Doug: Heat in this case will be every beginners problem and I appreciate the advice! This is why I'm asking hese questions
The Columbus Life tubing however I can't find any information on whether it's heat treated or not? Nor the other tubes in the Columbus range. Most of the Columbus range come in .7 butt wall thickness, there are some .8 and only a few .9 from what I've seen.
I took a look at Zona tubing for the main triangle with 8-6-8 for top and down and single butted 8-6 for the seat tube. With the same lugs and stays that would be 142 grams heavier. Adding chain and seat stays in Zona the number increases to 201 grams (with the same tube length compensation as earlier) That ends up as 1817g without taking the mittering of the tubes or any other braze onīs into account.
But how big is the difference between .8 and .7 when it comes to heating? When I've welded sheet metal on the car and compared 1mm with 0,7mm I can use the same current for the weld, but maybe only hold it for 3/4 of the time before I burn a hole. These spot welds when I get them right are almost completly flat.
However, that tells me that the difference in heat management between .7 and .8 shouldn't be that big. Given that the material is exactly the same of course. I'd say that I'm more afraid of underheating the connection than overheating to be honest :/
The temperature needed is also connected to which braizing material you use I guess?
Unterhausen: Fair point. I could buy a piece of the cheapest tubing in the same wall thickness as I'll use for the frame where I get all the other tubes and do a couple of practice runs before going to the frame!
Andrew: Then I guess you would agree that going up to OS tubing and steerer is a smart choice?
If I understood you correctly, would you say this method would be a "smart" begginners method: Take out holes in the lugs so that the distance that I need to "pull" the brazing over becomes shorter, and do only parts of the lug at a time. For instance do the top lug to the top tube first, let it cool off. Then the head side of the lug? It gives more heat cycles, but shorter ones. From what I've gathered so far, the heating should be kept to a small part of tube right at the lug and not spread out over the tube to get the heating more evenly increasing over the tube lenght? I guess this is to keep molecular movementas concentrated as possible so that the steel wont shrink/pull over a longer section of the tube?
Wouldn't pre heating the entire tubes in say an oven make this process easier in that case? The heat difference between the non heated parts of the tube will be smaller (bronze melts at almost 1000 degrees C, preheating the tubes to say 200C is 25% less heat difference) giving a larger window for error?
By the way, silver or bronze is mainly used for brazing. Is there a reason for this? Aluminium for example melts at a lot lower temperature. Is the 950-1000 degree celsius needed for something else than actually getting the "filler" to melts throu?