arc starting problems

[dutchman]

Starting the arc has always been a bit problematic with my Lincoln Invertec HF-start welder. I used to blame my lack of skill, but am starting to doubt the machine. Is there any way to check?

 

[irondarren]

You mean you think you hf isnt working? On my inverter fusion if you hold it about 50mm from the work piece and try starting it, it jumps the gap but wont ignite an arc, but keeps arcing a fat spark acrossed the gap.
What i have found since adding a footpedal is if you just push the pedal down a slight amount it will arc, ignite and die, this is because i havent pushed the pedal down far enough and its try to maintain an arc on 10amps, which is to low for a 2.4mm tungsten.

 

[dutchman]

I have everything set up fine, proper contact etc, hold the tungsten about 1mm in a somewhat flat position above the work (tungsten is properly grinded to a point), set at 60Amps, press the button, and sometimes it strikes, but just as often it doesn't. No matter what I try
Usually I give up after meddling about and try my luck the next day. So yeah, I suspect the HF could be bust.

 

[dutchman]

I discovered that if I touch the work piece before pressing on the start button on the torch, a small spark jumps. Maybe it is the capacitors discharging, not sure. When I push the start button after that, the arc starts fine. Not sure how or why, but am happy it works

Thanks for your description Darren, it helped me search in the right direction.

 

[hotrodder]

Sounds like it could be 'tungsten frosting' but which model Invertec? The higher end machines have a hidden menu for some of the parameters and (on the 205-t at least) HF parameters are adjustable

Tungsten frosting... if it'll start a freshly ground tungsten but the tip sometimes/always need touching/scratching before it'll restart a used tungsten then it could be microscopic deposits on the tip. Increasing post flow time may fix it, some tungsten flavours seem more prone to this than others

 

[dutchman]

Looks like you are right on the tungsten freezing, Hotrodder.

The machine I use is a 12 year old Invertec v200t and I haven’t been able to discover a knobbie for adjusting on the HF settings on it. (She still welds quite nicely though for and old handbag welder )

So, next step was to try a freshly grinded tungsten of a different brand (2% ceriated) and starting goes much better now. I also checked the box of old tungstens to look for a brand name, but couldn't find any. I paid a stiff price for it (20 bucks), so I guess the hardware store didn’t do me a good deal and provided me some sub standard stuff that is quite prone to freezing.

Thanks for the hint.

 

[pedrobedro]

Earthing your workbench to something other than the welder helps I found.