Framebuilders - Practicing fillet-brazing on steel plate

I'm currently learning fillet-brazing, and I need practice. I have a pair of about 1/16 " thick L-shaped steel sections about 5' in length (I think they came from the roof of an old shed). I was wondering whether brazing bits of those together would be a good way to practice fillet-brazing without needing to cut mitres. I'm already fairly good at mitres, so I don't need too much practice at cutting them, but at the moment, I have to cut one every time I want to practice brazing. My idea is to create a 90 degree joint with the two pieces, and braze it. If I simply practice on these L-sections, would the technique be close enough to tube brazing to be useful when I finally build a frame?

Any practice is good. I like your idea since you'de get immediate feedback on whether if you braze on one side the metal flows through and wets the opposite side of the joint. Try different angles too, as when you are joining tubing the crotches act differently from the sides.

Actually I just might do this but work on less than 90 degree joints (as the acute angle crotch on the seat cluster is my trouble spot.)

One thing that you might find different is the way the flame "flows" and bends around tubing is going to be different from the way the flame splashes out when it hits a flat plate. So when you go back to tubing you'll need to work on finding torch positioning that works best.

if it came from the roof of a shed, it probably is galvanized and it's unhealthy for you to braze it. That being said, joining any two pieces of metal together is good practice. Another thing to try is to find something 1/8" thick and braze it to something a lot thinner. I have all sorts of shop built tools that are brazed together. Hammer/Nail syndrome.

If those strips of metal were from a roof, make sure it isn't galvanized. Heating galvanized metal with a torch will give off toxic fumes - - really bad news.

was also going to mention the galv. that may be on it. Not great stuff to breath unless you want to take some time off your life and spend a week in bed sick. But ya, decent idea. Id stick with tubes however, go to a scrap yard, find some tube for 30 cents a pounds, as thin as you can of course, design a tv stand, or beer holder that needs mitres, and get to work. Maybe do a few you can cut apart to make sure you are penetrating the seem well enough. On a materials note. If you have access to esab stuff, try there flux for fillets. I doubt it is anything special, but comparing it to the characteristics of gasfluxes paste, i find i get more holding of the fillet on the metal, which really comes in handy while getting near vertical during the fillet, and also I found it yielded less porosity in the brass. It is a pain to clean off, but i feel its benefits warrants this pain. have fun.