Tig Welding Questions

[kf4zht]

Getting used to this whole TIG with a foot pedal and HF Start thing. Welding last night and had a couple questions issues that I could use some help on

Machine - Miller 330 a/bp - Set to the 20-250 setting at ~60 power, HF start, Argon at 20 CFH
1/16 red tungsten in a CK Gassaver with pyrex cup
3/32 filler (er70s iirc)
Material - 1/8 HR .5x.5 angle, **** welded corners. Wire wheeled to get the scale off and wiped down

Issue 1 - This was about 8 welds in - Started getting porosity and spatter, when I cut the weld off there was brown soot on the sides of the weld. Looked over to check if the reg was flowing and it was during post flow. Went on to the next joint and didn't have any issues with that one. Some kind of contamination?

Issue 2 - HF Start - How should this work? Sometime I have to get within a 1/16 of a inch and wait for a minute for the arc to start, other times I am 1/4 inch away and it fires up right away. Is this normal or do I need to adjust something (Looks like I have a HF intensity dial and the spark gap).

 

[raceman17]

Turn your argon down to 12-15 Cfm. Check for leaks in your gas line and tig torch. Sounds like a leak somewhere.

your hf should automatically jump a gap and start your arc. If you tungsten is contaminated you may have to scratch it against the steel to get it to fire off. You can try to increase your hf intensity or look at how much gap you have in your spark gap. You may need to take those out and clean them and readjust them. The manual should give you the recommendations.

 

[king nero]

Sometime I have to get within a 1/16 of a inch and wait for a minute for the arc to start

This is surely not right.

Either your tungsten is massively contaminated, or your machine is defect.

As for the spatter and such, wire wheeling won't completely remove the mill scale in most instances. Instead, use either a deburring disc or a course flap wheel.

 

[that-guy]

how are you grinding your tungsten? red isn't a very desirable electrode either, E3's give good results, as do the light blue (2% lanthanated) which is what I use. as said by others, check for leaks for turn the gas down

 

[dr_clyde]

Thoriated tungsten is fine for steel. Your HF probably needs adjusting. I would prep HR steel with a grinder though, the mill scale don't come off with a wire wheel and could be causing your problems. Have you tried it on shiney clean steel?

 

[zmotorsports]

Check what the previous guys mentioned first. I am generally in the 15-17 CFM on argon flow. Sometimes too much flow will cause some turbulence and actually induce oxygen into the molten puddle which is the exact scenario you are trying to prevent with the gas in the first place.

Metal needs to be CLEAN. No mill scale at all, the wire wheel won't remove it all. Flap disks work well and then a quick wipe with acetone.

Tungsten stickout is also critical as is torch angle, especially with a standard style of cup. If using a gas lense you can "fudge" or "cheat" a bit on stickout but torch angle should still be no more than about 15-20 degrees off vertical, leaning in direction of travel.

Stickout as a general rule of thumb is half the diameter of the cup, again you can cheat this a bit with a gas lense. Example, 1/2" cup should have no more than a 1/4" stickout. Also make sure you are using a large enough cut to begin with. Lack of gas coverage due to too small a cup and having too narrow of a gas stream is very common with new weldors. Tungsten grinding parallel with the tungsten is also critical to avoid arc scatter.

Also, post up some pics of your welds and maybe we can help with some additional information.

Mike.

 

[MoonRise]

+4 on a wire wheel not being adequate for mill scale removal.

You need to use a flap disk or an actual grinding disk to remove mill scale and get down to clean, shiny metal.

Wire wheel removes paint and loose rust, but doesn't do much to mill scale. Except sort of rub-off onto the mill scale and make it look sort-of shiny and thus you think you got down to clean shiny metal but you didn't.

 

[gtermini]

If it's an older welder, the trick for easy arc starts is to strike the arc on a small piece of copper right next to where you're gonna start your weld bead.

Greyson

 

[kf4zht]

+4 on a wire wheel not being adequate for mill scale removal.

You need to use a flap disk or an actual grinding disk to remove mill scale and get down to clean, shiny metal.

Wire wheel removes paint and loose rust, but doesn't do much to mill scale. Except sort of rub-off onto the mill scale and make it look sort-of shiny and thus you think you got down to clean shiny metal but you didn't.

Sounds like this is what may have happened, as several people said. It would also explain why I only saw the issue on 1 of the corners, despite the gas and stickout being the same.

Stickout was around 1/4-3/8 of an inch, using the small gas saver lens. Not sure of the number, but it is pictured here: http://www.ckworldwide.com/gas_saver.htm

I will play with the HF gap and setting to see if I can get more consistency. I just blew the machine out when I got it and started welding. Seemed to work ok on al, so I figured HF was fine.

I will get some pictures when I get home

 

[raceman17]

When I got my old Miller dialarc welder years ago I took it apart and blew the machine out. It took me a few days to realize that I blew a **** load of dust into the hf gap and I couldn't figure out why I had no hf. Go back and make sure u clean those point gaps good.

 

[MoonRise]

RTFM for the Miller about checking and setting the HF spark gap.

If you don't have the manual or haven't looked/downloaded one yet, go to the Miller website and do so. www.millerwelds.com

From the (a) manual on the 330A/BP,

It is necessary to readjust the spark gaps every three to four months or whenever intermittent operation occurs.

 

[Rawlins87]

+5 on wire wheel not getting mill scale off
+2 on setting gap for HF

 

[Zeke]

I believe you should turn down the flow using a gas lens. 20 seems high and it might be out of calibration. Got to go by feel sometimes.

