Best Method of Dent Removal?

IMO.
On no account use compressed air. If you want to use pressure use a liquid...
Del

Compressed air will be absolutely fine until the tank splits and exits the workshop at high velocity, killing anything in its path....

DON'T TRY THIS AT HOME!

If you want to be certain you don't split the metal, I would handle it like all typical automotive body work. Take down to bare metal, apply body filler, (Bondo), sand to smooth and shape and refinish. Even if you were to get that dent to pop out, the paint finish will be compromised and you would have to refinish anyway.

Serendipity... in that I, too, have been trying to figure a way to remove a minor 'in-pression' on the tank of my newish bike in order to offer it for sale. A dent that doesn't justify craftsman's participation (or exploitation) or even removing the tank. I take the response about exploding the tank to be one way of stating, more simply, that positive air pressure from within would not work at any pressure unless a way could be found to confine the air to one location just over the protrusion from within the tank; and even then success in not ensured.

On the other hand, negative pressure (low vacuum application upon the outside of the tank should always work satisfactorily, provided....

Provided that a way could be found to conform a vacuum-dome-seating rim to the tank surface (in 3-d) so that a uniform seal could be effectuated -- not an easy task. For one, it is tank shape which (unlike the broad, essentially planar car fender shape) makes any kind of hand-pull suction cup useless for pulling out a bike tank ding. (It must be vacuum alone doing pulling, not vacuum to gain purchase with arm force to un-ding.)

This requirement introduces the problem of how to form and shape a vacuum cavity of correct shape so that (1) the suction interface devise (the vacuum cavity) will apply suction directly to the dent-affected area and (2) the cavity devise will seal smoothly so that the application of vacuum does pulls out only the dent without distorting any sheet metal outside the dent area. (Depending on dent depth and location, it could actually be the case that un-dented area will be more prone to distort than the dent will be to un-distort ... just the opposite as if positive pressure (finger push) was applied directly to the dent's out-pression was applied from within the tank.

Digressing, I have also tried to conceptualize a fixture/tool (something attainable by modifying an off-the-shelf tool/devise) which could transfer hand or tool applied force to push the dent's inside-the-tank surface -- if reachable by hand only a small push would suffice -- but the complexity of forming such a tool would probably outweigh the cost of bike shop repair and repainting, or even purchase of a new tank. So, in my case, it looks like vacuum is probably the only feasible means of dent removal.

Since no off-the-shelf product seems likely to do the trick -- chime in please if anyone knows or thinks otherwise -- my concept now for fabricating a "tank-dent-pull vacuum containment fixture" would be to use plywood --thin enough to get good conformation -- thick enough to not distort (and so fail to give space for the dent to rebound) under vacuum pressure -- which would be laminated and glued to form a kind of hollow, igloo-like structure which could be positioned over the dent. With a port in this "igloo" to which vacuum could be applied momentarily to pop the dent ... in many cases such as mine, no evidence of a former dent will remain.

The bottom-most ply of my little igloo will be the critical one because it will have to be profile templated and cut so that equal pressure will impinge on tank at each point along its perimeter. (The vacuum must not find and place along the igloo perimeter at which tank's sheet metal is more succeptible to bending that the dent is to flexing outward until "popped." The import of this is that in some cases vacuum pullling will not, by itself at least, be effective.)

Once that first ply with center cut-out is formed, following plies to laminate on top are simpler; needing only to incrementally reduce in cut-out size so as to form the vacuum dome directly above the dent. (The decrementing of cutout size is essential in order that the vacuum retention volume be dome (arch) shaped; simply forming up a cube shaped box will be too prone to having the center of the box roof collapse directly over the dent.)

After curing, a resilient sheet material (such as rubber, in tire tube?) glued to the mounting surface (the material serving both to insulate the tank surface from damage and to (with moistening) ensure a tight seal) should be all else needed (apart from drilling & attaching a port, and obtaining a controllable low vacuum pump) in order to suck out that dent; remember, of course, to cut a center opening in the sheet so that pressure reduction "gets to" the dent and not just to the sealing sheet..

As to reservation about time and labor and expense that might be required...perhaps with some modification (such as to sealing component) a bike dealer or repair shop might be willing to purchase to add to their tools.

FYI to OP writer. Obviously, by mention of craftsman, you recognize that there can be no "best method" as per your post title. It is this truism which is the basis for the livelihood of all craftsmen.

Brevquot error...reading aborted.

Remember, pulling a vacuum on the outside of the tank will give you a whopping 14.7 PSI pressure at sea level on the inside. Is that enough?

Not sure why this was voted off-topic. I think is a not a bad idea (although I admit to having just scanned it).

If you can find another similar motorcycle, sans dent, then it is simple to make a mold from a small section of the good tank. thoroughly reinforce the mold, seal its edges against the tank to be repaired, and apply vacuum. Pop. Done.

This would only work on a limited range of dents in which the tank surface has "oil canned" without creasing.

This also depends on how bad the dents is. If its just a little dink fill it with Bondo and repaint. Once had a friend did body work. Had made something to reach inside tank and force out on the middle of the dent. Then using a body hammer would work the edges of the dent. Here is a link to something like what he used. Oh and please make sure you drain and get all the gas and fumes out before you work on it. We would like you to be around to report back on how you made out!

http://www.google.com/imgres?imgurl=http://studianarek.com/honda/wp-content/uploads/2010/03/dent_repair_tool.jpg&imgrefurl=http://studianarek.com/honda/uncategorized/highslide.html&usg=__8Z7w9TRrYPDR3JD04Q5v4J_rHcM=&h=536&w=800&sz=304&hl=en&start=8&itbs=1&tbnid=273fswkFpQepDM:&tbnh=96&tbnw=143&prev=/images%3Fq%3Dbike%2Btank%2Bdent%2Bremoval%2Btools%26hl%3Den%26client%3Dfirefox-a%26sa%3DG%26rls%3Dorg.mozilla:en-US:official%26gbv%3D2%26tbs%3Disch:1

Welcome to the insanity. It appears that some of keyboard police have been taking a little too many steroids.

