TIG Machine Settings

[BigPoser]

Hi All,

I acquired a Lincoln Precision TIG 185 a while back and am finally getting everything set up and getting some practicing in. My torch is a 17 and I also have a water cooled torch with a cooler (20) although I haven't used it yet. The welder has pulse, which is cool to play with a bit.

I've been working with the settings, but can't seem to find the sweet spot and keep blowing holes. I want to ask the TIG Gods what settings are generally best for welding thin walled tubing. What kind of amperage, to pulse or not to pulse, etc.?

Any tips, advice, etc?

Thanks in advance.

Brandon

[abbeyQ]

Blowing holes in your material isn't a machine settings issue, it's a technique issue. You're sitting in one spot for too long, building up too much heat and then you get the hole. Go faster. But generally you're probably going to want your amperage set ~100 amps and control it with the foot pedal from there. Some people like to fidget with their machine amperage a lot and others leave it alone and use the pedal for everything. Don't worry about the pulse for now, it's just another set of variables to chase.

And if you haven't already, start practicing on some thick material > 1/4" thickness. This will allow you to really pour some heat into the material and figure out what in the world is going on with the whole welding process. It makes things a lot easier before you shrink it down to the size of a pencil eraser.

[BigPoser]

Thank you Jason. Yes I picked up some thicker material the other day and I'll start playing with it until I can get better with the technique.

[Ahmdo Molah]

...
I've been working with the settings, but can't seem to find the sweet spot and keep blowing holes. ... what settings are generally best for welding thin walled tubing. What kind of amperage, to pulse or not to pulse, etc.?
...

Can you clearly see a shiny molten puddle? Can you determine if the puddle is too thick(not moving easily) or if it is too hot and boiling(bubbling and swirling into the center)?

If you cannot clearly see the above, then you are limiting yourself of critical feedback. Once I added a X2.5 magnifier lens into my auto-darkening welding helmet, my welds improved significantly.

When you can clearly see the shiny puddle, you can immediately determine if it is too cold(thick) or too hot(boiling), giving you the feedback to pace your arc and/or adjust the amperage.

For thin wall tube welding practice, I started by using inexpensive seamed tubing 0.9mm (0.035") thickness 1" diameter tube ("closet/clothes hanger pipe"). As this was cold-rolled (no dark oxide layer to remove), only an acetone wipe down was required. For filler, I used 0.9mm (0.035") ER70S-6 MIG wire cleaned with acetone until no residues were detected on the wipes.

For welding small lengths(a couple inches) of this tubing to itself without internal heatsink or purging, I started around 50amps, no pulse. The steep angled(e.g. 90degree joint) sections require more amps(5~10). You could hold the arc longer without raising the amps but this puts more overall heat into the joint as the HAZ will show later through a dark blue or worse grey(cooked) color. I've found that raising the amps in these nooks and maintaining the pace is better. If the amps are too low and/or the tungsten tip is too far from the root, penetration into the root will be hampered (there will be an air pocket 'eye' at the root peering at ya).

If you move onto using an internal heasink and purging, your amp settings will have to be raised initially(perhaps 10~20amps or more) as the heatsink will initially suck up a lot of heat until it is saturated, at which point you may want to lower the amps.

Also in the narrower (steep angled) sections, the arc will want to wander* to the side closer to the tip of the tungsten or the side that is closer to the grounded side. If the arc leans to one side, penetration in the root of the joint will not be possible. The best way to resolve this is to get the tip of the tungsten as close to the root without dipping into the puddle. With magnifiers I am able to get as close as around 1~2mm, slightly raising the tungsten when I dip the rod(Jody style).
* Magnets will also throw off the arc in weird directions and should be removed from the workstation.

After getting a good feel for laying down pretty welds with good penetration all around(after about a year or two of intensive practicing almost every day), I moved onto pulsing, and after another 6 months to a year of intensive practice I could do both methods (pulse and non-pulse) well. The reason I recommend working with pulsing later is that with pulsing, the puddle exists for only a fraction of a second, and the allowed reaction time and visual feedback for the operator is that much limited, for doing what is required for a sound weld with good penetration, as opposed to just laying down pretty but cold beads that maybe stuck on there like gum under a seat.

When pulsing with 'lay wire technique', I noticed that if the amps are too low, the rod will feel 'sticky', and this can be frustrating as the tip of the rod will scoot and stick in the wrong place more often than not. When the right amp setting is dialed in, the rod tip aimed at the thinner of the two tubes and the tungsten tip aimed slightly closer to the thicker tube, the rod will flow like butter from the thin tube to the thicker tube and the penetration will position itself in the root. With magnifiers, I can see the split second puddle, movement of the molten filler spreading from the thinner tube through the root and onto the thicker tube before solidifying, and position the tip of the rod again (on the thinner tube) just ahead of the bead that has formed. Without a good amount of time observing the tiny puddle continuously, I think it is likely that one would miss the fine details of what happens in that split second of a pulse.

Cheers~