DocRob
DocRob Reader
5/9/23 4:44 p.m.

The proliferation of Lift Start or 'Scratch Start' TIG welders makes it cheaper than ever to start TIG welding. But the downside of these inexpensive boxes is that it is difficult to consistently strike an arc with a lift start TIG, which can make them frustrating to use. Also, they can leave nasty little score marks that mar your otherwise beautiful welds. Finally, a lot of people lift the electrode too fast to end the weld causing a blister of hot material and voids in the weld, because the gas goes away too quickly. 

I don't like any of those things, but my budget is tight, so I compromise, this little thing, is my "Scratch Start Helper". A piece of 1/16" thick copper, that I place at ~45 degree angle to my weld, I use the copper to strike my arc and then draw my arc back on that copper to let the puddle cool before killing the arc. I hold it in place with a steel binder clip and some good old fashioned magnets. 

You can use a copper spoon in the same way. I've just found the angle I can place flat plate to the work surface at makes for a nice clean transition.

Here I just stuck it onto the edge of the car where a Tonneau snap once was. Maybe I'd want to fill this hole (though obviously not with the current lack of prep to this surface) and I'd strike the arc, fill the hole, and cool the puddle, with the arc on the plate, before breaking the arc. 

Noddaz
Noddaz GRM+ Memberand PowerDork
5/9/23 5:59 p.m.

Interesting.  Show me more.

Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) GRM+ Memberand MegaDork
5/9/23 9:11 p.m.

Yes.  Do tell.  I own one of those do-it-all Arc/wire-feed/MIG/scratch-TIG machines and I've only ever used the MIG part.

DocRob
DocRob Reader
5/9/23 10:02 p.m.

I got the tip to avoid cratering originally from this Youtube Video: https://m.youtube.com/watch?v=28NRNYACv9I

The two challenges I was having was cratering with oxidation and balling the tip of my Tungsten up by not reliably getting my arc struck. 

Once I started playing around, I discovered that you can start the arc by having the tungsten on the edge of the copper and drag it towards your weld, basically as soon as it breaks the edge of the copper your tungsten tip strikes the weld material and the arc lights off in a tiny fraction of space. The ~45-degree angle helps you keep you aligned and get the right distance to keep the arc'ed tungsten from hitting the surface, meaning your scratch starts are more consistent.
 

If you place the copper right next to the weld area any "scorching" from striking the weld will be complete covered by your subsequent weld, but honestly with some practice and effort your scratches will be so small as to not be noticeable or an issue. 

californiamilleghia
californiamilleghia UberDork
5/10/23 11:03 a.m.

do you need to ground the copper plate ?

DocRob
DocRob Reader
5/10/23 1:17 p.m.

In reply to californiamilleghia :

I have not had to clamp the plate or spoon to the weld area with the ground clamp. Remember when TIG welding steel, you're running on DC polarity (torch is - and clamp is +). So technically the torch tip is creating the ground. I think this is why you don't have to 'ground' the plate or spoon. But I'm not really sure if that's why. 

ETA: IIRC and it's been awhile since I've tried it, clamping the plate did not cause me any problems that I recall either. So, while it isn't necessary, it also not a big deal if you clamp it. 

ETA 2: Now that I think about it, since copper is a great conductor and you stick it to the surface with magnets and a steel binder clip, and the edge of the copper is touching the 'grounded' steel, it probably ends up 'grounding' itself that way anyways. Which is probably why it doesn't matter. You'll see on my plate that the edges are brushed/sanded fairly clean, that does seem to help with more reliable arc striking and keeping the arc where you want it when you bring it up to let the weld puddle cool. 

DocRob
DocRob Reader
5/13/23 7:58 p.m.

Just to confirm for folks wondering. I had the box out this morning and was doing a bit of practice to dial in. Scratch Start helper in place, ground clamp on my steel, copper resting on the steel. 

Starting with torch in hand with tungsten above copper. I turn on the gas, then come down and when the tip hits the copper it will arc. But, because it's copper the Tungsten tip won't stick to it easily like it will steel.

So, make a little swoop scratching the Tungsten on the copper and then off the edge of the copper onto the steel and et voila! You have a scratch started TIG arc, without touching the tungsten to your steel. To finish, lay your bead, then draw the arc back over to the copper letting gas stay on over the puddle until it solidifies (5-count or so), and then whip the torch away to kill the arc.

Couple of other tips - thinner copper works great for getting the arc and getting the puddle cooled. But it heats up FAST. So don't grab that copper until it cools some. You will burn yourself right through thin TIG gloves...(don't ask me how I know). 

obsolete
obsolete GRM+ Memberand Dork
5/13/23 8:04 p.m.

Very cool. When I get my lift TIG machine set up I'm definitely going to play around with this.

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