Brazing

afternoon folks. i was wondering what the crack is with removing braze ons? i have a couple of brake cable guides i want to remove. the frame is chromoly butted and the braze ons have this gold coloured braze material around them? is that bronze or something? can i just fire up a normal blow torch and melt them off and tidy up with a file or does it need something special? frame is stripped of paint ready for respray and thought it'd be nice to take them off. any ideas would be grand. cheers.

if all else fails....

Coat them in fish paste or cream cheese, and get a cat to lick them off.

there's been a couple of threads on this. heat can potentially cause problems i think, so the best way is to use a hacksaw (or an angle grinder) if you must, then tidy up with a file.
asm can help you out with all things related to angle grinding ;-)

gotcha, found the threads cheers, should have searched first. im still learning that other people miht have had the same ideas... seems the angle grinder wasnt a joke then, scarey. i'll see what i muster up the courage for and if it works out fine i'll share the knowledge.

just get a small hacksaw, take your time, take it close to the frame, then file off the rest.

i bottled it. got the blow torch out and heated it a bit and pussyed out. ah well, another time when im not in a rush i think i might try the hacksaw method.

STOP! put the torch down!

yes they are brazed with brass, and no heat is not a good way to take them off.

1 leave them on, it will save a puppies life, and there is no reason to remove them.

2 if you must remove them get a mini hack saw and aim for the top of the brass, or bottom of the guide depending on how thick the brass is, carefully saw through, then get a file, and work down the brass, then finish it off with some sand paper and emery cloth.

:)

I should say that the only thing that heat will do is weaken your frame.

heating introduces oxygen to the metal making it harder but more brittle, good for the tips of blades like saws and knives but not for frames.
i think its something like that, or it introduces carbon to it. either way. makes it more brittle.

it depends on the amount of heat, if you get it hot enough you heat treat it which makes it stronger, but if you don't get it that hot (or get it that hot in one point, but cooler around it as a torch does) you are weakening more then you are strengthening. Also bike tubing is quite thin, and easy to burn a hole through if your not careful, or don't know what your doing.

heat treating makes it harder, but more brittle. stronger ? i think the frame would be more susceptible to cracking at that point where the heat is introduced coz the frame would be more reluctant to bend as it would do had it not been treated.

it depends on the amount of heat, if you get it hot enough you heat treat it which makes it stronger, but if you don't get it that hot (or get it that hot in one point, but cooler around it as a torch does) you are weakening more then you are strengthening. Also bike tubing is quite thin, and easy to burn a hole through if your not careful, or don't know what your doing.

c'mon chris, you should know better than making broad brush statements like this. Heating can do two things dependent on what follows: if you cool the metal fast it goes harder but more brittle, cool it slowly - in warm air, say - and you can make it softer and less brittle. Fast heating or cooling make the metal structure less predictable if I remember correctly.

Chris, I agree with the point about spot heating, you can set up stress points in the metal. Metal that is already stressed then has additional tortional or bending stresses while being ridden is most likely to fail in the pre-stressed region.

c'mon chris, you should know better than making broad brush statements like this. Heating can do two things dependent on what follows: if you cool the metal fast it goes harder but more brittle, cool it slowly - in warm air, say - and you can make it softer and less brittle. Fast heating or cooling make the metal structure less predictable if I remember correctly.

I doubt the OP was would have been flash cooling the frame, I was speaking to circumstance. But yes you are right and i should have pointed this out

You just don't need an anglegrinder or heat to get brazeons off, it's like using a rocket launcher to open a can of beans.

Junior hacksaw + file = win

Bollocks. Angle Grinder all the way and a neaten up with a file.

HTFU and use a hand tool pussy. Did chopper use one of these on his ears? Did he bollocks.

The more risk of losing body parts in the process the better the tool.
It's a simple fact of life.
HTFU.

Kick them off.

:)

Kick them off.

:)

I just took to uk my old and loved frame.
unfortunately the people moving luggage at airports are worst than what I thought and even if I packed up the frame properly they managed to damage it. bastards. however, fortunately it's not dented or flattened but it's just a small rip on the tube of the drive side of the chainstay...
speaking with the guy who made the frame in Italy the best thing to do is to put a few drops of brazing rod on the "cut", file it down and re-paint the frame. he was telling me it should be a cheap job (20-30pounds?) and should be as resistent as before...

and this is the frame:

any thoughts or advice??