here is an exposé, lesson, safety net, and more, rolled into one atmo. i have been brazing up forks on and off for two days and had about 10 in the bag when the last unit was loaded in the fixture. i prefer doing some things one at a time, and other things en masse. data point - en masse does not mean in massachusetts. since i have only been back to work for a week or so, i decided to light up all the blades. typical me, self-absorbed and shit, i was smarting all along the way with how well it was going despite my hiatus from the bench, and also reveling in how tight the tolerances and brazing lines were coming out. when i got to this last guy, i had the second-guess thing descend on me; mister second-guess is a guy you don't wanna meet when you make a frame, and especially when you are making a fork atmo.
when i completed the assembly task and washed off the flux, i noticed that the linearity reading using the M+L table told me that the center-line of the tips, though at a nice 101mm OLD width, was over to one side of the steering axis by nearly 2mm. that falls outside of my comfort zone with respect to what i would willingly align into spec. but, to borrow a phrase that pal CPG often used, "but that's just me". i guess if it was a B model (sic) or a team frame, i might have leaned on it and showed the fork who's boss, especially since it was the last pair i was gonna braze for a while. but second-guessing won me over and i decided to sacrifice the fork in the name of low budget R and D. for me here at the new presidential palace, that means destroying the fork and seeing how far i can bend anything bendable before something appears truly broken. in short, despite the alignment issue, i want assurance that the brazing will stay intact until i can't push and pull any longer.
the pic set on flickr was loaded in order. i shot close-ups and at regular distances so you could see what i saw. the long and short of it is that once the tip width got to near 12", i couldn't get the blades any further apart for fear of tearing the bench out of the wall, or breaking my elbows trying. the entire sacrifice was done with the steering column firmly clamped in the bench vise. only after i got to the 12" mark did i begin to see a slight blem (i used MS paint program to make it clearer for you to view. notice the red marks on some of the later images.) that could be considered the beginning of brazing shear. NOTE: this only appeared when the front fork tips were nearly a foot apart from each other. when i was done strong-arming the sucker, i sawed the blades off and tried to take some pics of the inside fillet, or whatever it's called.
for the record, i used a straight gauge 1.6mm steerer, columbus SL blades, and BAg-7 (56 percent silver alloy) brazing rod. this fork, while it was out of spec after cooling, probably could have been safely pulled into alignment for the 1-2 millimeters needed and not really sweated the consequences. but seeing it come out post brazing a whopping 2mm over to one side raised a red flag here. hey - what color did you expect it to be?
cheap insurance atmo.
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Fuck up friday
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Originally Posted by steve garro
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