About welding RF ignition arc-start

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graham-xrf

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A question about something that is the norm for TIG, but begs a whole lot of questions for one who does not know.
RF ignition, also called HF-START is the feature.
I am, of course, going to be trawling the subject until I wring out everything, but I thought to ask here first.

My welder, (yet to arrive), is basically a MIG welder that can be used in a variety of other welding methods, including one called "TIG-LIFT". I understand this means the TIG arc is started with a "scratch-lift" technique. Just thinking it through has me expecting the trick cannot be good for the tungsten point, nor for the control of the start, or re-start of a weld. I do understand the principle.

Q1. Is RF ignition a feature that could help start all the other weld methods as well? (I mean other than TIG)

Q2. Is RF start something that can be done with an add-on technology? Could one have it in/on a TIG torch, or spool gun?

Q3. Is there something fundamentally incompatible about MIG welder's current supply, making it unsuitable for TIG?
(Allow that polarity, and DC/AC choice is already available). Is a dedicated TIG welder, in addition to MIG, the only sensible option?

Q4. What exactly are the problems of TIG-LIFT. Can we have advice from some who have tried it? Can one get good at it?
 
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I have a lift start TIG machine. Most of the time it isn’t a concern. Situations do arise that would make HF much easier. Some positions are more difficult to get ‘lit up’ and not loose your arc length. It is also another coordination skill you have to develop.


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1) not really. Stick to some degree

2) no

3) you can tig with almost any welder. How well is serious variable.

4) It encourages you to do the thing you should be aiming never to do: contact the work with the tungsten. It's perfectly usable, but at the end of the day, lift or scratch start is either old or cheap technology. The naked truth is that machines lacking HF are made to hit a price point while still claiming "it TIGs". That's not to say that they're not usable, but it's worth setting out exactly why the HF is missing.
 
Lo-Fi said:
1) not really. Stick to some degree

2) no

3) you can tig with almost any welder. How well is serious variable.

4) It encourages you to do the thing you should be aiming never to do: contact the work with the tungsten. It's perfectly usable, but at the end of the day, lift or scratch start is either old or cheap technology. The naked truth is that machines lacking HF are made to hit a price point while still claiming "it TIGs". That's not to say that they're not usable, but it's worth setting out exactly why the HF is missing.
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I have been digging. It would seem that an add-on is possible, and is done. There are YT projects on it, often along with construction of a foot switch.
The types vary a bit also. The few milliseconds of approximately 3kV of 100kHz pulse will set it off, and there are various circuits that do it.

I am getting that one cannot just add a thing like this without some caution about not hurting the welder inverter circuitry, but the RF arc is high impedance, low energy stuff. To be sure I still know very little about it, but the bones of this trick are not yet exposed.

In the case of a simple transformer welder, there is no issue. It is those using inverters that need the care.

I agree entirely that one should seek not to contact the work with the tungsten. With HF start, it would seem that TIG is what the welder inverter does, not matter what. I was trying to tease out whether there is a fundamental difference between the power delivery aspect of TIG welders, compared to others. So far, other than the RF (HF) arc initiation, it would seem not. (OK - we get it that you need a direct cable and the MIG spool motor switched off, and pure Argon instead of 5%, 10%, 15% CO2+Ar).

[Edit]
Another thing that has become clear is that machines that offer LIFT-TIG are using a circuit that detects when the tungsten and the work are in conteact. The energy delivery is not enough to heat either the tungsten point, nor the work. As the point is lifted, it makes a tiny spark, and then the main arc gets going.
 
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The non dedicated machines, it's worth mentioning, are often lacking features such as ramp up/down, proportional pedal control and suchlike. They're not vital and don't stop you welding, but you're kinda missing the point of TIG, or at least some of it. This equally applies to any welding power supply user for TIG that isn't designed for it. It's why I don't bother with TIG on my multi. While it actually has HF, it's DC only and either on or off. That's it.

I've no doubt someone has hacked together an HF add-on, but you're getting into the realms of asking whether something should be done just because you can... As a beginner, the last thing you want is to be fusting around wondering if the mod you made is working properly, or even negatively affecting machine or weld performance when you don't already know one way from the other. In my humble opinion, of course. I'd either use the TIG function as it is, or if you're dead keen buy the proper tool for the job, as it were.

I suspect you've fallen into the trap of over thinking/reading before getting your hands dirty ;)
 
Lo-Fi said:
I suspect you've fallen into the trap of over thinking/reading before getting your hands dirty ;)
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If that be so, then I have the characteristic through my entire life so far as my first memories, of first thinking about what I am about to do.
I have never thought it unusual to read up/learn first. Doing that has sometimes informed me enough to abandon a prospective action altogether.
I do not recognize the concept of "over" thinking anything.
I am also one of those who absolutely does RTFM first, all the way through, every time, no exceptions.
Sorry about that, I just can't shake it! :)
 
Lo-Fi said:
) It encourages you to do the thing you should be aiming never to do: contact the work with the tungsten. It's perfectly usable, but at the end of the day, lift or scratch start is either old or cheap technology. The naked truth is that machines lacking HF are made to hit a price point while still claiming "it TIGs". That's not to say that they're not usable, but it's worth setting out exactly why the HF is missing.
Click to expand...

Lift arc is not old technology. In fact it is rather new technology. Scratch start is old. People get them confused. They are not the same. Lift arc has a really low contact current. When the machine detects the lift of the tungsten off the work, the arc is established and the current then increases to the level needed to weld, either by foot control or a preset amp setting on your machine.

Scratch start is full current.

D
 
[Edit]
Another thing that has become clear is that machines that offer LIFT-TIG are using a circuit that detects when the tungsten and the work are in conteact. The energy delivery is not enough to heat either the tungsten point, nor the work. As the point is lifted, it makes a tiny spark, and then the main arc gets going.
[/QUOTE]

Exactly.

For most work it is perfectly suitable. No good for Aluminium. Really light and small parts can be problematic as they move around on the bench when you "touch" them.
 
i have a Lincoln HF unit on my Miller 250.
i generally use the machine for TIG, but i also use it when welding SMAW, the starts are great
 
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