Lift Arc TIG--crater fill?

[MQYJ]

I've been very comfortable with Lift-Arc for quite a while and through a LOT of practice I've been able to produce consistently "pretty" welds with the exception of the end of the weld.

Is there some trick to finishing the weld and breaking the arc without leaving an ugly crater at the end? I can do it no problem with a foot pedal but, I'm not running a foot pedal and don't intend too either as I really like the freedom to move around all over the table/shop without dragging the foot pedal around and then trying to keep myself in a position to run the pedal while welding out of position.

[blackdog220]

break the arc slooowly. It doesn't feel 'right' at first but will help eliminate the fisheye.

[MQYJ]

Do you continue to deposit filler as well or just finish th weld and draw the torch away slowly?

[jpmassey]

TIG with no foot pedal or finger trigger? How do you start/stop the arc?

[blackdog220]

Well...That's something you just have to develop a feel for.

After a certain point the weld will cool to where adding wire becomes impossible.
Is the problem just a small fisheye in the weld, or is there actually a big crater at the end?
If it's just a little dot then adding filler is probably not the issue. It sounds like your comfortable enough with the process that you should be able to get a handle on how much wire to add as you tail off with some practice.

jpmassey: you actually touch the tungsten to the workpiece and then lift to establish the arc, break the arc by moving the torch away from the work. Used when high frequency is not an option or available.

[MQYJ]

Originally Posted by blackdog220

Is the problem just a small fisheye in the weld, or is there actually a big crater at the end?

If it's just a little dot then adding filler is probably not the issue. It sounds like your comfortable enough with the process that you should be able to get a handle on how much wire to add as you tail off with some practice.

jpmassey: you actually touch the tungsten to the workpiece and then lift to establish the arc, break the arc by moving the torch away from the work. Used when high frequency is not an option or available.

It is usually a small dot rather than a large crater. Ultimately the goal is to be able to weld around a connection and tie the end of the weld into the start without it really being an obvious transition. I think I generally pull away much to quickly to break the arc for fear of the arc jumping to an adjacent surface and creating another little arc burn mark that I then have to deal with as well. FWIW, this is primarily on artistic and ornamental type pieces and parts but I'd like to get this figured out so it isn't an issue on other types of work where those things are more critical.

I'll experiment with drawing away slower even though like you said, it just doesn't feel "right".

Thanks

[blackdog220]

Something else you can try is to 'stir' the weld as you tail off. The idea being that you keep the puddle fluid and in motion while not actually making forward progress.
Just out of curiosity, what kind of rig are you using? What type of material?

[BumpyDodge]

One last fill dip and whip off the torch as quickly as possible (not slow) is how they taught me to do it in school. Pipe is a different animal, so YMMV.

If you really hate a finger amptrol that much, you can use just a contactor button with a sequencer. Most of the upper-end inverter based machines have programmmable logic just for this situation.

[MQYJ]

Originally Posted by blackdog220

Something else you can try is to 'stir' the weld as you tail off. The idea being that you keep the puddle fluid and in motion while not actually making forward progress.
Just out of curiosity, what kind of rig are you using? What type of material?

I'll give that a try as well.

I'm using an XMT 304. I'm mostly welding mild steel but I do get into a bit of Stainless here and there and use some silicon bronze filler on a most of the cast iron parts.

Originally Posted by BumpyDodge

One last fill dip and whip off the torch as quickly as possible (not slow) is how they taught me to do it in school. Pipe is a different animal, so YMMV.

If you really hate a finger amptrol that much, you can use just a contactor button with a sequencer. Most of the upper-end inverter based machines have programmmable logic just for this situation.

I've not ever used a finger amptrol before so I can't really say how I feel about them. They've always seemed like they would be a bit clumsy though. While my machine is an inverter it isn't as high tech logic as any of the newer rigs and doesn't have HF so I'll still have to touch down to start the arc, but that may be a good option to taper off my heat at the end. And your method is how I've been attempting to this point but I can for sure say I haven't done it right or least not on a consistent enough basis to recognize what exactly I did correctly.

[MQYJ]

Oh yeah, I have a gate and hinge brackets to weld up this weekend so I'll try to incorporate all of the methods you guys suggested and hopefully have something I won't be ashamed to post. I have some common fisheyes/craters from previous jobs so if I get it figured out I'll def. put up some before and afters.

[mudskipper4x4]

Originally Posted by jpmassey

TIG with no foot pedal or finger trigger? How do you start/stop the arc?

You sir, have never used a scratch start tig set up. Thats how real men do it.

[MQYJ]

Originally Posted by mudskipper4x4

You sir, have never used a scratch start tig set up. Thats how real men do it.

I was a clumsy tard the first time I used a pedal.

[sn0border88]

Breaking the arc off quickly is the right way to do it, slowy will lead to nothing but erattic ar marks and probably wont help much with the crater.

Honestly its part of the process, you can try and add some filler right as you break it off but its still the same idea. Break it off fast and purposefully so you dont get any stray arcs.

