Tank Repair

[Guest]

I have a small dent (about the diameter of a golf ball and 1cm deep) on my tank. There are no creases etc... Quite a straightforward dent in my opinion. It's on the back of the tank and right in the middle (just in front of where my crotch rests on the seat...!).

I have seen a lot of people online having success with the hairdryer and compressed air method, has anyone actually tried this? The science behind it is logical and I'm keen to try. I'm not sure if the tank on my 2006 Bandit is single or double walled so I'm unsure on the success that I can expect!

Alternatively...does anyone know of anyone in the Southeast (London/Surrey) that does paintless dent repair on motorbike tanks?

Once again, many thanks to all!

[Joeman]

does a hair dryer really heat the metal enough to make the dent pop out??

[Guest]

The hairdryer heats it just enough to warm it up, it doesn't make it pop out. After it's been heating up you spray on the liquid carbon dioxide (spray upside down from any air cleaner) and it comes out at a very low temperature, the sudden change in temperature then causes the metal to contract and then it pops out...makes perfect sense, I'm just looking for some MBF evidence!

[Guest]

The hairdryer heats it just enough to warm it up, it doesn't make it pop out. After it's been heating up you spray on the liquid carbon dioxide (spray upside down from any air cleaner) and it comes out at a very low temperature, the sudden change in temperature then causes the metal to contract and then it pops out...makes perfect sense, I'm just looking for some MBF evidence!

 

After studying Metalergy, I would say that is absolute crap.

The best way I have found for getting rid of dints, is to fill your tank with water (Petrol is too expensive) then cut a tennis ball in half and put the compressed air through that.

A hair dryer does not come up to any where near the heat needed to ply steel like that.

If it really is as small as you say then you are probably best, getting a steel rod and trying to knock it out from the inside.

I don't think a hair dryer could boil a cup of water let alone mate steel malleable enough to be bent. There is a reason we use Oxy-Acetelyn to got it up to 'cherry red' Roughly 1000 - 1600C before trying to bend it. Not just up near 50.

Slap whoever gave you that idea.

[Joeman]

The hairdryer heats it just enough to warm it up, it doesn't make it pop out. After it's been heating up you spray on the liquid carbon dioxide (spray upside down from any air cleaner) and it comes out at a very low temperature, the sudden change in temperature then causes the metal to contract and then it pops out...makes perfect sense, I'm just looking for some MBF evidence!

 

After studying Metalergy, I would say that is absolute crap.

The best way I have found for getting rid of dints, is to fill your tank with water (Petrol is too expensive) then cut a tennis ball in half and put the compressed air through that.

A hair dryer does not come up to any where near the heat needed to ply steel like that.

If it really is as small as you say then you are probably best, getting a steel rod and trying to knock it out from the inside.

I don't think a hair dryer could boil a cup of water let alone mate steel malleable enough to be bent. There is a reason we use Oxy-Acetelyn to got it up to 'cherry red' Roughly 1000 - 1600C before trying to bend it. Not just up near 50.

Slap whoever gave you that idea.

 

See thats what i thought...

But having seen a couple of videos on YouTube, it seems that its the extreme rapid cooling affect of the liquid CO2 that causes the metel to Pop back into shape...

Personally im very dubious, but happy to be proven wrong

[borgy95]

Try it and lets us know? im curious... Ill be honest sounds like an urban myth to me... but if it works, it works.

[Weebl]

After studying Metalergy, I would say that is absolute crap.

A hair dryer does not come up to any where near the heat needed to ply steel like that.

 

It is nothing to do with heating the metal to make it more malleable, it is to increase the temperature gradient when you cool the specified area and therefore increase the shrinking effect.

To the OP; The Steel used in a fuel tank has no shape memory, so this method will only work with certain dents, it won't work across crease lines and won't work if the metal has been stretched as it dented. It is best in situations where you have had a dent 'pop' the metal the wrong way, and the shrink may (or may not) 'pop' it back the right way. That sounds like what you have so it could well be worth a go as long as you don't have to spend money to but stuff to try it. Paintless Dent Repair is quite cheap these days, and if your tank is single walled will be extremely simple for somebody with PDR skills.

[Guest]

After studying Metalergy, I would say that is absolute crap.

A hair dryer does not come up to any where near the heat needed to ply steel like that.

 

It is nothing to do with heating the metal to make it more malleable, it is to increase the temperature gradient when you cool the specified area and therefore increase the shrinking effect.

 

Try this for me then.

Smack a oven tray over your head so it dints. Put it in the oven on 50C for as long as you like the shoot it with a fire extinguisher.

If it takes the dint out, i'll give you £100k and my left nut.

If it isn't to do with making the metal more malleable, then what is the point in doing it?

Kill mother nature?

Run up the leccy bill?

Make you look like a total tit?

Trust me I have played around with taking dints and bends out of thin and thick plate.

The method that has been described here is known as quenching.

