BigWheeze

Pure Argon or pure hulium only

Eville140

When you use lift arc...how do you stop the arc?

Thanks
Randy

BigWheeze

Scratch Start (Lift Arc) you simple drag your arc to the edge of the work piece and then pull it away to break your arc

sohcpwr

nah bro.. scratch start and lift arc are two totally different things. Kinda like harbor frieght and miller

BigWheeze

Hobart is harbor frieght and they use the name lift arc so does Miller

Actully Scratch Start is another term for Lift Arc. Lift Arc is used on machines that don't have high frequency. For example Squarewave and Syncrowave. The start frequency is 60hz. Thus making the current jump from the work piece to electrode. The waveform looks like this

If the machine has a polarity setting make sure to use these settings
DCEN(Direct Current Electrode Negative) it will be used on mild steel and stainless steel.
DCEP(Direct Current Electrode Positive) Titanium cant take the heat steel can.
AC(Alternating Current) Aluminium

Direct current flows from the negative to the positive. AC alternates from DCEN to DCEP at 60hz.
DCEN the weldment gets hotter than the tungsten. AC gets equaly as hot

sloppy post you get the point though

Eville140

Lift-arc and scratch-start are two different things. Scratch start it for machines that don't have high frequency. My Thermal Arc 185 has a Lift-Arc setting. Do don't have to scratch the material in hopes that it doesn't stick or get contaminated. When in the Lift Arc mode there is a tiny current going through the torch. Then you touch the work piece with the tungsten, you can hold it there pretty much as long as you like. When you lift the tungsten from the work piece after about a second or so the high frequency kicks on and starts up the arc. Works great when I need to walk away from my pedal, but I just have not figured out how to kill the arc. Pulling it away form the work piece while cranking 140 or so amp is a bit freaky and leaves a nasty spark trail on the part.

Later
Randy

sohcpwr

i was wondering the same thing!! What ive been doing is cutting down the angle of the torch and holding it closer to the metal to get the pool really small, then pulling away somewhat abruptly. i know its not the best for the strength of the weld, but if i do it when its real hot- a large flame will blow in the direction of the arc

BigWheeze

Thanks jagojon3. I stray away from lift arc and scratch start. Welding transfer pipes you have to use a pedal. Cant have undercut (gouging) on the welds edge. Pipes run over 300psi.