Arcpig - welding arc starter and stabilizer

[PiotrMisiuna]

I'm a handyman, cheap one unfortunately. I can't afford all the tools I want, so I search for alternatives. This thing really stuck in my head for couple of months. It seams to be able to turn my crappy stick welder into AC aluminum welding capable machine. For a quarter of a price of a full blood TIG. 

http://arcpig.com/
Check out their website, it's fun to read, and watch video. They show scope shot of HF high voltage injection into the sinusoidal welding voltage.

Price is about 350$, plus delivery, from US, to Cyprus it is going to get at least 440 if not more. For me this is still too much.
It seams to be well deign and unfortunately well potted.

I couldn't find any alternatives in EU or chinesium.

Do you know any similar product?
How difficult would it be to MacGyver it out from let's say using crt flyback, in a safe manner?

[tautech]

How difficult would it be to MacGyver it out from let's say using crt flyback, in a safe manner?

It's possible, I made one from coupling from the spark gap from a furnace ignitor years ago. But it's not something you want to take lightly, they're 10 KV and needs careful thought for it be safe.

Simply, the approach is to couple very low power HV into the welding leads with some transformer approach.
Mostly these have been frowned upon these days due to the massive RFI they create but all the large welder manufacturers used the spark gap coupling approach in decades gone by.

You can find examples online but be warned of the voltages and dangers of building something yourself.

[PiotrMisiuna]

The difference - it seams to me - is that furnace igniter has it's own duty cycle.
This what they show in the video triggers hv-hf pulses at the top of the sine wave of the welding transformer output. 
This is probably what makes it a bit safer, since hv is on maybe 5-10% of the time.

[tautech]

The difference - it seams to me - is that furnace igniter has it's own duty cycle.
This what they show in the video triggers hv-hf pulses at the top of the sine wave of the welding transformer output. 
This is probably what makes it a bit safer, since hv is on maybe 5-10% of the time.

Old welders had the HF start HV running continuously but yes modern HF start drops away when the welding arc gets established.
It would not be hard to add a HF start button to the handpiece to turn the HF ON for a short period and then either toggle it OFF or time it out.
I never had 1000:1 scope probes to see what was actually imparted onto the welding voltages, instead just fiddled with values that worked........to a point.
Luckily I now have neighbours and buddys with good HF Tig gear should it be needed. 

Edit
I built one similar to this.
http://www3.telus.net/public/a5a26316/WelderPDFs_Pics/dbARC_START.pdf

[Someone]

I couldn't find any alternatives in EU or chinesium.

Thats because there is a flood of cheap inverter welders available (IGBT or MOSFET), right down to the several hundred dollar price point with HF pilot/start. No need to package and promote an accessory when the whole integrated unit is already available so cheaply.

[Arjan Emm]

Hi Tautech, could you give some information on the coupling transformer you used? That seems the most critical part in that schematic. The hf high voltage could be made in many ways. The transformer ideally has a 1:1 turn ratio, i guess and needs to carry the full welding current without core saturation. So you like as little as possible secondary turns because you need fat wire for it, as short as possible. On the primary hv side you need more turns or high frequency. Getting even more complicated if you use dc welding current.

[tautech]

Hi Tautech, could you give some information on the coupling transformer you used? That seems the most critical part in that schematic. The hf high voltage could be made in many ways. The transformer ideally has a 1:1 turn ratio, i guess and needs to carry the full welding current without core saturation. So you like as little as possible secondary turns because you need fat wire for it, as short as possible. On the primary hv side you need more turns or high frequency. Getting even more complicated if you use dc welding current.

1:1, ~6 turns and the secondary (welding lead) was from some 1/4" solid copper rod I had on hand. (ex powerco 11 KV to xformer droppers.  ) (don't go climbing poles and helping yourself to any    )
Air cored but close coupled with some PVC pipe as a separator.

At the time I had 250 DC or 300AC amps but for Tig I wasn't intending to use more than 150 A so the 1/4" copper was deemed sufficiently heavy.
As mentioned before furnace ignitor transformer, leads and electrodes were used as these were designed to operate continuously albeit not quietly.

It was never a resounding success, it worked to some degree but probably needed more turns on the primary for better start HV arc.

[Arjan Emm]

Thanks, Air core makes sense. but just 6 turns on an aircoretransformer should be horribly inefficient. In hindside, could it be that capacitive coupling was inducing more voltage as the inductive coupling?

[T3sl4co1l]

Old fashioned spark discharge starters run incredibly high peak current at a low duty cycle.  Efficiency isn't a big problem.  It's enough to keep the spark gap ionized, not to deliver real welding heat.

It's also not very reasonable to make, say, a double-tuned air core transformer (that, on account of its tuning, would achieve good efficiency: but the tuning is constantly changing with cable position and arc gap ionization), nor a well coupled, cored type (which would be absolutely monstrous to avoid saturation*).

*On the upside, it only needs to be unsaturated while the arc is weak, or completely absent: a few amperes, or nothing at all.  If the current is high (10s of amperes?), the arc must be conducting, and HF start isn't much needed!


Regarding welding technology: I have all the stuff to design and build hardware here, but what's the point?  I can't make anything under about a buck per watt.  Maybe a third of that once it's into mass production in China, that's it.  Or to put it another way: if you have a few dozen kilobucks floating around for a new product, and you have the connections for cheap production, I can be of help.

Tim

[Circlotron]

Seeing we are trying to establish an ionised path, what if instead of a HF arc we simply directed a small gas flame into the gap between the electrode and the work? This would also preheat the stick and help to get things moving.

[Unixon]

Does anybody have a local copy of this file (http://www3.telus.net/public/a5a26316/WelderPDFs_Pics/dbARC_START.pdf) ?

[BradC]

Does anybody have a local copy of this file (http://www3.telus.net/public/a5a26316/WelderPDFs_Pics/dbARC_START.pdf) ?

Wayback machine to the rescue : https://web.archive.org/web/20201202030107/http://www3.telus.net/public/a5a26316/WelderPDFs_Pics/dbARC_START.pdf

[Andy Watson]

Local ?

Here's mirror http://imajeenyus.com/electronics/20110425_tig_welder_mirror/dbARC_START.pdf If that's not local-enough, put the file name "dbARC_START.pdf" into your favorite search engine.

[Unixon]

Wayback machine to the rescue

Thanks, I completely forgot about this thing.