i tried a brass joint yesterday with (i think) pretty good results. the joint definitely helped me relax and take my time with heating. also i turned out all the lights for the first time, which helped as well. there was still some ambient light coming from other parts of the shop, and plenty from the torch. i'm _starting_ to get the hang of this.
this was the first test of the aforepictured tube holder, and it worked well. there's a fair amount of slop between the pipe attached to the pliers and the vise, which was only bad when i wanted to precisely position a tube.
the reason i wanted to do that was kinda silly. i'm running low on lugs, only 3 Rivendells left, so i tried brazing two tubes together without a lug, just letting one rest on top of the other. i tried to pin it, by drilling down through the top of the mitered tube, but the nail wouldn't go in right and the flux was drying so i just let one tube rest on the other. this required positioning the bottom tube horizontally, as i discovered when the top tube slid off when the flux heated up. i re-positioned and tried again, and the brass seemed to flow pretty well, except in one spot where i think the miter was off and the tubes were too close.
today i cleaned the flux off a bit and tried some destructive tesing. i held the unmitered tube in the vise and stuck a bar of solid stock into the mitered tube. it pried off without a whole lot of effort. i guess that's the reason for a fillet.
things seem good here.
that big black blotch there isn't so nice. i could tell when i was heating that i overdid it in one spot; i think that was it.
note the hole in the upper tube where i had tried to pin.
you can see a little line of brass around the inside there.
the weird red coloration appeared after soaking in diluted toilet bowl cleaner for a few minutes. today i tried soaking in pure T.B.C. for about an hour with better results. the flux came off quickly with some convincing from a file, although i had to emery off a lot of rust.