[jc.considine]

I'm a newb but I've done a couple of projects, like a full aluminium 'cage' roof rack for my 4WD.

Whenever I weld mild steel the arc is so bright when I start that I get a patch in the middle of my vision which is hard to see through (which makes it difficult to judge the arc position/length after that!). I don't get the problem when I weld ally though.

I know I'm doing something wrong.

My setup is: pure argon, 2% thoriated 1/16" tungsten, gas lens, water cooled #20 torch, 60 amps dcen. My welder is an inverter with HF start and I usually start my arcs at about 1/8" off the material. My auto darkening helmet is set at DIN 13.

The 1" x 1/16" wall tube steel I'm working with at at the moment is what we call 'black' steel over here (Australia), it comes with a coating of oil and that's it (though I got the same issue when i was working with galvanised tube that I'd ground back when I was building the balustrading for my kids tree house). My prep for the black steel is to degrease it with a hydrocarbon solvent, wire brush the weld area with a stainless steel brush that's only used for mild steel, give the area a wipe with acetone, then finally hit it with a butane torch to combust anything that's left, and preheat a little.

anyone got any ideas?

Thanks,

JC

[ogorir]

off the cuff, I'd say that your autodarkening helmet's sensitivity is set too low. welding aluminum uses more amperage and therefore has a brighter arc, so it should trigger the lens. I've had a problem similar to yours switching from welding 16ga aluminum @ 90A to welding 22ga steel @ 30A. I bumped the sensitivity down for the aluminum, and when i switched to steel, the arc wasn't bright enough to trigger the dark shade.

so, quick check, is the lens changing to the dark mode? if it isn't, bump up that sensitivity and maybe clean the sensors off. if it is changing, I don't really know what to say, besides switch out your autodarkening lens module for a fixed shade #10 or #11 for that 1/16" wall tubing. all your settings and prep work sounds fine.

[gnabgib]

This once happened to me and I discovered that I had bumped the sensitivity knob to low, probably when pushing or pulling the helmet in/out of my bag. Not sure if it's that though. Also, why are you using a stainless wire brush on m.s. Not neccessary!
Cheers, Jeff in Oz.

[jc.considine]

Thank you gnabgib and ogorir; It was the helmet sensitivity. I thought it might have been a contaminant causing the arc to flare, but it was simply the helmet (and my newbness). I had never considered that the arcs for different materials could have different intensities, and I had the helmet set up for ally.

gnabgib, I use the ss brush because I like the shape of the particular brush (it's curved). It shouldn't be a problem though should it? apart from being more expensive...

JC

[ogorir]

no problem with SS brushes other than the cost. I use 'em for everything 'cause they're easier to keep clean and they last longer.

[gnabgib]

Ah...!?The old sensitivity knob problem. I don't spend too much time cleaning ms. and keep a s.s. brush only for the more sensitive materials. Don't mix them up.