Dent Repair: Fill with silver solder or Ghetto Hydroform?

[Err]

I silver soldering to fill a dent that something I could tackle myself?

edit:

Or should plug one end, fill the tube with water so it come above the dent, freeze it, and see if the ice pushes the dent out?

 

[shovelon]

I would think the dent is on the thinnest part of the tube, and would be subject to overheating and cracking from oxygen embrittlement if you do try it.

The only way to make sure that oxygen is not picked up from the inside of the tube is to purge it with inert gas. You could do that if you find the holes in the frame and run argon or C-o2 throughout that tube. You can find holes in the bottom bracket, seat stay and headtube, as well as breather holes in the chain and brakestays. You could also use balloon helium, but you have to really run a lot of volume and it is pretty expensive. The helium can be gotten easy though.

The flux on the outside is formulated to etch the base metal and keep the oxygen from contaminating the area, so that is ok.

Practice on something first, and see how it goes. I would recommend EasyFlow 56, and the white flux.

 

[Err]

I really didn't think overheating would be a problem at the temperatures needed for silver solder.

 

[Andy R]

If you can keep the temperature below 625 degrees Celsius, probably not.

I suppose it's only very small dents you want to fill - like brake levers make on top tubes ?
You could always use soft solder, of course, presumably it's going to be painted afterwards anyway.

 

[Err]

Haha, yes just like the ones brakes make on top tubes.

It's only really necessary if i can find a cheap powder coater round here (baltimore). Otherwise i'll just use filler.

 

[Grannygrinder]

Chemical metal

Could you use chemical metal. Might have to sand the local area to get a good key but when it goes of its rock hard you can drill it tap it whatever you want.

 

[Err]

Re: Chemical metal

Could you use chemical metal. Might have to sand the local area to get a good key but when it goes of its rock hard you can drill it tap it whatever you want.

Is it conductive enough to work for powdercoat?

 

[Andy R]

I wouldn't think so - even flux residues will affect powdercoat results unless every trace is removed.

 

[Grannygrinder]

Not sure

I know filler isn't as we had some cabinets at work that had some small dents in that got filled,went for powder coating and the filler blew out of the cab. Chemical metal does have metal filins in it but i'm not sure. You could ask the powder coaters?

 

[elite504]

if you;re competent with a torch, go for it. Its how your steel frame was put together. Most tubes will plain ol' braze ok. 753 has to silver solder, and the likes of 4130 and 853 should cool naturally without a forcing breeze. No reason why the inner tube needs to be purged. For full penetration welds in ti etc, defo, but a suface braze on steel, should be fine. Caveats are obviously hyper-exotic heat treated, but generally, SS should be absolutely no prob. .