Dent Repair: Fill with silver solder or Ghetto Hydroform?

[Err]

I am not competent with a torch, just an armchair expert crossed with have a go hero.

How bout plugging one end of the tube filling up to the dent with water and freezing it? I know if i plugged both ends i'd risk slitting the tube or a weld, but i think if sealed at only one end the risk would be lowered, and i could freeze it locally with plumbers freeze spray.

 

[shovelon]

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. .

I agree, SS should be no problem. As u say most tubesets are brazed without purge, but on the heavy butted ends where the lugs are and flux can be applied prior to assembly.

 

[elite504]

I agree, SS should be no problem. As u say most tubesets are brazed without purge, but on the heavy butted ends where the lugs are and flux can be applied prior to assembly.

Tiz true indeed. . . but rear brake bridges, canti bosses, cage bosses etc all go on, brased away from the but. And we're talking lower temp SS, sweated on to fill, not a heavily diffused fillett. However, teh caveat now is a have a go hero! Probebly not a home job then. . .
Creative idea with the water. Likelyhood is you'll just blow your plugs out, or as you say split where you don't want it (its hard to control).
My now advice would be to treat it as a car ol old motorcycle petrol tank or the like: Rub down to spray, key in some car body filler, and spray over that. millions or car esorers can't be wrong. .

 

[dyna-ti]

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.

Chemical metal will not stick,it may look a firm bond but is isnt ,there are too many stresses upon it and the cured 'metal' is very brittle
CM is good for patching a car, not for a tube that flex's
Maybe a 2 pac cataloy
A hole is easier to fill as you create an anchor on the reverse side that prevents it from working loose,dents are a nightmare ,this is why popping them out is the preferred method,this is near impossible on closed end tubing as found on a bike frame
Hope some of this helps you decide,sorry to present you with a nightmare scenario



STICKERS

 

[Err]

I've been thinking about the water plan a bit.

Ice expands 9.8% over the water volume. As long as i kept the total volume of water below 91% of the tube volume i don't think i risk blowing out the welds or splitting the tube.

So i reckon if i only plug one end, and half fill the tube, with the tube running vertical, the expansive force will be enough to push the dent, but not enough to wreck anything, because it can always expand up the tube as well. If that doesn't work i can try filling it 91%.

There's the anecdote about the frame builder using a hydraulic oil pump to pop a dent, so i don't see why this couldn' t work. Also given that that required drilling and tapping the tube which gives a potential point of failure, this method seems a bit more elegant.

Anybody want to see a pic of a split tube (aluminium) by someone trying something similar over at mtbr?
http://forums.mtbr.com/showthread.php?t=431970

 

[Russell]

Anybody want to see a pic of a split tube (aluminium) by someone trying something similar over at mtbr?
http://forums.mtbr.com/showthread.php?t=431970

Thats a fantastic thread!

 

[Err]

Seems that this freezing trick might just work. Read quite a bit about it for removing dents from four stroke exhaust pipes. One problem may be getting it in a freezer, but i intend to cheat and use dry ice.

See here http://www.thumpertalk.com/forum/archiv ... 69902.html

 

[FairfaxPat]

A long time ago I owned an Eddie Soens chrome plated track bike with a large dent in the top tube. Joe Breeze fixed it for me. He had a fitting he'd made which was a solid plug to insert in the head tube. This plug had an L shaped hole through it that went from the top (when inserted in the head tube) to a right angle turn to come out at the middle of the top tube. The hole in the plug had a relief cut and an O-ring inserted for a seal on the inside hole and was drilled and tapped for an automotive grease gun fitting on the outside top hole. With a drill he made a hole inside the head tube into the top tube and lined up the fitting with it. Then he filled the top tube of the frame with oil, re-inserted the fitting and used a grease gun full of grease on the other end of the fitting (the outside top) and pumped up the pressure until the dent popped out! All that was left was to drain the oil out of the top tube and reassemble the now perfect bike-even the chrome was perfect!

 

[Err]

Aha, so no hole to be filled after in the top tube!

Cool.

 

[shovelon]

A long time ago I owned an Eddie Soens chrome plated track bike with a large dent in the top tube. Joe Breeze fixed it for me. He had a fitting he'd made which was a solid plug to insert in the head tube. This plug had an L shaped hole through it that went from the top (when inserted in the head tube) to a right angle turn to come out at the middle of the top tube. The hole in the plug had a relief cut and an O-ring inserted for a seal on the inside hole and was drilled and tapped for an automotive grease gun fitting on the outside top hole. With a drill he made a hole inside the head tube into the top tube and lined up the fitting with it. Then he filled the top tube of the frame with oil, re-inserted the fitting and used a grease gun full of grease on the other end of the fitting (the outside top) and pumped up the pressure until the dent popped out! All that was left was to drain the oil out of the top tube and reassemble the now perfect bike-even the chrome was perfect!

That's a great idea! I learned something today.