undercutting

admin

when you are tigging, is undercutting always bad? If you have a thick piece to a thin piece do you still want to build up from the the thin piece? thanks.
Reply:Undercutting is operator error.  I do it sometimes.  With Stick or MIG, its from not pausing and allowing the filler to fill the base plate you burned into.  I get it with tig and even asked Mr. Zap.  "Not enough filler" which is the same answer as with stick and MIG.  I think with me its torch manipulation too.  If I didn't move it so far to the edge of the weld and let the filler flow there, it would not undercut as much.  Could be because I got this new 425 amp machine and need to learn to back off a little more.  LOVE that power.If I have a thick piece and thin, I work with the thick and put most of the heat there.  Can't see any other way.DavidReal world weldin.  When I grow up I want to be a tig weldor.
Reply:Undercut can be dealt with in diffrent ways..Like anything "liquid" the puddle likes to go with gravity..Metal is no exeption..If you can "even out" what your doing..Like adding a gussett to a plate..If its at all possible try to weld the joint on an angle like a "V" (of sorts)..But if you cant do that then aim the torch more to the bottom of the joint and add the wire from above.. And dont be shy with it.. All this will be gone over in class...... ...zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Undercut is bad because it acts as a "stress riser" and will tend to be the origination point for a crack, particularly under cyclic loading.