New AC TIG, sometimes struggling to start?

[FASTdan]

I've purchased a new R-Tech 250 AC TIG to replace my old ebay special machine and so far am very impressed. I thought the old machine was fine but I now realise what a world apart they are.

Anyway, the only issue I have is starting - sometimes I literally cant get it to start. It just sits there fizzing away regardless of torch angle or foot pedal position.

What factors affect the ability to start? I suspect its something I am doing rather than the machine, but not sure what I can improve? Machine settings, Tungsten grinding?

Typically I'm welding AC with a 2.4 tungsten, either 3mm tube butt welds, or 3mm tube to 10mm plate fillets. Max amps set to around 170.

Sometimes I'm finding I pretty much having to scratch to start, but I'm not doing anything different to what I did with the old kit.

 

[matt1978]

Maybe there is a problem with the HF generator on the machine?

Is the problem the same on DC?

 

[Wallace]

Try touching the tungsten on and off the work or earth clamp before pressing the pedal, my TecArc 206i does just the same as you describe and will always strike up once I do this. I keep meaning to ask Weldequip Steve or TecArc themselves as it has been like it since new but I am so used to it now I keep forgetting!

 

[justmental]

i have the TecArc 206i as well Wallace mine is exactly them same the last time it did it i had a good look at the tungsten and see aluminium on the tip.
i used to use a old trans tig this was the same also so like you have just put up with it and carried on. lol

 

[inchpincher]

I get this too (different machine), it's fine when the tungsten is sharp but after a few stop/starts it gets harder and harder for the arc to start. I seem to recall reading about spark gaps on the HF gizmo inside the machine but have never delved deeper, not enough hours in the day!

 

[Wallace]

i have the TecArc 206i as well Wallace mine is exactly them same the last time it did it i had a good look at the tungsten and see aluminium on the tip.
i used to use a old trans tig this was the same also so like you have just put up with it and carried on. lol

I get this too (different machine), it's fine when the tungsten is sharp but after a few stop/starts it gets harder and harder for the arc to start. I seem to recall reading about spark gaps on the HF gizmo inside the machine but have never delved deeper, not enough hours in the day!

I don't remember experiencing the problem on AC but I certainly have on DC, there is a very tiny spark when earthing the tungsten and the arc then starts immediately when the pedal is pressed. I had not noticed any difference in starting between a sharp or worn tungsten as I am so used to earthing out before striking up! I thought the HF start was electronic on the 206i?

 

[hotrodder]

Spark gap set up/servicing is typically more applicable to big 'ol transfomer machines. With inverters the HF is typically adjusted 'digitally'. A bit more detail here... http://www.millerwelds.com/resources/articles/Tips-to-Improve-TIG-Arc-Starts/ along with other tips- many of which are overkill for most applications (remember the articles about low amperage welding, specifically aerospace!)

I'd just phone R-tech and quizz 'em about it. Had a quick scan of the manual and while it mentions HF points there doesn't appear to be any user adjustability to the HF start. With my Lincoln i can vary the HF intensity and with it set to min it can struggle to start a well used blunt tungsten occasionally. Turning it up fixes that but go too far and with a 'super sharp' tungsten used for low amperage DCEN the tip will need a touch up after relatively few starts. Could be their idea of a compromise means the HF is a bit weak for starting a used blunt 2.4mm tungsten, could be something wrong with it.

 

[Paul G]

Spark gap set up/servicing is typically more applicable to big 'ol transfomer machines. With inverters the HF is typically adjusted 'digitally'. A bit more detail here... http://www.millerwelds.com/resources/articles/Tips-to-Improve-TIG-Arc-Starts/ along with other tips- many of which are overkill for most applications (remember the articles about low amperage welding, specifically aerospace!)

I agree with Hotrodder about the old sets. They had HF that would jump the English Chanel.
Not so with modern inverters.

I'm no expert on electrics but it seems to me like static build up, and touching the tungsten on the work/bench
prior to pressing the trigger/foot pedal does release it.

The Miller site does suggest earthing absolutly everything within the welding zone but this does seem a bit OTT.
I did however run a wire from an earth stake to my bench and this did improve HF starting.
I only now have problems if the tungsten is dirty.

Cheers,
Paul G

 

[FASTdan]

Thanks for the replies - seems I am not alone. I will try touching the workpiece prior to start and see if that has a bearing on it. I should also probably call R-Tech as suggested.

It is definitely only apparent when the tungsten has balled up - on a newly sharpened tip it strikes up instantly.

The Miller site does suggest earthing absolutly everything within the welding zone but this does seem a bit OTT.
I did however run a wire from an earth stake to my bench and this did improve HF starting.
I only now have problems if the tungsten is dirty.

Cheers,
Paul G

Daft question - but what exactly is required as an earth stake? will a decent size rawl bolt into the concrete floor suffice? Might be worth me earthing the bench properly.

 

[Paul G]

Usually a long copper plated steel rod that you hammer down into the damp subsoil.

I happened to have a metre of 12mm stainless round bar to hand and welded a lug on the end for the wire.
I drilled a hole in the corner of the concrete workshop floor and knocked it in.

Cheers,
Paul G

ps. Watch out for your sewer and water main.

 

[J_K]

I "sometimes" have exactly the same problem with my super high quality chinese machine.
Sometimes it just won't get the HF arc. Touch the work piece with the tungsten and you're away. I just put it down to the quality of the kit I'd bought but it seems like it might be a more widespread poblem.

 

[matt1978]

Its usually partly due to the weakness of the HF generated from the cheaper machines. But its also a build up of static in the system, touching the tungsten to ground dis-charges the circuit.

Some machines have features to minimise this, bigger/stronger HF generator, RPi (Pre-Heated Tungsten) etc