hifg freq. start problem?

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I am selling an aircoheliarc IV and the other day a guy came to try it out. He brought someone with him who knows how to tig well so he knew itworked correctly. the problem was when he tried to ac tig the onlygas I have is steel mix for my mig welder, so needless to say, that did`nt work out too well. Once he got around to trying to dc tigat around 80 amps with a 1/8" electrode, the high freq. would`nt start until the electrode was around 1/16 or 1/8" from the work. I thought this was normal, but he said it should start an arcat about 3/4" or so. Is this true, as I don`t want to sellsomething that is`nt working correctly. any help would be appreciated.
Reply:I'm pretty sure the HF on my HTP TIG with a 1/8 electrode will not start and hold an arc at 3/4 inches from the work surface, and I know it will not weld at that distance.  I'd say mine will do it at 3/8 inch.  You are probably onto the problem - not using pure argon.  If the gas you used has a higher ionization potential than pure argon, you'd have to get closer for the HF to start an arc.  Get some pure argon or helium and try it again.TeddCoHTP Microcut 400 & Invertig 160DC  Smith Dual Guard MD-510 OA Rig  Lincoln SP135+  Hobart Stickmate LX 235/160
Reply:ok will do. Botttle is almost empty anyway, and I`m pretty sure I can still mig with argon so it won`t get wasted. thanx for the reply.
Reply:Doesnt pure argon make your mig run too hot?
Reply:Aluminum run with a MIG unit needs pure Argon, but steel won't wet out to the edges well with it and needs a slight amount of oxidizing gas in the mix, usually 98%/2%O2  or /5% CO2, down to 75 /25 CO2 for 70s-6 wire.BTW, isn't this the second post of this same question?
Reply:Yes, I wasn`t sure where to post so I put it in general and then noticed the other forum, where I figured it would be more suitable. As for the argon I guess I`ll scrap that idea and just refill the bottle I have with steel mix. I`ll have to get a small bottle for now of argon. Thank you all for the input, it`s been alot of help.
Reply:Originally Posted by WelderskelterDoesnt pure argon make your mig run too hot?
Reply:My invertec 205 will strike an arc from 2ft away...if I am wet, and leaning on the ground lead when I accidentally step the pedal!! Other than that, it strikes an arc from about 1/8" to 3/16". With an arc running on fairly high amps, I can stretch the arc to maybe 1/2 inch or more, but I can NOT start one from 1/4" under normal circumstances.And then, after so much work...... you have it in your hand, and you look over to your side...... and the runner has run off. Leaving you holding the prize, wondering when the runner will return.
Reply:Forget the helium. It is for welding on very thick aluminum weldments to increase the penetration.The high freq is initiated by large capacitors and capacitors can only absorb a certain amount measured in microfarads. Then they need replacement. Many times the capacitor is marked with the max amount, Do not work on it if you are not qualified, You could get zapped.Make sure your welding cable connections are tight. They will loosen from AC vibration over time. A visual inspection is not good enough. You need to actually give them a slight tug and see if they are tight. Sometimes they look good but when you give them a pull the wires come right out of the socket because the allen screws have loosened.Last edited by Donald Branscom; 11-02-2008 at 12:41 PM.AWS certified welding inspectorAWS certified welder
Reply:thanx for the tips,I`ll make sure and check the connections. I`m glad to hear that it`s probobly just a gas issue, but I was going to go ahead and check the gap on the contacts but can`t find any info on the measurment. does anyone know how to get the info. It seams to have carbide instead of copper contacts like an old lincoln idealarc. They seemed to be dirty and the wear marks are to one side of them but they are not rounded off at all. I went ahead and cleaned them and put them back to the same distance. Again thanx for all the info.