Dale,
Having done dozens of tube replacements on brass brazed frames including Hetchins, Cinellis, Masis, and Colnagos all with delicate cutouts in the lugs and filed thin; I can say that it is possible to do these things singlehandedly using one single tourch. Sometimes a "rosebud" tip is neccessary but often it is not. Like I mentioned, there are a few tricks to making this happen, but the result is an extraction that leaves almost no excess brazing material behind and a joint that is nearly ready for refitting of the new tube. It's a thing of beauty to be sure. Like you said, repairing a frame is more difficult than building one by far. I was going to demonstrate the tube extraction at the Cirque but not nearly enough time nor the proper conditions. I guess the secrets will be buried with me.
Brian Baylis
Walk quietly and carry a big tourch!
>
> As a longtime student of frame building and an infrequent builder (31 to
> date and losing!) I am most admiring of builders who can successfully repair
> frames by "pulling " apart lugs and keeping everything more or less intact.
> This is MUCH more difficult than building a new frame. In fact, frame repair
> in general is a real pain and time sink....
>
> As Phil said, first the assembly pins must be dealt with.
>
> In the CR list we recently touched upon the technique of hearth brazing
> rather than a hand held torch.. This is a case in which the entire joint, all
> of the lug and tube ends, are heated uniformly and the joining material
> (brass/bronze?) is more or less molten at the same time... This overall
> heating is what must be achieved to successfully disassemble a lugged joint.
> The builder (un-builder?) cannot use a hand held torch and heat one side then
> the other to pull the parts away effectively. I remember Mike Melton
> recommending a "rosette" head for the torch to try to heat the whole joint..
> I have also seen a double headed torch with one head & flame on opposite
> sides used. Even with these devises, it takes a heck of a lot of talent to
> get the joint apart with frying the lug tips, etc.
>
> After the lugs are "freed" they are usually messy with uneven blobs of brass
> in and out and much clean up is necessary to have a nice piece with which to
> start building again.....
>
> Dale Brown
> Greensboro, North Carolina