Tig Questions I hope you all have answers

By lazydwoodworks Date 10-19-2007 16:51

Hi, here is my problem I am currently enrolled in a welding program at the local community college and taking Tig and Advanced Arc. Well my instructor lacks the Tig knowledge to help me with my overhead welds. Tig overhead is not his strong suite, he tried and it looked worse than mine. I am currently trying to weld 10Ga. MS with a 3/32 opening. I am either to cold with no pen. or to hot with suck back on the root side. We are welding with a IdealArc 300, water cooled, with foot control. I say w because another student and myself are having the same issues. I just cannot find the sweet spot to make the weld. I have tried the laywire and dip techniques, and have better pen. when I dip the filler metal. I have tried both 3/32 and 1/8 filler rod, I cannot tell you the classification on the rod because the boxes have lost the labels. Could the filler rod be part of the problem? does anyone know where I can find a chart of the the last characteristics in the ER70S-xx ie(ER70S-D2) I would love to understand what the last two digits in the classification mean. THanks for all the help in advance.

By Kix

Date 10-19-2007 17:30 Edited 10-19-2007 17:38

To get penn above flush with the base metal in the overhead positon on 10g sheet metal try this. Bevel the 2 pieces down to a knife edge. A 35+ deg bevel would be best to give you some room to work. Gap the joint to whatever size rod you are using. 1/8'' would be easiest. Now this might sound confusing, but you need to gap the end of your joint wider then the begining because it is going to close up on you as you get closer to the end. Lay the 1/8" rod in the gap and get comfy and start melting that filler rod. Only use enough heat to melt the rod and then just a bit more to get you some good tie in to the base material. This will require 2 passes in the overhead. The key is to get as comfortable as you can so you are real steady.
Or you can do it the way you've been doing it with a slightly bigger gap and really shove that rod up in there. Thats the tuff way. The last 2 XX in those classifications are for chemical composition of the rod. If you are using a rod with a -D2 on the end of it your going to have to be on your game to keep it from sucking back. It is a very runny or fluidy rod. Just run it as cold as you can and that you still tie into the base metal.
Or you could throw your teacher for a loop and butt them straight together and fuse them with no filler and no gap. Your going to need to slow down so you start to melt the back side. Don't get it to hot or go to slow or you will suck it back this way as well.
Did your teacher have you do any oxy-fuel welding before tig?

By bozaktwo1 (***)

Date 10-19-2007 18:05

The way I learned was with 1. a whole lot of scrap and 2. a whole lot of scrap. Get your amperage and manipulation down on flat metal; no root. The start with groove welds, starting with almost no opening and work your way up from there.

By lazydwoodworks Date 10-19-2007 18:46

Thanks for the advice I will try these techniques on Monday. We did Oxy-Fuel my first Semester, but we did not do overhead. Now I am wondering why, it might have helped. I have passed the Horizontal, Flat, Vertical Open Butt test but the overhead is giving me problems. I will keep you all informed thanks again for all the help

By fbrieden (***)

Date 10-20-2007 02:12

Find an instructor who knows what he's being paid to do!

By strat

Date 10-20-2007 03:33

lazydwoodworks,

is your instructor showing you how to walk the cup or are you freehanding?

By Tommyjoking (****)

Date 10-22-2007 07:02

lazydwoodworks Kix has given really good advice here ....lay it up there and just have the heat on the money for tie in.....doing it that way leaves the best looking backside. One thing you could try is do a test plate and run about two inches with your foot floored (or about 90%) if it don't look good turn it down and keep doing that until with your foot all the way in you get a good looking root. Overhead with a foot pedal on a long weld can be difficult at best...if you get that topend set just right you don't have to worry about balance so much. If you go for the shove it in there method (harder to pass xray) you need heat and good fast travel to get that root to stay above the surface and shoot good.

Good luck and tell us how it goes
Tommy

By lazydwoodworks Date 10-24-2007 19:33

I am free handing the weld and studying up on walking the cup. The day time instructor is lacking in Tig Knowledge. The night class instructor from what I have been told has a greater knowledge of Tig. So I may try and catch the night instructor and get him to help me. For the time being I am working on Aluminum and Stainless. Next week I am going to try overhead again. Thanks for all the help.

By Flash Date 11-21-2007 10:05

Hey Lazywood
I agree that foot pedals are hard work in any position, particluarly overhead
a few tips for you that mighthelp
remember that tig is uniqiue because wire feed and amps are independant
most people weld on low amps because they do not add enough ice to the fire
the more wire (ice) you add the cooler the weld pool (fire) gets
so crank the amps and keep the wire inthere
welds go in molten, so if sucks back add the wire higher in the joint even behind the root so when it sucks back it is flat
another point is generally it only sucks back when you pull your wire out when dipping
so do not pull it out and it helps prevent suck back, by keeping wire in there it helps with weld ool surface tension and stops suck back
have fun
R
JJFlash