Erratic start with foot pedal

[performance]

"1/16 tungsten is WAY too small unless you are welding at something less than 20 amps, especially on aluminum. "
1/16" should be good up to 65A or so on alu or about 75 on SS. you'll probably want to put a land on the end of the tungsten for the higher end of any tungsten size's operable range.

you also might want to back the amps off, but if you're using a high high-to-low pulse current ratio, 98A sounds about right (just too hot for no pulse).



the diamond wheel in harbor freight's chainsaw grinder refill kit works well for sharpening tungsten with an angle grinder (not my idea, I'll try to find credit, it was someone else on this board). I just clamp it in the vise on the welding table.

For some reason, on our inverters, whether its the cycling frequency or what, the 1/16 tungstens suffer badly at 60-70 amps. Pulsing or NOT 98 amps are too hot because it heats the tungsten, to that temp and cooks it. Transformer machines MAY be able to go higher, but SO many of the "canned" and "boxed" recommendations floating out there are for transformer welders.

[ogorir]

have you noticed any difference in maximum amperage range for the 1/16" tungstens on AC(typ. params, 80-ish balance, 120hz, no pulse) compared to straight DCEN? I remember being able to weld .063" 3003 with 1/16" with my dad's machine, so 75A on the dial, generally running about 60A after the puddle's going, without issues. I'm curious, as I like the pinpoint starting characteristics of the 1/16" tungsten. we used 3/32" exclusively for years until I started researching TIG consumables and technique, and with the square wave transformer machines it makes a huge difference in arc stability on low amperage stuff going down to the 1/16" tungstens.

my dad started using the 1/16" for everything, though, and started to run though them.

I've been toying around with dropping to .040 for repair work on rusted sections in mild steel, as I usually only put 30a on the dial for that. have you tried the .040" with the IGBT inverters, enough to say the amp range?



on another(related) note, I'm scared of trying anything smaller than the 3/32" scratch start on the I-MIG 200. I was having splitting issues running 80A 3/32" 1/5% lanth on mild steel after a while (10 minutes weld time, I'd guess. it might also be because of the starts, though).

[Wrenchtamer]

At my shop we have a precision tig 275 that I use everyday. The tungsten I use in it most of the time is probably the diameter in question. I have not mic'd it, but I was curious today and I held it up to a 1/16 piece of filler and I would say it is roughly half the diameter. Now this is a transformer based machine so this may not apply to our machines (I have not tried it in the 256) but I have been doing stainless headers with it for the last week and a half or so, and today I did a steel repair at 107 amps. That tungsten is awesome. It's a little tough to sharpen, you kind of just scrape it lightly on your abrasive of choice and it's ready. it's so slim that it doesnt really make as big of a difference if the point is not perfect. I had to weld from the inside of some 2.5 inch tube and it was nice for that. I think you can get a 3 pack from airgas if you want to try it, It is NO good for ac, tho.

[jtybt]

The 1/16 tungsten was some I got from Harbor freight. The SS tubing was .040 wall and the base plate I was welding to was 1/8". I ran out of the 1/16 so I used 3/32 to practice laying a bead on the edge if 1/8" plate. I just need more practice.

[jtybt]

While I was welding up some small washers to 1/8" TIG rod for making a TV antenna, I noticed the whole tungsten would have like a coating of an electrical arc...kinda the whole tungsten was sheathed in a glowing halo. Never noticed it before until welding at very low amps. There was a jet of 'flame'coming out of the ceramic cone, just like a jet engine. I've burned the tip of my glove from this flame before using higher amps but just thought it was some kind of erratic arc start. With low amps, the flame coming out of the cone is subdued and more visable as to what it's doing.

It was working fine with low amp starts and all of a sudden it wouldn't start without the flame blowing out of the cone. Punching the foot pedal stopped the flame and get the nice little ball of light at the tip of the tungsten.

What causes this???

[Wrenchtamer]

Sounds like the same problem, man. I can't think of any electrical issue what would be likely to do that. Were you outside? Sounds like your tungsten was contaminated, then you layed on the pedal and burned some of it off. When you are through running a bead your tungsten should be nice and shiny. If it is turning blue you have inadequate postflow and it was allowed to oxidize when it cooled. If it is black or the cup is yellow you have a shielding problem (gas blowing away, bad gas) or your tungsten or consumables contaminated. The grinder that I use for tungsten came with a polishing wheel on one side, it actually gives the tungsten a nice chem sharp type of edge but you have to hit it with some solvent and scotch brite it before use or you will get an effect similar to what you describe. Also try cleaning your filler.

[jtybt]

OK, Made a plexiglass surround for my small table and got a diamond barrel sander and more 1/16" thoriated tungsten. Practice welding .030" SS (304). Tig set at 60 amps with and without pulse. Casio conversion foot pedal works smooth.

Still getting an occasional erratic start at low amp. Still stomping the pedal and backing off will smooth out the start.

Is there a picture showing where and how to set the gap????

[parkour]

Not sure if the LX is the same as the EX (what I have) but you can look in the front grille and see the gap. Just hit the pedal with the HF on and where you see the blue spark is where the spark gap is at. You use a feeler gage, like for spark plugs, and set it to .030" or there abouts. Mark might chime in with an official gap number.

If you've not had the unit apart before; you start by taking the rear plastic cover off, then the green metal cover. The face does not come off easily and should not be moved without a strong need and extreme caution. You can also use some emery board to gently remove any oxidation from the electrodes before setting the gap. Be careful about the copper filings getting into the machine if you file on the electrodes. Probably follow the usual rule of not fixing what isn't broken and don't file on the electrodes unless there is an obvious need to do so. If doing so, maybe use a vacuum cleaner to collect the filings.