Gas Welding Refresher

[Mrwurm]

Last summer I bought a gas welding rig for cutting and heating parts. I got some rosebud tips for heating, cutting tips, and a #1, #2, #3, and #4 welding tips. lately I've been toying with using the #4 welding tip to weld some 1/4 stock. For quick jobs I thought it would be easier to fire up the torch than to drag out and set up the stick welder. Heres the trouble, I can't get the metal hot enough to melt or puddle. The last time I welded with gas was in High School. My regulators are supposed to handle enough flow to run the #4 tip. Am I forgetting some fundamental for adjusting the flame or pressures ?. Any thoughts out there ?

 

[centex]

You need a larger tip. Try a 8 or 9. I have Harris torch so the numbers may be different for Victor. If you get pops you need to go larger. I would not try to weld 1/4" with gas. There is just too much heat involved. I only use gas to weld sheet metal up to 1/8". If you have a stick welder that is the way to go for what you want to do.

 

[Mrwurm]

I did some checking and a #4 welding tip is supposed to weld 1/4 to 1/2. I am using victor style tips. An #8 or #9 tip will weld up to 2 inches. I think the problem is that I have not been setting the pressure high enough to get the right amount of flow. I have pretty small tanks so I have been cautious about exceeding the 1/7 withdrawl limit for acetylene.

To explain, I have a stick welder and 220 line in my garage, but I don't have a 220 line in my barn. I do most of my fabricating in my barn so I thought if I could tack weld parts in my barn with the gas welder, then I could move the lightly assembled parts to the garage for stick welding.

 

[Ozarker]

Without being there to see what is happening. my first thought would be that you have what is commonly referred to as an "Oxidising Flame". That happens when you have too much oxygen to the flame. The blue cone in the flame is shorter and sharper, the flame seems to hiss more and you get excessive sparking but little fluidity in the puddle. A very difficult condition to weld with.

Try backing off on the oxygen until you get smoking (Carburising Flame) and then slowly add oxygen back until the center cone of the flame just rounds off. Then stop and start welding.

If you can't weld it at that point then there is one of two things happening. 1) you really don't have a large enough tip or 2) Your heat is being absorbed and taken away by something under your work.

Many people often make the mistake of trying to weld with gas wile the stuff they are trying to weld is laying flat on a metal workbench or clamped in a vise with the joint too close to the vise. The bench or vise will act as a heat sink and rob you of the heat required to make the weld. Make sure there si nothing under or near your work that is sucking your heat away.

 

[Mrwurm]

Good points. I have definately been getting a lot of 'popping'. The torch also seems much louder than I remember from my high school shop days. I will try your method for adjusting the oxygen in a few days. Also, I have been lying my parts on the concrete floor, possibly a good heat-sink. Thanks for the tips. I used to be pretty good at this stuff but I've been away from it for about 20 years.

 

[Ozarker]

Defiantly get it up off that concrete with some spacers of some type. Angle iron laid down to lay your work on works well. Even 2x4's work well if far enough away from the flame to not catch fire.

Concrete, if too damp from humidity, can actually explode in your face if it gets too hot from a torch flame. Remember your boy scout days and the warnings about using river rocks to line camp fires. Water in porous material like rocks and concrete can turn to steam and blow it apart when it is heated.

 

[Mrwurm]

Oops, there it is. The problem has been revealed. My parents would'nt let me be a boy scout. I was bitter, now sad. /w3tcompact/icons/sad.gif

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