This is an open forum and moderation was appropriate in light of those whom may know no better than to try it. I know of many kids; teens that lurk here intrigued by the tech and knowledge available. I don't want to be a party to an avoidable accident and I asked that the comment be removed.

No argument on that point bwire, all I was saying was that perhaps the rulebook needs an addition of a general disclaimer of something to the effect "we reserve the right to delete any post that we deem inappropriate and/or dangerous" and call it a day.

It's already there:

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justifying the dumbing down of this forum in the name of safety for the dim, is much like the continuing erosion of the of the constitution under the pretense of national security

It depends on how big your dent is. If it is as small as the one on my tank you might try what I am planning. I want to try the dry ice trick. My dent looks like it was made by a golf ball (but I suspect a mechanic dropped a wrench on it between when I saw it on the showroom floor and when I picked it up).

http://www.ehow.com/how_4793357_dry-ice-repair-hail-damage.html

Otherwise, google paintless dent repair in your area to see what options you have.

Drew

Try this site. Specifically for hail damage but might be of assistance to you.

If its a large dent remove the tank.

fill with water, spot weld puller thing pull out dent. remove stud flat paint.

tell every one you can pull their dents out until you recover the cost of the welder.

it works by spot welding (hence filling tank with water) ( it saves turning tank into a IED)

then with a puller you pull out the dent, then remove the stud, linish it down finish of with flatting paper bit of filler if req flat again paint. done

http://www.autobodytoolmart.com/magna-spot-entry-plus-stud-welder-kit-jo1050-p-16147.aspx

Now In: Made in USA → Dent Repair Tools → Magna-Spot Entry Plus Stud Welder Kit - JO1050

Use a regulator and no more than 5psi, 3psi maybe enough and augment with a suction device on the exterior though sometimes tapping upon the periphery of the dent will cause it to pop out too, material memory is helpful.

Depends on the size & shape of the dent. If it doesn't have any sharp creases, some methods I've tried that worked;

The hair dryer & volatile spray method, (video is a bit slow loading).

The Dink King dent remover, similar to the stud weld method in an earlier post but uses hot melt glue to attach a stud & a puller to remove the dent. Needs a bit of patience but I've removed several dents with the kit I bought.

For more difficult dents do you have a Dent Magician or similar service locally? Might be worth getting a price before you do anything desperate.

Autozone sells a dent puller that uses a "glue" ...

Kinda like the PopsAdent thing that was all the rage a couple of minutes ago..

Touch dry ice to the center of the dent on a heated tank if the dent is shallow and uncreased. best if done on a very hot day in the summer. heating with a heat gun/hair dryer is a recipe for an explosion. Working with gas tanks is very dangerous! You MUST take precautions to ensure that no vapors are ignited.

Use pressurized water (NEVER AIR! too much stored energy! May kill you or other more innocent bystanders if the tank were to split! think bomb!) to pump it out.

If creased, you'll have to use body filler to smooth it out.

Since this is a gas tank, unless you have steam cleaned it well, the vapors in the tank will still be volatile even if filled with water (some residue will float on the surface of the water and vapors will still be hanging around), I would recommend taking care using a stud welder.

Warning of the danger posed by pressurized air is appropriate and use of a regulator is paramount. I'm of the opinion folks will try something even when warned off if they think it will work and they haven't the money to do otherwise so I present low hurdles with firm restrictions.

Absolutely zero welding/brazing or heat guns are to be employed on used gas tanks under any circumstance without having a permitted (document) hi-pressure hazardous materials washout and even then do not do this on your own at home.

Be that as it may I prefer to fill MC gas tank dents with lead rather than bondo...

Don't even think of trying it by pressurizing the tank...you would have a potential bomb on your hands. Leave it to the professionals. Lou Bindner

Actually, the compressed air method is very good at tranferring a dent from the tank to your head.Just hold your head close to the dent for best effect while inflating to 150 psi.

Oh, yeah, I forgot: please fill out an organ donor card first.

All joking aside,the link using the hair dryer and air duster looks real effective.

Rots o' ruck,rocket man.

Some good recommendations here, and two very bad ideas(air pressure, and welding)

Here is another idea to consider, a pump up weed sprayer. Leave the tank bolted in place if possible. It anchors the tank firmly, without damage. Drain all of the gas, and connect the hose of the pump sprayer to the outlet of the fuel tank. Fill both tanks with water. Now close off the fuel cap, and pump up the sprayer. the same heat-cold techniques from above will work, but take a lot longer because heat will be transfered to the water. This might be a good method combined with the hot glue puller. Good luck.

One thing to consider when thinking of when pressurizing the tank is what will pop out first? Probably not the dent. Instead, you will probably deform the tank so it will never bolt back on where it was supposed to.

We've been guessing all over the place here with some good thoughts, how about uploading a picture of the offending dent and we can target the problem with the best solution.

Drew

Put a decal over it or paint the tank with a non-glossy finish if the dent is significantly reducing fuel capacity replace the tank.

When my son came off his bike it put a couple of big dents in his tank. the method that i used was to get a clutch or brake master cylinder. fill the tank with water and slowly pump it up. If it is newish bike the metal is so thin that only a few pumps will push out the bottom of the tank where it sits over the frame. So you will need to make a jig to hold this in place to stop it from happening.you will not need a lot of pressure for this to happen as the dent we were trying to remove was still there afterwards. We only used about 14psi if i remember.

Use body filler would be the best thing, Talking from experience.

Hope this helps you.