I am currently in a welding school, and I just finished Shielded metal arc welding in both plate, and pipe. I'm not exactly sure what my problem is when it comes to "suckback", and proper penetration, and adequate fusion in the back.

I'm using 1/4 inch plate, no landings, cut at a 30* angle, and a root opening a little bigger than 3/32. For my artillery, I've got a 3/32 Tungsten, a #4 Cup size, a stickout a little bigger than an 1/8th. I've read that it's best to keep the Tungsten electrode right dead in the center, so the cup rides on the bevel of both plates. The arc length is suppose to be at about 1/16th. That's ******* tight! Do I just lay the filler metal right into the root at a 45* Angle, and push right into the root as I go over the filler metal with the tungsten electrode in a really tight motion ?

I'm not exactly too sure about the angles I've started out with, but when I did it my first time I had so much suckback, it was ridiculous. I've looked at a couple of videos, and only managed to find this one. This guy looks like he has major suckback as well.


my instructor was telling me that the back is suppose to be a long strip, bulged out, with not much metal solidification reinforcement.

 

A couple of things:

-If you're using a 3/32 gap, make sure you're using a 1/8" rod.
-You'll probably want more than 1/8" stickout. Usually when I'm doing full pen pipe/plate welds, I have 1/4" or more of stickout.
-You can lay the rod completely flat in the groove, or hold it out. 45* is far too much. 10-15* max.
-If you're getting a ton of suck back, you're probably running way to hot. You don't need more than 80-90amps for a full pen root. Then, on the hot pass, jump up to 125amps.
-1/16" arc gap sounds like a bit much. usually 1/32" or tighter. If you have too much arc gap, you will get suck out as well.

 

Figured it out today! I don't know about 125 amps for a hotpass, but I tried the hot pass today and it came out fine at about 100.

I do highly appreciate the input though.

There was a pretty cool instructor that came in today and showed me a couple of things. After giving it a shot on his settings, the root came out freakin' perfect!