[Tommy812]

I'm very new to tig. With that said I'm trying to tack weld 1/16 mild steel at 50 amps. The metal blows away a few seconds once I initiate the arc. Please help.

[dirtmidget33]

Are you using a pedal?
Does machine have a hot start?
-If so what is it set at?
Arc length is it to long? Causing excessive heat.
What is your gas flow set at?
what size tungsten?
What machine?

Check hot start setting first and set low. I know more questions than answers but can help us narrow down the issue.

[TRACKRANGER]

Definitely try holding a tighter (smaller) arc and see if that changes the situation. Presumably this is a butt weld? Do you have a backing plate? Do you have a gap between the plates (e.g. 1/16" or similar).

Start with a tighter arc and see if you can also increase travel speed.

[Tommy812]

I don't have hot start. I'm using a pedal. I have no backing plate. It is a butt weld.

[TRACKRANGER]

I don't have hot start. I'm using a pedal. I have no backing plate. It is a butt weld.

And what happened when you decreased arc length (tighter arc), and increased welding speed? Any results change?

[WJH]

If his welder is an inverter, won't a tighter arc = hotter? The opposite of a transformer welder?

[MinnesotaDave]

If his welder is an inverter, won't a tighter arc = hotter? The opposite of a transformer welder?

I believe you are thinking about welding in stick mode - the dig function (or arc force) function is not used in tig mode.

When I scratch start tig in stick mode, I turn the feature off or put it on it's lowest setting.

I know it sounds weird to scratch start tig with an inverter that has a tig function - but my invertec v250-s requires a hand control when not using the foot control. I only own the foot control - so flipping it back to stick solves the problem.

[MinnesotaDave]

I'm very new to tig. With that said I'm trying to tack weld 1/16 mild steel at 50 amps. The metal blows away a few seconds once I initiate the arc. Please help.

It should not take a few seconds to tack 1/16" material - if you take too long the metal can over heat and blow away.

Get that rod in there a little faster and join them up - make sure there is no gap - the thinner the metal, the more important to have excellent fit up.

Or, "speed tack" them with just a quick burst of amps (just a split second).

Btw, new people to tig should learn the basics with 1/8" steel in my opinion - less stuff to go wrong gives a less frustrating learning curve - do the thin stuff after the basics are mastered (in my opinion).

Good luck and post pics

[dirtmidget33]

If his welder is an inverter, won't a tighter arc = hotter? The opposite of a transformer welder?

NO a shorter arc length will not make It hotter. TIG machines are constant current, so when you leave pedal in same spot and change arc length with both Transformer and inverter TIG machines the amperage remains constant but as arc length is increased the voltage increases, smaller arc length less voltage amperage remains the same.

Here is Lincoln link that might help you understand it also

http://www.lincolnelectric.com/en-us/su ... utput.aspx

[zank]

When tacking, remember that the molten metal wants to go towards the heat. So if you try to start soft and "sneak up" on a puddle, you will heat the surrounding metal quite a bit. The puddle will then want to pull away from the edge toward the bulk of the metal and you end up with a hole. It take some confidence to strike the arc and puddle it fast, especially on thinner materials. But that is the key. Strike, puddle fast, and move the puddle to the adjoining part. Torch angle can also help. You can use the arc force a bit to push the puddle to the adjoining part. But again, the worst thing you can do is strike a low arc, camp out because you are nervous about blowing a hole, and then blow a hole.

[Cricket]

NO a shorter arc length will not make It hotter

I thought that you can "concentrate" or "fan" the heat (given that the current stays the same) by changing the distance in certain limits.
Maybe I am wrong

[zank]

If you make the arc longer, you increase the voltage (and the width of the arc cone). And since current is constant, an increased voltage means more power (watts) going into the part. So more energy spread over a larger area.

[Cricket]

If you make the arc longer, you increase the voltage (and the width of the arc cone). And since current is constant, an increased voltage means more power (watts) going into the part. So more energy spread over a larger area.

Ok, so the "energy/heat density" stays about the same? Makes sense!

[MinnesotaDave]

If his welder is an inverter, won't a tighter arc = hotter? The opposite of a transformer welder?

NO a shorter arc length will not make It hotter. TIG machines are constant current, so when you leave pedal in same spot and change arc length with both Transformer and inverter TIG machines the amperage remains constant but as arc length is increased the voltage increases, smaller arc length less voltage amperage remains the same.

Here is Lincoln link that might help you understand it also

http://www.lincolnelectric.com/en-us/su ... utput.aspx

Remember the phrase "relatively constant."
No machine holds stuff right on the money - the amps change a little.

And when stick welding, the amps can change quite a bit - especially on an old transformer machine, or an inverter with "dig" or "arc force" functions.

[Captainbeaky]

I'm very new to TIG as well - I'm following advice here.

Practice....

So this is exactly what I've been doing.

One of the bits of practice I have been doing with my TIG is to practice doing a small tack - basically bringing a small area up to puddle temp, and then stopping. Getting the hang of the arc, and how the heat builds.

I imagine that It's a bit harder with my scratch start than hf start - I've not got a pedal either, so I can really get the heat buildup out of hand!

I spent over an hour burning holes in a bit of 1mm steel just to get the hang of putting a small tack weld without blowing it's brains out.

I played around with the current to see how it worked - and the arc length - to find the sweet spot that wouldn't blow holes, but wouldn't take too long to puddle.

It does take a bit of time to get the hang of - especially if, like me, you are used to The MIG way of welding.

I have to admit - I found it great fun closing up all the holes that I blew in the steel - turn the current down a bit, then just follow the bead around and around the hole... Very therapueutic in an engineer kind of way.

keep practicing.