob
Gniess, now I am picturing a group of about 6 blokes standing around an enormous pile of steel all stuck together with one of them asking, "now what are we going to do"
I can't see how that can be a bad idea even using the magnet trick. It can't hurt I suppose even if the pressure that's in the tank isn't enough to be of much help. I'd never know until I gave it a go. In the words of that coolest of men Fonzi - Correctamundo. Anthony, Yes a magnet that powerful would be more hindrance than help. You need a magnet that is powerful enough to hold a number of ball bearing and those ball bearings won't dislodge when passed at speed over the dent (bulge on the inside of the fount) Too weak a magnet and the bearings dislodge, too powerful a magnet and it's too hard to move the bearings with any speed.
To be honest I think I would rather leave a dent than attempt to desolder a tank base and restore that rolled edge afterwards. I'm sure there are people who can do that but it would be beyond anything I would attempt.
Anthony - I've no idea how it worked in practice, but as I discovered a fridge makes the perfect surface for it to stick to.
Gneiss, I didn't bother to attempt to repair the dent. I'll wait until my elbows have been repaired. I've put it together and it's sitting on a cupboard.
Send it to me, Matty, and I'll have it fixed - I'll send it back to you when your elbows have been repaired. But seriously, I've never heard of elbows needing to be fixed - hips, knees, and my cousin had a new shoulder joint fitted, but elbows, no. Best of luck with them, though...
David, To cut a long sob story as short as I can, I've had major problems with my back including multiple operations. The last back operation I had was just over a year ago. It was a 10 hour operation - yes, 10 hours! I was in a sick and sorry state and needed something to do with my time whilst recovering. Enter lamps. Like you, though my surgeon had heard of my elbow complaints, he said it's quite a rare thing. I have Focal Ulnar Neuropathy bilaterally at the elbows. If you ever bump your funny bone in your elbows you will understand roughly where the nerves are that are affected. The funny bone is where thick nerves arrive down your arm then branch out to where they are from the elbow down. That thick nerve in both elbows are crushed. That in turn causes all sorts of pain from my shoulder to my fingers. It makes the muscles in my arms and hands cramp and makes my digits move involuntarily and so on. Not to mention constant pain - think hitting yourself on the funny bone with a hammer every 5 seconds or so. The surgeon speculates that how the nerves were crushed in the first place was me leaning on my elbows over many years to take weight off my back. Once they are done, I need two hip replacements.
After all those ops Matt, and with all that metal in you, you had better keep away from strong magnets....
Nah, the metal in me is even safe for me to have MRI's. When I first had the metal plates and screws etc put into my neck and I then had to have MRI's I used to lay there waiting for my spine to fly out and get stuck to the machine.
