Using body filler.

[wbks]

One of my steel tanks has got a deep dent I need to patch up. I've never really used body filler before, so I'm not sure if you can put body filler over another (dried, sanded) layer of filler? It's impossible to spread this much filler at once without risking air bubbles. Would it adhere properly?

[The Stranger:Me]

One of my steel tanks has got a deep dent I need to patch up. I've never really used body filler before, so I'm not sure if you can put body filler over another (dried, sanded) layer of filler? It's impossible to spread this much filler at once without risking air bubbles. Would it adhere properly?

Why not take some of the dent out?

[NDORFN]

Get some Nutech, I think that's what it's called. It's a 2 part filler with aluminium fibres. Been using it the past couple of days and it's the shit. It'll stick to anything, you can put it on as thick as you like, it's changes consistancy as it dries so you start out with a rough shape and as it hardens you fine tune it until it's like working with clay, and it's easy to sand. I'm pretty sure it's what panel-beaters use. I got it from Repco.

[wbks]

Why not take some of the dent out?

I would but I can't bang it out myself and I'd rather use this old tin of body filler that's getting no use, than pay for someone with the tools to do it. I mean, even if I did push it out, wouldn't you still need to use a bit of filler to cover the creases?

[spookytooth]

I have filled some pretty big holes with bondy in cars,and it has stuck to itself ok.

[wbks]

Get some Nutech, I think that's what it's called. It's a 2 part filler with aluminium fibres. Been using it the past couple of days and it's the shit. It'll stick to anything, you can put it on as thick as you like, it's changes consistancy as it dries so you start out with a rough shape and as it hardens you fine tune it until it's like working with clay, and it's easy to sand. I'm pretty sure it's what panel-beaters use. I got it from Repco.

If you put too much in one place don't you risk air bubbles?

[koba]

If you put too much in one place don't you risk air bubbles?

I think about 4mm is considered about the max for doing it right.
You CAN go much thicker, I've seen a few shockers BUT its best to pull the dent if you can and then use bog to finish it.
A Slide hammer can be useful here but if you do anything involving heat be sure to purge the tank fully!

I find the newtech good for the main bit of filling but I prefer to finish it off with good ol' pink stuff as it is much easier to work. (I don't have power tools.)

Make sure the surface is CLEAN, DRYand keyed well. rough it up with course sandpaper. You don't even want the natural grease of you fingers on the surface so wash it down with some prepsol or the like before you bog it.

EDIT: ahh the question! If I'm doing a bit and get air bubbles I just put a nice thin coat of pink stuff over it to fill the bubbles, its a bit fiddly.

[koba]

Practice lots and you will get good at it.

Just as a random bit of trivia a guy I knew dip stripped his rally car while rebuilding it. The car was a bit of a veteran being a factory car built for a jap hotshot. He worked out it had 25kg of bog in it!!!

[CookMySock]

Usually, big bog jobs look like big bog jobs. Ie, they look like shit. You will have fun anyway.

Steve

[wbks]

Well the dent was previously filled in (it has to be atleast 4 centermeters deep) with filler. Seeing as so many of you are suggesting that I bump the dent out, what is the proper way to purge the tank? I used to have mates that block one end of their two stroke expansion chamber, put pressurised air in the other and heat the dent gently with a blowtorch untill the dent pushes out. That's the only way I could think of doing the dent without proper tools.

[CookMySock]

I used to have mates that block one end of their two stroke expansion chamber, put pressurised air in the other and heat the dent gently with a blowtorch untill the dent pushes out. That's the only way I could think of doing the dent without proper tools.

You used to have them? I can see why. Don't you even think of doing that with a fuel tank - you will blow yourself sky high.

Have a good search on KB and with google before you do anything.

Steve

[wbks]

Well of course I wasn't going to try it right now, but I figure there has to be some way of completely purging a steel fuel tank? I've tried pushing it out with a few spanners and anything else I can fit in and get to the dents with but I don't think it's going to work!

[FROSTY:Me]

WBKS Look dude think this through--worst case senario is???
Reality in this case is the job you do looks like shit and youve gotta strip it back and start again--woopdee doo.
Its already a bog job so the dents a few layers down.
Get stuck in with some 40 grit sandpaper and rip into the old bog so youve got something for the new bog to bit into.
Heres a lil secret for ya. Cut a cardboard profile off of the UNDAMAGED side of the tank.
Now make up some new filler and lay it into the dent.
Your cardboard pofile will give you an idea if you are overthickness with the bog.
Let it go half off and you can shape it to close to the profile with a scaper (looks like a small cheese grater)
have fun dude

[wbks]

Just figured I should ask someone who would know before wasting all the filler! I'll have to wait untill tomorrow, anyway. Nah I took the bog off, it's bare metal all over, now. Might as well try it out and see if I can do it in one go, then...

[NDORFN]

I haven't had any air bubbles at all. It's not the kind of stuff that allows air into it in the first place. I filled a dent about 4cm deep and about 10cm in diameter in one go without any hassles. I doubt you could make air bubbles in this stuff if you tried.