[JFF45]

I have a cheap $798 (AUD) AC/DC 200 amp machine but it does have HF start. I often have an issue where the arc will not start unless i first (before hitting the pedal) lightly rub the tungsten tip on the alu surface. I don't mean scratch it, just lightly touch the surface as if it just needs to remove some fine film from the tip.
This can happen even after brushing the surface with the wire brush.
It never happens if I've just ground the tungsten or if the tungsten is still quite hot from just running a bead.
Touching the tungsten lightly to the surface like this never causes any contamination.

I'm assuming a very light coat of oxidation or something on the tungsten although I have a 6 second post flow.
Thanks!

[Olivero]

Yeah, as long as your HF does fire, I would assume its just oxidation.

I have the same thing occasionally but after a while, I just got used to it.

If you TIG steel, does it do the same thing?

[Jim FLinchbaugh]

I have an AHP 200X that did the same thing.
Adjusting the high freq point gap and aligning them, fixed this issue

[C. Livingstone]

Yeah,

I get that sometimes too, but mostly just with AC TIG, if I'm recalling correctly.

But I think I heard somewhere that the negating of that by the quick touch down to the base metal, isn't for breaking through some oxidation at the tungsten so much, as that it discharges any slight residual current that may somehow develop at the tunsten, so that the HF circuitry then senses it's OK to initiate a HF arc start again.

I'm still fairly new to AC TIG welding, and maybe I'm just hallucinating, but I do notice some slight static-like discharge at the tungsten whenever the HF starts need a little help that way.

My 2015 unit doesn't have HF gap settings, I believe, but Everlast did later go back to a HF gap-type daughterboard on my same model, I believe. So, maybe the lower-tech gap-type arrangement is better somehow.

Otherwise, I'll keep about a half-a-second of pre-flow and at least 5 seconds of post-flow for most things, which keep my tungsten color pretty nice. I'll be trying some new stuff soon though, which is reportedly an outstanding tungsten blend that makes arc starting better and can even reduce Argon consumption. So, we'll see about that!

Tri-Mix.jpg (40.79 KiB) Viewed 996 times

[JFF45]

Thanks for the replies.
I've read suggestions that later, even chinese, inverter AC/DC machines don't use gapped points anymore but I'll need to confirm that.

I've seen the static electricity theory mentioned several times and I'm apparently not alone in simply touching the tip to the workpiece. Some even seem to do it anyway as part of there normal startup process to eliminate the 'hit or miss' aspect of it.

I'm happy to keep doing it, might even do it every time, now that I'm sure it's not an impending fault in the machine.

Btw, it happens with both zirconiated and lanthanated electrodes.

[MarkL]

I'm happy to keep doing it, might even do it every time, now that I'm sure it's not an impending fault in the machine.

I've trained myself to lightly touch the tungsten to the work to make sure I didn't forget to tighten the collet. That also gives me added confidence that I know how far I am from the work when I start the arc. Both issues are related to getting older, the first has to do with the brain not always working, the second with the eyes not always working.

[JFF45]

I'm happy to keep doing it, might even do it every time, now that I'm sure it's not an impending fault in the machine.

I've trained myself to lightly touch the tungsten to the work to make sure I didn't forget to tighten the collet. That also gives me added confidence that I know how far I am from the work when I start the arc. Both issues are related to getting older, the first has to do with the brain not always working, the second with the eyes not always working.

I can relate.. Starting to learn TIG at 71 might have some asking questions about my brain but the eyes are still coping at this stage.

[Jim FLinchbaugh]

Thanks for the replies.
I've read suggestions that later, even chinese, inverter AC/DC machines don't use gapped points anymore but I'll need to confirm that.

mine's 2016 model has point gaps. How hard is it to look?
Struggle on

[JFF45]

Thanks for the replies.
I've read suggestions that later, even chinese, inverter AC/DC machines don't use gapped points anymore but I'll need to confirm that.

mine's 2016 model has point gaps. How hard is it to look?
Struggle on

Lucky you!
I really don't see the point in opening a new machine that has no issues..

Who's struggling?

[electrode]

Also check your work clamp for a good connection or your welding table for same. If my table gets a bit rusty mine will do that sometimes but it's rare because I try to keep it cleaned up.

[JFF45]

Also check your work clamp for a good connection or your welding table for same. If my table gets a bit rusty mine will do that sometimes but it's rare because I try to keep it cleaned up.

I got into the habit of using a heavy 3rd hand I made with a MIG copper tip fitted to it that I place on the workpiece. It's connected to the machine with an auto earth cable via the machines clamp.
Sometimes I forget to place it on the piece and the arc starts the same anyway.
I've found the MIG needs a much better earth but probably because of the current difference.