What do you use to smooth the brass down? A file, or sandpaper, or a flapwheel or something?
All of the above. Start with an angle grinder for the places where I laid it on thick and gently bring the high spots down. Then with the same angle grinder switch to a flap wheel with 80 grit and bring it down a little more. It is very easy to screw up with the grinder so a little at a time is best. Then I hit the corners and tight spots with a dremel and then a file. Then just use sandpaper. I like to use a roll of 80 grit that is for a belt sander and cut it so I can pull it back and forth across the tubes. It is alot of work. It really makes you appreciate what the masters like Steve Potts and Tom Ritchey can do.
feel free to tell me to go to hell if you wish, but
If you use the Curtis method, you can save yourself hours of tedious filing
three days before I did this, I'd never so much as picked up a torch. the trick is to get a much smaller flame in much closer, accurately controlling where the heat is, the brass flows naturally into a nice neat fillet that way!
Plenty of big name framebuilders use the methods you do, But i guess they just enjoy filing more than Brian Curtis does