[blackdog220]

Originally Posted by sn0border88

Honestly its part of the process

Agreed. It's one of the drawbacks of scratch start. While there are things you can do to reduce the fisheye, your never really going to be able to totally eliminate it. I also find the thumbwheel controls clumsy, but the slide types are a little more manageable. Or poney up $800 for a wireless footpedal.

[MQYJ]

Originally Posted by blackdog220

Agreed. It's one of the drawbacks of scratch start. While there are things you can do to reduce the fisheye, your never really going to be able to totally eliminate it. I also find the thumbwheel controls clumsy, but the slide types are a little more manageable. Or poney up $800 for a wireless footpedal.

I looked at those already and they are They are compatible with my machine too.

Right now I'm holding out for a large job that I've been in talks about for a few months. My plan is to roll a Dynasty 350 runner package with the wireless pedal into that job and then my problems will all be solved. But there's no guarantee on that job going through so I'm coping with what I have for now.

[BumpyDodge]

There's a lot of misinformation in this thread. scratch start and Lift-arc are not the same thing. Lift-arc is a brand name for Miller's non-HF start electronics.

Non HF start methods:
Old school tig rig - scratch start (no electronic assist, scratch and go)
Newer Miller - Lift arc
Newer Lincoln - Touch start

Scratch start sucks, so few people still use it. The 2 latter terms are newer tech for situations where an HF start is not desired however, they are not just different brand names for the same thing - they actually work differently. Miller and Lincoln machines require a different techniques. Lincoln's touch start is closer to old style scratch start, but it doesn't stick/contaminate because there's a built-in delay. If you try to run Miller's lift arc like a scratch start rig, you're just about guaranteed to fuck up your starts. If you want to know more about Miller's Lift-arc, head over to their site and RTFM. You are supposed to pause for a second before lifting, not just scratch the tungsten.

Anyway the OP wanted to know how to break an arc, not start one so all this shit doesn't really matter. I just wanted to clarify it for the people who have not used newer non-HF start technology. Sorry for the Hijack.

[BumpyDodge]

Back on topic... MQYJ, does your end crater look like this? (Shadowing in pic makes it look worse than it is.)

[Cork]

Originally Posted by BumpyDodge

Back on topic... MQYJ, does your end crater look like this? (Shadowing in pic makes it look worse than it is.)

Simple fix for that is to crater out on the bevel?

[MQYJ]

Originally Posted by BumpyDodge

Back on topic... MQYJ, does your end crater look like this? (Shadowing in pic makes it look worse than it is.)

The pic is a tad fuzzy but from what I can tell and based on the poor quality pictures I've taken of mine in the past I would have to say yes, it is very close. I would probably agree with you Cork on the fix although like I said earlier, a lot of my stuff is cosmetic/art type stuff. Now most people other than weldors wouldn't ever notice such a thing but it's my work so it does bother me sometimes.



No worries on the hijack, that's really good info. My lift arc and scratch start settings on my xmt behave almost identical. At least close enough that I can't really tell the difference. I know there is something jacked up in the main board on my machine because I have no output display when sitting idle in the lift arc mode. It seems to weld fine although I suspect that there is excessive sensing voltage at the electrode because starting can be pretty harsh sometimes if I don't really dive in and make contact like I mean it.

[BumpyDodge]

That weld was done with XMT 304 and the weld did have a small crater, so I figured it might be worth comparison. Try a quick flick back over your last 1/4" or so of travel (where the bead's still red hot, to avoid arc strike/ micro crack defects). Everybody ties off a little differently, but that works in my experience. I only have to worry about a "perfect" tie off on a cap. Unfortunately I don't have any pics of a cap. Just trying to get an idea of how bad of a crater you're getting.

To start a Miller XMT w/Lift arc, you should just touch the tungsten directly down where you want to start, pause a brief moment and then lift *straight* up. The machine shouldn't do anything until you actually lift off the workpiece- it's OK to pause a second to get your filler rod in position if you need to. With a Lincoln's Touch start it usually works better to give the tungsten a really quick sideways tap - almost like striking a match. One's not necessarily better than the other, they just behave a little differently on starts. Just be aware you sometimes have to tailor your method to suit the actual welder that you are using at the time.

[MQYJ]

I'll try to remember to post a picture of it when I get back in the house. Pics are on the other computer.

I didn't realize how screwed up my lift-arc function was until I ran a different machine for a while at a buddy's shop. If I hover around the start point and don't contact down my welder will suddenly arc across the gap. It's a bit of a bitch at times but I've adapted to welding with it like it is. At this point I'm just trying to ride it out and avoid the $1k repair bill to replace the main board and bury the cost of a new welder in a job.

[MQYJ]

Here is a fairly normal instance. This is a 1/2" stainless hinge pin welded to mild steel cap rail. I wire brushed it after welding. Please disregard the weld appearance, not one of my better efforts. Kinda rushed through it.