[TheForge] Welding cast iron

[Washington, Aubrey O.]

Todd, I hope we get some snow.  It sure has been dry around here!  But, so far the sky is clear here in Norman.  How does it look over your direction.
 
Bruce, thanks for the link on cast iron welding.  Based on what they say, it looks like brazing may be my best bet.  I have done very little brazing, so I could use some input.  Here's what I'm thinking of doing:
 
1.  Clean the area around the break as well as I can of 90 years of grease;
2.  File a V groove on both sides, leaving a little of the original in the middle to index the pieces;
3.  Clamp or wire the two pieces in position to a convenient length of bar stock;
4.  Heat the whole set-up to 900* or so in the forge;  (Why do they say not to use propane?)
5.  Braze the joint using the O/A torch; probably in several passes, alternating sides.
 
Here are a few questions I have (so far):
1.  What kind of brazing rod should I use?  The flux coated kind you get at the hardware store?  Bare rod dipped in flux?  
2.  If I use bare rod, what kind of flux should I dip it in? 
3.  Do I put flux on the ends of the broken piece, or just on the rod?
4.  How do I tell when I get the preheat to 900*?
 
I'm sure I'll have more questions later.
 
Aubrey
18 degrees but no snow in Norman