Qn: What size tip is recommended for
doing general frame work?
Ans: Sorry, can't remember the number, but it's a pretty
small one. Oxy-acetylene flames are VERY hot, so you can
easily overheat the tubes and weaken them.
A related tip: the brass will go to
hotter parts of the joint - keep the flame slightly ahead of
where you want the next bit of brass to go, and keep the job
turned so the brass doesn't all flow down hill if you're
doing fillet brazing (with no lugs)
I've also found it useful, when brazing two pieces of
different weights, to turn the flame to heat the thick piece
more, and even to shade the thin piece with the rod for a few
seconds to stop it overheating while the thick piece warms up.
Practice makes perfect yes, but brass is quite forgiving -
you always know when your joint is good and when it isn't.
- From: Matt Houle
To many brazers don't understand the importance of vent
holes. Let's say, for example, that you are brazing the
top tube to the seat tube, and you have already brazed
the top tube to the head tube. While heating everything
up to get to brazing temp., you are also heating up the
air inside the top tube. You need a vent hole (at least
one) to allow the heated (and expanded) air to escape. If
you don't, it will be difficult to complete brazing the
two tubes together properly. This is because the air will
keep trying to push its way through your brass or silver
as the filler cools. This isn't a problem with Tig
welding, because the joint cools to below the melting
Earlier, I said at least one vent hole. Be sure to use
two vent holes (water bottle bosses only count as one) if
you want any water that gets inside to be able to drain
Thursday, 29 January 2009