 

[kazlx]

Yes, problem number 1 is definitely that a wire wheel won't remove scale. I would open the machine and clean and check the connections, HF included like mentioned.

Also, I usually bump the pedal away from the material to get the flow started and then use the tail of the post flow as a pre-flow...

 

[kf4zht]

Here is the joint with the issue:

Here is another in he same string that seemed fine:

Here is a tube joint where the weld went fine but has some brown around the outside of the haz. I am assuming this is ok:

I turned down the gas to around 12 and played with the HF intensity setting. I couldn't find my feeler gauges to check the spark gap, but I blew out the gaps of dust. There is a switch inside labeled "HF start" which goes between "in" and "out". Not sure what it does.

Sent from my SCH-I535 using Tapatalk

 

[dr_clyde]

That is definitely a symptom of a shielding problem. I would work my way back from the torch. Start with a ground shiney piece of steel. Then check torch connections. Back cap O-ring, gas to torch, ect. Keep doing this until you find the problem. Have gas flow set to 10-15 CFH. Too much gas can pull in atmosphere. Make sure there isn't a breeze.

 

[welder4956]

Congrats on your new (to you) machine. This is a very good and reliable machine.

The spark gap needs to be set at around 0.010" for normal use. If you notice it interfering with electronic equipment in the house, the gap can be reduced to as low as 0.004".

The HF switch should have 3 positions: Start, Off, and Continuous. The center position is Off and is for stick welding. Start is up and is used for for DC TIG, Continuous is down and is used for AC TIG.

There should also be a HF Intensity dial under the front cover where the leads attach. Raise the front door and look for a black knob. Rotate the dial to increase or decrease HF intensity.

 

[A_Pmech]

Where were you doing the work? Did you have a fan on or the doors open?

 

[zkling]

Grab a clean piece of steel, a freshly ground tungsten, strike an arc, form a pedal and stop the arc. Allow it to post flow and then examine the puddled area as well as the tungsten. That should show whether you have a user issue while doing joints or a issue with the machine supplying a pure inert coverage.

Future reference, I prefer to vacuum out a machine or use a leaf blower. Sometimes with a blowgun or compressed air you can make matters worse by blowing junk further into where it doesn't belong. What do the faces of the spark gap electrodes look like? Smooth? You can use a clean sheet of paper to clean them off and then a quick wipe of alcohol. Set the intensity to ~50% of dial. It should easily jump a 1/16" gap. If you hold the torch away from the ground and floor the pedal do you hear the HF gaps buzzing?

 

[JDon99]

How much Argon is left in the tank? I had a similar problem a few years ago and my tank was getting low but still plenty of pressure and would run in and out of having a decent shield. Swapped tanks-no more issues.

 

[lametec]

I have an Airco version of the 330a/bp, and my HF is about like yours.

When the tungsten is warm from just having welded, the HF will easily jump a 1/4" gap. When cold, it might take a lift start to get it going.

I've replaced the two black HF capacitors and the points. Spark gap is adjusted according to the manual.

 

[kf4zht]

Grab a clean piece of steel, a freshly ground tungsten, strike an arc, form a pedal and stop the arc. Allow it to post flow and then examine the puddled area as well as the tungsten. That should show whether you have a user issue while doing joints or a issue with the machine supplying a pure inert coverage.

Future reference, I prefer to vacuum out a machine or use a leaf blower. Sometimes with a blowgun or compressed air you can make matters worse by blowing junk further into where it doesn't belong. What do the faces of the spark gap electrodes look like? Smooth? You can use a clean sheet of paper to clean them off and then a quick wipe of alcohol. Set the intensity to ~50% of dial. It should easily jump a 1/16" gap. If you hold the torch away from the ground and floor the pedal do you hear the HF gaps buzzing?

I will test with just a spot and see how that does. Not sure how the faces look, when I couldn't find my feelers I didnt want to move them until I have a way to measure in hand. Can hear much over the tig cooler running. Will try shutting the cooler off and hitting the pedal to listen. As long as I never strike the arc it shouldn't fry anything

Where were you doing the work? Did you have a fan on or the doors open?

In a closed in shop, doors closed, no AC vents. Only thing that could generate a breeze is the fan on the welder. I should be able to direct that away with a piece of cardboard.

Congrats on your new (to you) machine. This is a very good and reliable machine.

The spark gap needs to be set at around 0.010" for normal use. If you notice it interfering with electronic equipment in the house, the gap can be reduced to as low as 0.004".

The HF switch should have 3 positions: Start, Off, and Continuous. The center position is Off and is for stick welding. Start is up and is used for for DC TIG, Continuous is down and is used for AC TIG.

There should also be a HF Intensity dial under the front cover where the leads attach. Raise the front door and look for a black knob. Rotate the dial to increase or decrease HF intensity.

Yeah, I found a piece of shim that measured at .015, and it wouldnt fit in the gap, but that was as far as I got. Need to check the faces as indicated above.

The HF switch is set to start, not sure what the intensity is set to due to a loose knob. I can feel it move up and down but there is play before it turns so reference is moot.

I did reread the manual. The start circuit in/out switch determines if it uses the start current setting or just the foot pedal. Also found that the manual refernce for the balance switch is wrong. It says up for SMAW and down for GTAW, however some machines have the switch flipped. Really it is closed for SMAW, open for GTAW.