Gas Lens Question

[MCoupe]

I have a new PowerTIG 185, with the new flexible 17 torch, running 110 volts. I have gotten rather good at laying a bead on flat steel, though my success with filler rod is only adequate so far. 100% argon @ 7 LPM, #4 cup, red 3/32" tungsten, Weldcote ER70S2 3/32" filler, 1/4" protrusion sharp tip, steel cleaned with chemicals then brushed immediately beforehand, 80 amps, 1/8" plate. So I thought I would try a gas lens setup. $30, and I'm trying a #6 cup. But an arc doesn't start quickly, and when it does it immediately gets dramatically larger and brighter than it should (than I'm used to), even when lifted well off the plate. Too bright to see the puddle, and I have darkened my faceplate. Bad setup? Advice would be much appreciated.

Chris

[zoama]

Sounds like air is being drawn into your shielding gas. Check all connections especially around the cup and back cap.

[RichardH]

Zoama,
I've heard conflicting info - one, that a gas lens requires higher flow rate (or is that just presuming you're using a larger cup with the lens?), then there's CK's claim that their "Gas Saver" lenses reduce gas consumption by 40% (which must mean you turn the flow down).

Would this symptom happen if the flow rate was just too low?

[zoama]

Zoama,
I've heard conflicting info - one, that a gas lens requires higher flow rate (or is that just presuming you're using a larger cup with the lens?), then there's CK's claim that their "Gas Saver" lenses reduce gas consumption by 40% (which must mean you turn the flow down).

Would this symptom happen if the flow rate was just too low?

5 to 7 lpm would be right for a #6 cup. Pictures always help the diagnosis. The more detailed the better.

[performance]

The 4 cup is too small. Lifting the arc up off the metal will make the arc brighter.

[Kempy]

I use gas lens all the time you can stick the tungsten out the size of the cup with no problems #4 out 1/4" @5LPM, #6 out 3/8" @ 6 LPM and when I stick it out more I put it up to 6LPM #4 out 3/8" and 7LPM with #6 out 5/8" to 3/4" for getting into tight spots and never had any problems on steel. One thing with electricity the bigger the gap the hotter the arc then the tungsten gets brighter with in reason pull away makes more heat keeping it closer will concentrate the heat to a small area and not be as bright. As Mark said also (Lifting the arc up off the metal will make the arc brighter)

[Paul Moir]

I'm with Zoama; the difference in welding with a gas lense instead of a regular cup should not be at all dramatic. The big deal is you get a little less colouring with steel & stainless with reduced gas flow, and you can stick out your tungsten a *lot* more without causing problems. Other things indicate something else is going on.

[MCoupe]

OK, when I switch back to the normal cup it welds fine. Switching to larger aftermarket size cups works well, though with a bit of a flare on start - easily believed to be the teflon spacer letting air in. I can weld aluminum reasonably well, particularly given my skill level. Research, weak as it is on-line for this, shows that a 54N01 teflon insulator is called for. But this does not fit well with my medium (large) gas lens cups - too small for the cup-insulator connection. It is just the base of the cup against the large, flat base of the insulator. Is this normal? I now have a half dozen sized insulators, all I assume for the torch-insulator-cup juncture. Only one of which seems to fit but with the flaring. I have nothing for the torch-back-cap junction. I have tightened all connections to the max and still get the flare on use of the gas lens.

Chris