Last time that I used it was on a 100m long hand rail, that had to be fully welded on side before being turned upside down, so the other could be done.

As I am sure that some of you are aware, putting heat (especially welding) on to one side of a pipe and no the other turns it in a rather banana shape, instead of straight. So hence when it was fully welded we took it outside, (luxuary of winter and working on a massive farm) and 4 of us proceeded with the oxy to 'hot spot' it. Meaning a long 6m RSJ was placed under the section, then certain parts where heated then rags covered in ice cold water were immediately wrapped around and kept wet until the pipes cooled enough and kept going until it was straight. Quenching is much like anything else to do with metal work. A very fine art to get it right, very very easy to get it very very wrong.

You might as well piss on your tank if you are going to use a hair dryer.

Quenching is meant for shrinking an area, not trying to reverse it like the case is for most small dints.

Get a long bar, put a bend in the end of it and smack the inside of the tank so it looks better.

Managed to take a massive dint out the side of my brothers car using nothing more than a garden for handle and my boot.

Quick tip:

Most video's on youtube are complete and utter crap. And some will do more damage to your bike/car/self/anything else. Than they were in the first place. But then there are just some that are so full of shit the makes eyes must be totally brown.

[Weebl]

Try this for me then.

Smack a oven tray over your head so it dints. Put it in the oven on 50C for as long as you like the shoot it with a fire extinguisher.

If it takes the dint out, i'll give you £100k and my left nut.

 

 

If you don't know what effect localised heating and cooling can have on metal, then perhaps you did not study metallurgy hard enough.

You certainly have not read what I have written to come up with your pathetic analogy above.

Did you read the bit where I wrote 'won't work if the metal is stretched or creased'?

It will only work on the kind of dent that would 'pop' out if you could get to the inside to push, if you are lucky, the rapid cooling will cause enough local movement to have the same effect.

You are so convinced this could not possibly work you are basically accusing me of being a moron, but worst case, absolutely no further damage is caused. You option of smashing around inside the tank could easily cause further denting, so then the PDR guy has multiple dents, high's and lows to fix with complicated stress raisers to work out which dent is which.

Thanks for the completely irrelevant description of quenching though, massively interesting as it was it clearly has nothing to do with what is being talked about.

[uk190]

if its in the centre of the tank in fromt to f your crotch, could you not just use filler and then cover it with a tank pad?

[Joeman]

Try this for me then.

Smack a oven tray over your head so it dints. Put it in the oven on 50C for as long as you like the shoot it with a fire extinguisher.

If it takes the dint out, i'll give you £100k and my left nut.

 

 

If you don't know what effect localised heating and cooling can have on metal, then perhaps you did not study metallurgy hard enough.

You certainly have not read what I have written to come up with your pathetic analogy above.

Did you read the bit where I wrote 'won't work if the metal is stretched or creased'?

It will only work on the kind of dent that would 'pop' out if you could get to the inside to push, if you are lucky, the rapid cooling will cause enough local movement to have the same effect.

You are so convinced this could not possibly work you are basically accusing me of being a moron, but worst case, absolutely no further damage is caused. You option of smashing around inside the tank could easily cause further denting, so then the PDR guy has multiple dents, high's and lows to fix with complicated stress raisers to work out which dent is which.

Thanks for the completely irrelevant description of quenching though, massively interesting as it was it clearly has nothing to do with what is being talked about.

 

Like Harry Hill says, there's only one way to settle this one....... FIGHT!!!!!!

Seriously though, have you tried this hairdryer/cooling technique?? has it worked for you??

Im sceptical, but then stranger things have happened, so im sat on the fence...

Make a video of you doing it so you can win the 100k bet with spanner head

[Weebl]

Seriously though, have you tried this hairdryer/cooling technique?? has it worked for you??

Im sceptical, but then stranger things have happened, so im sat on the fence...

Make a video of you doing it so you can win the 100k bet with spanner head

 

Not tried it myself on a Bike fuel tank and with a hairdryer, no. But I do understand the physics behind the theory. I am not saying it will definitely work either, just that the localised contraction you can cause could make the metal pop back out.

I can not make a video of an oven tray doing it as he suggested because smacking an oven tray will cause it to crease and twist. This is plastic deformation, not elastic. Heating and shrinking a metal with plastic deformation will not make it pop back into a previously held shape.

Quick 2 minute google found a video of the kind of effect I am talking about. Spannerhead, if this meets your criteria, feel free to keep your left nut, I have no use for it, but if you are still willing to send the cash, I will PM you my address. http://www.youtube.com/watch?v=0oQpks0Z ... re=related

[Joeman]

A dent thats pushed in, that wont pop out by its self, must be under pressure to hold it "popped in". So, for a dent to "pop out", applying liquid CO2 might just be enough to cause the centre of the dent to cool and therefore contract just enough to relieve the pressure ( thats holding the dent in) and allow the dent to pop out. I can see that working in principle

I think the baking tray analogy might be right. ive had them pop in, then pop out before (showering my chips all over the kitchen floor!) and i think this technique (if it works) is more likely to work on larger, almost flat surfaces that are more likely to push in and out... Bike tanks are pretty tough, and very curvy, so i cant see it working on a bike tank, accept maybe in the sides.

