defiling lugs

bilaminated construction is SO it right now. since i can’t afford the bilaminate dinner, i opted for the quarterlaminate lunch special. all yuks aside, these are three in process photos of some kind of brass brazed construction. instead of having a fillet totally encapsulate the downtube, there is a half-moon fillet along the tip of one lug point to the tip of the other. working out my inner rene singer of course.

in this first photo, the lug has been completely brass brazed. i’m using gasflux type b flux and gasflux co-4 low fuming bronze rod in 1/16, to flow a smith aw2a torch with a 205 tip. the flux has not been cleaned off this joint, and i’ve started step two of the brazing process for this particular lug. starting at the tip of the lug curve on the dt, i’m about to lay some fillets over both the lug edge and the tube itself so i can blend them into that “half-bilaminate.”

in the next photo you can see the fillet line. more important than perfect fillets here is the timing of laying them down, as this is all done in one heating cycle of the joint. temperature control is necessarily the name of the game, and the little puddle fillets are floated down over the top without flowing out the brass from underneath the lug. i’ve already started bulk cleanup on one side of the fillet line.

and this third photo is of the joint after being thinned and shaped with a 10″ half round bastard file. the tube itself has been scraped with 60 grit cloth to help give me visual clues for a smooth transition. the “shoreline” area that is left underneath the fillet arc has not been touched yet. in the photos to follow, the finished lug will blend out of the tube on the top, and underneath the shoreline will pop out.

just a few laughs in the cicli polito kitchen. this is a bike for skip, and he said “make it interesting.” if you’re interested in more photos of the build, please view the in-progress photos at flickr


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