O/A elbow to flange practice

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I will be making a fuel injector body to replace my carburetor in the near future.  It will involve a 90 degree elbow welded to two flanges, so I decided to get some practice in this weekend with a few test welds.  Time to break out the ole torch!see all photos: http://cell.dreamhosters.com/photos/elbow-flange-test/For the first flange I think I used too much heat, and consequently my puddle got too big (I started out with a #3 tip, then moved up to a #4, then a #5).  The problem turned out to be my torch angle (it turns out its pretty challenging to maintain a constant relative angle around a circular object.  Now I see why you guys use positioners...)The bead looks kinda messy.  I was welding about an inch at a time, then rotating the piece and moving to the opposite side.The second weld turned out a little better.  I figured out the torch angle and was able to step back down to a #3 tip, and controlled my heat much better.the finished product:The problem child turned out to be the spot in the "shadow" created after welding the first flange on.  I couldn't get a good torch angle there.
Reply:damnit i forgot to put the dime in the photos...
Reply:Looks okay for practice---next session, try not to undercut the welds:-less heat, more rod, go faster or whatever combo works for u.-as you probably have noticed, you'll need to use thicker flange stock to prevent or minimize severe weld pulling/distortion on the flange faces  Even with thicker stock, after welding--I'd suggest planning on surfacing the flanges flat on a belt sander (or carefully draw-filing), then checking flatness with a straight edge, over length, width and diagonally; for gasket sealing--which is critical for your application.-on the actual fitup, presumably you want or need a 90 degree plane, so during the tacking and welding, you'll need to check this squareness--as well as fixturing for the flanges to stay aligned to the horizontal/vertical, etc.........fitup's aren't easy--and that's where they separate the men from the boys.Blackbird
Reply:thanks for the tips dave -- luckily I have a belt sander so I can get the faces flush.  by undercutting, you mean the way the weld appears to "gouge" out the elbow a bit?  I was concerned about that -- do you think it would be better to use more rod/less heat/go faster like you mention, or do multiple passes?luckily, in my particular application a small throttle body will be hanging off one end of the elbow, so a perfect 90 plane isn't required.  The elbow is being used so that I can drill and weld injector bungs into it.
Reply:Looks great! a #3 tip seems a bit much, at least it would be on my Victor setup.A #1 or 2 would give you more time to control the puddle also take advantage of the torch angle to avoid that undercut Victor SuperRanger O/A                                         Solar migLincoln Powermig 140Southbend 9in lathe350# kohlswa anvilMiller Maxstar 150 stl etc....
Reply:while I'm at it, here's another question I haven't been able to figure out.  Sometimes when O/A welding my puddle will "pop", and sometimes its strong enough to blow out the flame on the torch.What causes this?  Am I accidentally getting the flame cone too close to the puddle?  Is it too much heat?  Or is it just the strange geometry of welding a curved pipe?
Reply:Originally Posted by cellwhile I'm at it, here's another question I haven't been able to figure out.  Sometimes when O/A welding my puddle will "pop", and sometimes its strong enough to blow out the flame on the torch.What causes this?  Am I accidentally getting the flame cone too close to the puddle?  Is it too much heat?  Or is it just the strange geometry of welding a curved pipe?
Reply:Originally Posted by cellthanks for the tips dave -- luckily I have a belt sander so I can get the faces flush.  by undercutting, you mean the way the weld appears to "gouge" out the elbow a bit?  I was concerned about that -- do you think it would be better to use more rod/less heat/go faster like you mention, or do multiple passes?luckily, in my particular application a small throttle body will be hanging off one end of the elbow, so a perfect 90 plane isn't required.  The elbow is being used so that I can drill and weld injector bungs into it.
Reply:Your welds look good and consistent width.These guys are right on.Popping can also be a result of improper pressure for the tip (too low). Also, change the angle of the torch. If the tip becomes more vertical you get more popping.The undercut is the first thing I noticed, too.  Hope you use that piece for practice.  Reweld over that weld.  Paying attention to where you place the filler.  It look like most of your undercut is on the elbow.You can also move the torch away from the metal to control the heat.  That corner hold a lot of heat, unlike welding a butt joint.