[Weebl]

A dent thats pushed in, that wont pop out by its self, must be under pressure to hold it "popped in". So, for a dent to "pop out", applying liquid CO2 might just be enough to cause the centre of the dent to cool and therefore contract just enough to relieve the pressure ( thats holding the dent in) and allow the dent to pop out. I can see that working in principle

I think the baking tray analogy might be right. ive had them pop in, then pop out before (showering my chips all over the kitchen floor!) and i think this technique (if it works) is more likely to work on larger, almost flat surfaces that are more likely to push in and out... Bike tanks are pretty tough, and very curvy, so i cant see it working on a bike tank, accept maybe in the sides.

 

Pretty much spot on mate It would have to be able to be pushed out from the inside, I did clarify that earlier on, but if you have no access then this method has the same effect, that of causing a relative movement in the metal.

It won't work on big thick chunks of skin, the metal will have had to elastically deform to stay in a dent, but a thinner sheet where you have a shallow dent with no big radius change might just work. The OP says a shallow dent so worth a try?

Like I was saying, there are no guarantees, but from his description, i would certainly give it a go for what it costs. (a couple of pence for the hairdryers electricity and an aerosol that a lot of offices and such use)

Use the hairdryer to heat the metal around the dent rather than the middle of the dent where you are going to cool, you are trying to raise the temp gradient between the sprayed metal, and the unsprayed.

[Joeman]

Like I was saying, there are no guarantees, but from his description, i would certainly give it a go for what it costs. (a couple of pence for the hairdryers electricity and an aerosol that a lot of offices and such use)

 

I'd say well worth a try, just for curiosity reasons..

If you have any CO2 spray left, squirt it into a Zip lock plastic bag, seal it up, and throw it... as the liquid turns to gas it expands, the bag inflates, and then POP! it explodes... Hours of fun!

[Colin the Bear]

Don't they do vacuum pullers for pulling out this sort of ding. And may I add that if you're getting a dent in the tank just in front of your crotch, you're enjoying the bike in a totally inappropriate wayhttp://i195.photobucket.com/albums/z28/Colin_the_bear/animated-smileys-matrix-002.gif

[Guest]

Don't they do vacuum pullers for pulling out this sort of ding. And may I add that if you're getting a dent in the tank just in front of your crotch, you're enjoying the bike in a totally inappropriate wayhttp://i195.photobucket.com/albums/z28/Colin_the_bear/animated-smileys-matrix-002.gif

 

Glass suckers do work quite well but only on big dints.

2 cases i've seen.

An old work mate, fell off a ladder whilst strapping his bike on to the roof of his Jeep, and on to the roof of his wifes 206. We got some big glass suckers on the roof and pulled as he was inside the car pushing with his shoulders, almost made it look good.

Whilst getting a kebab when 17 I lent on my mates Punto front LHS wing and dented it leaving 2 perfect arse cheek imprints. We used the glass suckers again to pull them out.

Heating won't work which is why I am betting so much money.

I have dented a tank before, when getting pissed off after thinking i'd got a speeding ticket, did the whole top of a CB125, managed to get that out, by bending some 12mm round bar at work, then sticking it in the tank and levering it out.

[Weebl]

Heating won't work which is why I am betting so much money.

 

 

Hmm, you seem to have a serious problem understanding nobody has written or is even mildly suggesting the heat from a hairdryer will be enough to make a steel fuel tank more malleable.

Perhaps it is because you are too busy writing your Sons of Anarchy fan fiction or telling people about the time you ate a kebab, I don't know but I will break it down for you once more using simple numbers to explain.

If a sheet sheet is at room temperature (lets use the number 15 and call them degrees) and you spray freezing fluid on it in a localised area and it reduces the temperature to -100 then you have a difference of 115 degrees and the equivalent shrinking of that localised area is proportional to that.

If you warm the sheet with a hairdryer to 50 degrees, then spray freezing fluid onto a localised area and it reduces the temperature to -100 then you have a temperature difference of 150 degrees and shrinking in that localised area is again proportional (clue, it will be more) That is known as a temperature gradient.

As you state you are still betting so much money, and I have already posted a link to a video that you seem to have ignored which proves the theory works, do you need my address?

[Guest]

Thanks for everyone's input...I didn't realise it would be such a controversial issue but I think a bit of heated debate (no pun intended) is good.

I'm off on holiday in a couple of days but will most definitely give this a go in August. I'll be sure to film the whole thing and post the video.

Personally, I'm 50/50, but an optimistic 50/50!!!

Watch this space!