TIG scratch start finish technique?

[jumper]

Well I've finally got a tank of argon to go along with my ebay tig torch and regulator and have practiced a few beads. Seems to be going ok but I'm having trouble finishing the bead. I always have a "blowout" on the last part of the bead. Looks ok when I pull away the torch but it always seems to bubble up and leave a hole.

Just wondering how other buzz box tiggers finish their beads so they look nice...

thanks,
Frank

[Pangea]

You don't have a foot pedal?

[~Point79~]

yea if you have a pedel you just back off the heat slowly
if your scratching then try finishing your bead by draging the heat away from the stop point as much as possable to stop geting the pinhole your talking about

[jumper]

I'm using an old Miller ac/dc stick welder. No foot pedal.

[Pangea]

No pedal, reverse direction and break the arc over a short distance.

[jumper]

Thanks for the tip. As soon as it's a little warmer than -20 degrees I'll get out to the garage and give that a try. As soon as I produce some welds that don't look like snot I'll post some pics.

thanks,
Frank

[j.w.]

85 in texas

[gt403cyl]

I know exactly what your talking about jumper, I'm in Oshawa, 45min east of Toronto. It's still nasty weather here too, currently -14C here (1:30pm Sat.) I really don't like working outside, or even in my unheated garage in this weather. Anyway, I will have to try the tip for ending the beads with my scratch, always up for tips & tricks...
Jeff

[partagas]

I have the Harbot Frieght scratch start tig welder. I was wondering if their was a way to add or build a pedal for it??????????????????

[jumper]

GT... I'm in Ottawa. I think it's about -18 right now. Not much fun. We've had it ok for the most part. Fairly mild.

Partagas.. try searching for homemade tig pedal. I know someone posted plans or a how-to a while ago. IIRC, you plug the pedal into the outlet then plug the welder into the pedal. Only problem might be the cooling fan motor cutting out.

[jumper]

It finally got a bit warmer (-10ish) so I was out in the garage practicing today... Comments are welcome.

First pic is a mess. Didn't clean the metal and dipped the tungsten in the pool at least once. The yellow circle is the end of a weld where i just pulled up the torch quickly. The red circle is a bubble which, I'm assuming, comes from the metal or tungsten being dirty. Correct me if I'm wrong..

Second pic is the same tubing but I ran a flap disk over it quickly and also had a freshly ground tungsten. Makes all the difference. No bubbles. Also the green circle is Pangea's suggestion for the "no foot pedal" finish, ie, reverse direction and break the arc quickly. Works like a charm. Thanks.

Third pic is is an edge joint on some reasonably clean material. 1. Bead started ok. 2. Dipped the tungsten in the pool (or possibly touched the filler to it) and had to regrind. 3. Bead restarted with clean tungsten. 4. I ran a bead with no filler.

Fourth pic is some 12 or 14 ga stainless. Top bead went ok but the finish left a pinhole (just pulled up the torch quickly). Middle bead went well including the "reverse direction" finish. Bottom bead is not wirebrushed. Not sure if that's the right colouring for a stainless tig bead but the first part looks ok. I think I started falling through at the end so I made a mad dash to fill it in and do the reverse direction thing.

What I've learned so far:

- steel must be clean, clean, clean. Otherwise the puddle bubbles. This is probably why I had much better luck with SS. It's already free of rust and scale.

- the first hint of a blue or discoloured arc and it's time to regind the tungsten.

- not having a foot pedal is somewhat of a pain. It's harder to control falling through and finishing a bead nicely required some doing. Not impossible though. Reversing the direction works really well. Seems to promote a more gradual cooling.

- keep several ground tungstens handy.

[partagas]

GT... I'm in Ottawa. I think it's about -18 right now. Not much fun. We've had it ok for the most part. Fairly mild.

Partagas.. try searching for homemade tig pedal. I know someone posted plans or a how-to a while ago. IIRC, you plug the pedal into the outlet then plug the welder into the pedal. Only problem might be the cooling fan motor cutting out.

I found the thread. But I do not have the skills to build it. I would buy it before killing myself trying to make one.

[jumper]

Too hot? Really? The first picture I can understand but I didn't think the others were too hot. The steel is .100" and the stainless is about the same. I was using two different tungstens. One was 3/32" 2% thoriated ground to a point with a tiny flat. The other was a 1/16" 1.5% lanthanated ground the same way. Filler was 1/16" because that's all have. All DCEN running about 60A. Hard to tell exactly how many amps because I'm using the buzz box's dial which isn't very accurate.

The third pic in section 4 is where I used no filler. And no, there's no pulsing. I'm using a AC/DC stick welder with a tig torch and bottle of argon. Scratch start only. If I ever have a spare 2k burning a hole in my pocket I'll consider buying a more modern tig setup. Until then I'm making due...

thanks for the comments.

[ondarock]

GT... I'm in Ottawa. I think it's about -18 right now. Not much fun. We've had it ok for the most part. Fairly mild.

Cool...finally someone else in Ottawa....well I'm in Metcalfe actually...south east end suburb

We've had a mild winter, but the mild days followed by freezing rain evenings and snowy nights are no fun.

[IndianOutlaw]

To save your tungsten (abit) before you dip the tugsten in the wire or the piece you are welding( LOL , just kidding), Try and hold the torch close to the plate (about 1/8" off from tip of tungsten to the metal) and use your filler wire to initiate the arc by striking it (like a match) between the tungsten and the work. Once you have the arc started, you can bring your wire around to lay down a bead. This may take some practice, but it's what we do all the time on x-ray pipe welds using GTAW.
Also, when you are ready to break the arc, you can place the filler rod to the side of your weld and run the arc on the rod and then pull the rod off the work. You need to be quick (if you are running hot, cause you'll likely melt the rod if you linger too long. Also be careful if you are welding stainless as you need to keep the argon on the bead (you just made) so you don't contaminate the metal. I really prefer to have a rheostat whether it's a foot pedal or a hand-held unit, but I work construction and sometimes you are lucky if you get a welding machine that stays at a constant setting, so you have to learn to adapt.
Your welds will get better with time.